Relative gravity is a measure that helps to assess the functioning of the kidneys by the content of urine. The amount of fluid moving through the body is unstable. Its volume indicators vary depending on various circumstances:
- daily time;
- intake of salty and spiced food;
- the amount of water in the diet;
- perspiration during sports.
Primary urine is formed after blood is filtered by capillary cells. For a day, from 150 liters of primary urine, approximately 2 liters of secondary are formed.
The main reason for the decrease in the level of urine density is the failure of the production of vasopressin, a peptide hormone of the hypothalamus.
For example, in certain forms of diabetes insipidus, the amount of urine excreted by the patient per day can be up to 20 liters at the prescribed rate of 1.5 liters. This is due to the actual lack of vasopressin in humans.
Antidiuretic hormone (ADH) is stored in the pituitary gland and then released into the bloodstream. Its main functions:
- fluid retention in the human body;
- arterial stenosis.
ADH improves fluid reabsorption, regulates the concentration of urine, lowers its amount. By normalizing the abundance of water in the body, vasopressin increases the permeability of fluid in the kidney channels.
The accumulation of solids in urine is a variable value, directly dependent on the composition of the blood plasma. Humoral and nervous biomechanisms are responsible for this process.
The fact that a person has a reduced specific gravity of urine is often found when determining pathologies that are in no way related to the urinary organs. The determination of relative density is done after examination of the general analysis of urine, along with the number of leukocytes, as well as products of protein metabolism.
The low specific gravity of the liquid is found out during the implementation of special tests:
- research on Nechiporenko;
- Folgard's diagnosis.
Carrying out these measurements helps to obtain the most accurate results of relative density and even approximately establish the cause of hypostenuria.
The main instrument with which samples are taken is the urometer, which determines the density.
The analysis includes several steps:
- The biological fluid is placed in a cylindrical vessel. When a little foam has formed, it is removed with filter paper.
- The urometer is lowered into the urine so that the device does not touch the walls of the container.
- After the urometer stops fluctuating, the specific gravity is read along the border of the lower meniscus.
To get the most truthful result, it is necessary to take into account the air temperature, taking an average of 15 ° C as a basis.
The reasons
The specific gravity of the released liquid is considered to be reduced when the level is up to 1.01. This state of affairs indicates a decrease in the efficient activity of the kidneys. The ability to filter harmful elements is significantly reduced, which can cause slagging of the body, the appearance of various complications.
However, this indicator is sometimes considered the norm. For example, during pregnancy in women, hypostenuria often develops with the manifestation of toxicosis. In this state, sometimes there are disturbances in the functioning of the gastrointestinal tract, causing water retention in the body. Expectant mothers suffer from urinary disorders - urine is emitted often, but in small quantities.
Violation of the specific gravity of urine in women expecting the birth of a baby also happens for the following reasons:
- Changes in the hormonal field. The increased level of female hormones causes a certain imbalance of other biological substances.
- While carrying a child, many factors appear in the body that affect the decrease in the active functioning of the kidney. This is an enlarged uterus that compresses the pelvic organs. Also, there is an expansion of blood vessels, which increases the load on the kidneys.
After the birth of the baby, urine is taken from him to determine the work of the kidneys and assess the overall state of health. The density of the liquid discharge, as a rule, in a baby is not more than 1.015-1.017. These data remain for the first month, and then begin to increase after changing the order of nutrition.
Pathological conditions in which there is a decrease in the specific gravity of urine:
- nephrogenic diabetes insipidus;
- polydipsia (intense thirst);
- neurogenic diabetes insipidus.
These are diseases in which the production of vasopressin decreases and fluid is not reabsorbed. With any urination, a considerable amount of urine is released with a small content of urea and its salts.
The relative density of urine is an important diagnostic indicator, according to which the pathological conditions of the patient are determined. Depending on the disease and the stage of its course, urine can have completely different relative density, including low.
The relative density of urine is below normal - what can it indicate?
Such a study is carried out to determine the current work of the kidneys. These can include samples of Zimnitsky and Nechiporenko. The latter belong to the category of the most detailed laboratory studies, the results of which take into account the concentration of urea and salts. If these substances are contained in an amount that differs from the norm downwards, then the patient has a clearly reduced urine density - hypostenuria.
Since the specific gravity of urine is an integral part of the functional indicators of the functioning of the kidneys, it can be directed to its diagnosis if you suspect:
- Pathology of the kidneys.
- Inflammatory processes in other structures of the genitourinary system.
- somatic disorders.
Norm of density values in accordance with the mechanisms of urine formation
There are several stages of urine formation, after which the material necessary for analysis is formed.
At the first stage in the renal glomeruli, the formation of urine of the primary composition occurs. In this case, the blood under the influence of internal renal pressure undergoes purification from toxins and other elements formed as a result of the past cycle.
In the second stage, the products separated from the blood go through the stages reabsorption through jade channels. Any useful substances that could be separated under the influence of pressure are re-returned to the body. The output is urine, which contains extremely harmful substances, such as chlorine, sodium, various sulfates, and so on.
It is this material obtained that is used for analysis by means of a urometer.
Based on the results obtained, namely the fixation of the content of salts and urea, the value is determined. The latter cannot be called constant, since during the day, in the same biological material, the density can change several times. It depends on food, drinks, as well as banal fat loss through sweating.
Indicators within the normal range according to the principle of age division
- baby 1 day old 1,008-1,018 (density according to the urometer);
- 6 months - 1,002-1,004 .
- from six months to 12 months - 1,006-1,016 .
- age from 1 to 5 years - 1,010-1,020 .
- from 6 to 8 years old - 1,012-1,020 .
- from 9 to 12 - 1,012-1,025 .
- adult men and women 1,010-1,025 .
It is worth noting that upon reaching the age of twelve, the density index of the analyzed urine is completely comparable with the index for the biological material of an adult.
Causes of a decrease in the density of urine
The study can show the presence of hypostenuria only if the density decreases to 1,005-1,010 . In this case, such indicators indicate a decrease in renal function, an integral part of which are antiarrhythmic hormones. With an increase in the number of the latter, the most rapid absorption of water in the body is provoked, as a result of which there is a decrease in the concentration of urine.
Thus, the action fully works in the opposite direction, that is, in the absence or decrease in the amount of the mentioned hormones, the urine is concentrated too much, due to the increase in the amount of water. Under the condition of such a sharp increase in the amount of the analyzed liquid, its specific gravity decreases accordingly.
This is one of the most common reasons for the decrease in the mentioned indicator, but, in fact, there are much more of them.
Decreased density of urine in pregnant women
It should be noted right away that the normal indicator for a pregnant woman is 1.010-1.020. The causes of hypostenuria during pregnancy may be:
- Any renal pathology.
- Failure of the hormonal background.
- Too frequent urination.
- Usual toxicosis.
Density of urine in newborns and children
At the time of birth, the indicator may drastically deviate from the established norm. After some time, this figure returns to normal. If a one-year-old child is diagnosed with hypostenuria, then until the age of two, there is absolutely no need to worry.
Otherwise, you should contact a specialist and undergo an examination.
Decreased urine density in adults
In the adult part of the population, there are much more pathological reasons for the formation and course of a decrease in urine density. These include:
- Kidney failure, which has developed into a chronic disease.
- central diabetes.
- Pyelonephritis.
- Nephritis in a chronic form.
- A consequence of any inflammatory processes in the body upon the resorption of inflamed areas.
- Nephrosclerosis.
- Jade in an intense form.
- Dystrophy caused by starvation.
- Glomerulonephritis.
- Exposure to antibiotics or diuretics.
It is worth paying attention to the fact that a decrease in the specific gravity of urine can be caused by alcoholism or drug use.
What to do with the diagnostic results?
If the decrease in the specific gravity of urine is caused by a natural factor, such as the consumption of a certain type of food and liquid, then you should not worry, but, on the contrary, exclude certain types of foods from the diet.
If the cause was one of the previously mentioned diseases, then you should immediately contact a specialist for advice and additional examinations. Through the latter, special drugs are prescribed, during which a decrease in urine density can also be diagnosed.
Determines the state of the urinary system, reveals violations in the work of other internal organs. The key indicator is the specific gravity of urine or its relative density.
Deviation from the norm up or down indicates a violation of the functional abilities of the organ. According to the results of the study, doctors judge how well the kidneys filter and remove urine.
Regardless of the amount of fluid drunk, all metabolic products are excreted by the kidneys. If the body has received an insufficient amount of water, the specific gravity of urine increases, urine is oversaturated with minerals. The doctor diagnoses hyperstenuria. If a person drinks an excessive amount of liquid, hypostenuria is observed. The liquid contains a small amount of dry residue, the density decreases.
If the fluid concentration is normal, the kidneys work without failure. It is easy to determine why the relative density of urine changes if you know the process of fluid formation.
The process of making urine
Glomerular capillaries are involved in the formation of fluid, blood is filtered through them. Large cells should not penetrate into the glomeruli of the capsule:
- fats;
- proteins;
- glycogens.
This fluid is similar in composition to blood plasma.
The fluid follows the tubule of the nephron and enters the renal tubules. At this stage, nutrients are absorbed back into the blood. Secondary urine remains, it contains the decay products of proteins, fats and carbohydrates. It is excreted from the body during urination.
The dry residue consists of the following components:
- urea;
- chlorides;
- sulfates;
- ammonia ions;
Substances are harmful to the body and must be eliminated.
Specific gravity of urine
If the specific gravity of urine is normal, this indicates that the kidneys are successfully coping with the dilution function. This indicator is influenced by the ambient air temperature, individual characteristics and needs of the body.
Depending on these factors, the amount of metabolic products in the secondary urine changes. The indicator changes during the day a large number of times: after each meal and liquid.
The indicator is affected by increased sweating in hot weather, after playing sports or during illness. The fluid is released in the form of sweat, with each exhalation.
The relative density of urine normally ranges from 1.015 to 1.025. Morning fluid stays at 1.02, what does that mean? The increased relative density of urine in the morning increases due to the lack of fluid intake, its retention in the body (lack of urination, slow sweating and breathing).
Toward evening, the weight of the dry residue decreases. The analysis is given in the morning on an empty stomach, since morning urine best characterizes the functionality of the kidneys, regardless of external factors.
In children, the rate is different. In an infant, the value should not be less than 1.010. The indicator is compared with an adult over 12 years of age.
How is the analysis carried out?
To determine the specific gravity of urine, a special device is used - a urometer. The laboratory assistant takes a certain amount of material and pours it into the cylinder along the walls so that it does not foam. The device is placed in a special liquid, the diameter of the urometer is larger than the diameter of the cylinder. Density is determined by the scale of the device.
If the patient cannot independently pass the material for the analysis of the specific gravity of urine, this happens with some diseases, the sampling is performed by a catheter. For the study, a few drops of liquid are needed. It is easy to dilute it in distilled water and calculate the specific gravity using the modified formula.
This is how the Urometer looks like to determine the specific gravity of urine
If it was not possible to take the required amount of urine, then it is examined as follows:
- a drop of liquid is added to a mixture of chloroform and benzene and placed in a cylinder;
- if a drop floats to the surface, the relative density is lowered, and if it falls to the bottom, it is increased.
To bring a drop of urine to the center of the cylinder, the proportions of substances are changed. The specific gravity of urine will be equal to the specific gravity of the solution.
Increased specific gravity of urine
When pathological processes appear in the body, the density of the liquid changes. Causes of hyperstenuria:
- endocrine disorder;
- kidney failure;
- glomerulonephritis.
Any of the above factors leads to a problem, the disease entails a decrease in the amount of fluid in the body.
Regardless of gender, the specific gravity of urine is increased for the following reasons:
- diseases of the urinary system;
- taking certain medications (antibiotics);
- period of pregnancy;
- mechanical damage to the abdominal organs;
- intestinal obstruction;
- with diseases that provoke a large loss of fluid.
If hyperstenuria was determined in a child, this is due to malnutrition, birth defects, acquired diseases. Often, infants suffer from infectious diseases due to a weak, not yet formed immune system. Diarrhea and vomiting increase the amount of dry residue.
It is also necessary to determine the functionality of the kidneys in diabetes mellitus. During the disease, the amount of protein in urine, the weight of the dry residue increases.
In addition to quantitative, the laboratory assistant also analyzes the qualitative indicators of the liquid. When making a diagnosis, the doctor evaluates the complaints of patients. Low density is manifested by the following symptoms:
- deterioration of the general condition of the body, drowsiness;
- abdominal pain;
- bad smell;
- dark color of urine;
- a small amount of liquid released;
- swelling.
Increased urine density appears for physiological and pathological reasons. In the first case, we are talking about insufficient intake of water in the body. The situation does not require medical treatment, it is easy to lower the rate by changing the diet.
In the second case, a high specific gravity is the cause of diseases of the endocrine or urinary system; in order to avoid complications, it requires therapeutic treatment.
Decreased specific gravity of urine
A low specific gravity of urine manifests itself after past illnesses. Plentiful drinking is recommended during and after diseases of the gastrointestinal tract. Do not worry if the indicator decreases in hot weather or after taking diuretics, laxatives.
Diseases leading to a decrease in the specific gravity of urine:
- pathology of the organs of the urinary system of acute and chronic nature;
- starvation, lack of nutrients;
- diabetes insipidus in patients suffering from diseases of the nervous system;
- diabetes insipidus during pregnancy;
- diabetes insipidus of nephrogenic origin;
- diabetes insipidus of a neurogenic nature, leading to dehydration;
- interstitial type nephritis;
- tubular lesions;
- involuntary polydipsia;
- alcohol abuse.
During diabetes insipidus, the body is able to excrete 10 times more urine, so the specific gravity is below normal. A decrease in the indicator occurs with improper functioning of the hypothalamus, a violation of the release of the peptide hormone, as well as vasopressin. The latter is responsible for maintaining fluid in the body.
If the patient has a large amount of hormones, this leads to increased absorption of water in the body, the urine concentration will decrease.
If the specific gravity of urine is low, the kidneys cannot filter out harmful substances, which leads to slagging and poisoning of the body.
The relative density of urine is an indicator that carries the maximum information about the state of the human urinary system. Doctors determine the condition of the kidneys and bladder in several ways. Low specific gravity of urine, the patient needs to review the diet, undergo additional tests.
Urinalysis for specific gravity should be carried out twice a year: in winter and summer, when the body is susceptible to viruses and bacteria.
The patient is obliged to undergo preventive examinations every year, the condition of the internal organs must be monitored. The health of the bladder, kidneys and tubules requires attention from the patient and the attending physician.
The patient is obliged to introduce a rule into his life: drink clean water in the amount of 2 liters per day. The uniform use of water at room temperature will bring the kidneys back to normal. The amount of caffeine should be reduced by drinking 1 cup of coffee every 3 days.
Today, not a single examination of a patient is complete without passing laboratory tests, which include a general urine test. Despite its simplicity, it is very indicative not only for diseases of the genitourinary system, but also for other somatic disorders. The specific gravity of urine is considered one of the main functional indicators of the kidneys and allows you to evaluate their filtration function.
Urine formation
Urine in the human body is formed in two stages. The first of these, the formation of primary urine, occurs in the renal glomerulus, where blood passes through numerous capillaries. Since this is carried out under high pressure, filtration occurs, separating blood cells and complex proteins that are retained by the capillary walls, from water and amino acid molecules, sugars, fats and other waste products dissolved in it. Further, following the tubules of the nephron, the primary urine (from 150 to 180 liters can be formed per day) undergoes reabsorption, that is, under the action of osmotic pressure, the water is again absorbed by the walls of the tubules, and the beneficial substances in it enter the body again due to diffusion. The remaining water with urea, ammonia, potassium, sodium, uric acid, chlorine and sulfates dissolved in it is secondary urine. It is she who enters the bladder through the collecting ducts, the system of small and large renal calyces, the renal pelvis and ureter, where it accumulates and then is excreted into the environment.
How is specific gravity determined?
To determine the density of urine in the laboratory, a special device is used - a urometer (hydrometer). For the examination, urine is poured into a wide cylinder, the resulting foam is removed with filter paper and the device is immersed in the liquid, trying not to touch the walls. After stopping the immersion of the urometer, it is slightly pressed from above and, when it stops oscillating, the position of the lower urine meniscus is noted on the scale of the device. This value will correspond to the specific gravity. When measuring, the laboratory assistant must also take into account the temperature in the office. The fact is that most urometers are calibrated to operate at a temperature of 15 °. This is due to the fact that when the temperature rises, the volume of urine increases, respectively, its concentration decreases. When decreasing, the process goes in the opposite direction. In order to remove this error? for every 3° above 15°, 0.001 is added to the value obtained, and, accordingly, for every 3° below, the same value is subtracted.
Normal specific gravity
The relative density indicator (this is another name for the specific gravity) characterizes the ability of the kidney, depending on the needs of the body, to dilute or concentrate the primary urine. Its value depends on the concentration of urea and salts dissolved in it. This value is not constant, and during the day its indicator can change significantly under the influence of food, drinking regimen, the processes of excretion of fluid with sweat and respiration. For adults, the specific gravity of urine will normally be 1.015-1.025. The density of urine in children is somewhat different from that of adults. The lowest numbers are recorded in newborns in the first days of life. For them, the specific gravity of urine can normally vary from 1.002 to 1.020. As the child grows, these figures begin to rise. So, for a five-year-old child, indicators from 1.012 to 1.020 are considered the norm, and the specific gravity of urine in children of 12 years old is almost the same as in adults. It is 1.011-1.025.
If the specific gravity of urine is low
Hypostenuria, or a decrease in specific gravity to 1.005-1.010, may indicate a decrease in the concentration ability of the kidneys. It is regulated by antidiuretic hormone, in the presence of which the process of water absorption is more active, and accordingly, a smaller amount of more concentrated urine is formed. And vice versa - in the absence of this hormone or its small amount, urine is formed in large volumes, which have a lower density. The reason that the specific gravity of urine is lowered may be the following conditions:
diabetes insipidus;
acute pathology of the renal tubules;
chronic renal failure;
polyuria (a large amount of urine excreted), which occurred as a result of heavy drinking, when taking diuretics, or when resolving large exudates.
Why is the specific gravity decreasing?
It is customary to single out three main reasons leading to a pathological decrease in the specific gravity.
Polydipsia - excessive water intake, which leads to a decrease in the concentration of salts in the blood plasma. In order to compensate for this process, the body increases the production and excretion of urine in large volumes, but with a reduced salt content. There is such a pathology as involuntary polydipsia, in which there is a low specific gravity of urine in women with an unstable psyche.
Causes with extrarenal localization. These include neurogenic diabetes insipidus. In this case, the body loses the ability to produce antidiuretic hormone in the required quantities and, as a result, the kidneys lose the ability to concentrate urine and retain water. The specific gravity of urine may decrease to 1.005. The danger is that even with a decrease in water intake, the amount of urine does not decrease, which leads to dehydration. Damage to the hypothalamic-pituitary region due to trauma, infection, or surgery can be attributed to the same group of causes.
Causes associated with kidney damage. Low specific gravity of urine often accompanies diseases such as pyelonephritis, glomerulonephritis. Other nephropathies with parenchymal lesions can be attributed to the same group of pathologies.
Hyperstenuria, or an increase in the specific gravity of urine, is usually seen with oliguria (decreased urine output). It can occur due to insufficient fluid intake or with large losses (vomiting, diarrhea), with an increase in edema. Also, an increased specific gravity can be observed in the following cases:
in patients with glomerulonephritis or cardiovascular insufficiency;
with intravenous administration of mannitol, radiopaque substances;
when removing certain drugs;
increased specific gravity of urine in women may be with toxicosis of pregnant women;
on the background of proteinuria in nephrotic syndrome.
Separately, it is necessary to mention the increase in the density of urine in diabetes mellitus. In this case, it may exceed 1.030 against the background of an increased volume of urine (polyuria).
Functional trials
To determine the functional state of the kidneys, it is not enough just to do a urine test. The specific gravity can change during the day, and in order to accurately determine how much the kidneys are able to excrete or concentrate substances, functional tests are carried out. Some of them are aimed at determining the state of the concentration function, others - excretory. It often happens that violations affect both of these processes.
Breeding test
The test is carried out subject to patient bed rest. After an overnight fast, the patient empties the bladder and drinks water at the rate of 20 milliliters per kilogram of his weight for 30 minutes. After all the liquid has been drunk and then at intervals of one hour 4 times, urine is collected. After each urination, the patient additionally drinks the same volume of liquid that was allocated. The selected samples are evaluated for quantity and specific gravity.
If in healthy people the specific gravity of urine (norm) in women and men should not decrease below 1.015, then against the background of water load, the density can be 1.001-1.003, and after its cancellation it increases from 1.008 to 1.030. In addition, during the first two hours of the test, more than 50% of the liquid should stand out, and at its completion (after 4 hours) - more than 80%.
If the density exceeds 1.004, then we can talk about a violation of the dilution function.
concentration test
To conduct this examination, drink and liquid food are excluded from the patient's diet for a day and include food with a high protein content. If the patient suffers from severe thirst, it is allowed to drink in small portions, but not more than 400 ml per day. Every four hours, urine is collected, assessing its quantity and specific gravity. Normally, after 18 hours without fluid intake, the relative density should be 1.028-1.030. If the concentration does not exceed 1.017, then we can talk about a decrease in the concentration function of the kidneys. If the indicators are 1.010-1.012, then isosthenuria is diagnosed, that is, the complete loss of the kidney's ability to concentrate urine.
Zimnitsky's test
The Zimnitsky test allows you to simultaneously evaluate both the ability of the kidneys to concentrate and the ability to excrete urine and do this against the background of the usual drinking regimen. For its implementation, urine is collected in portions every 3 hours during the day. In total, 8 servings of urine are obtained per day, in each of which the amount and specific gravity are fixed. Based on the results, the ratio of night and day diuresis is determined (normally it should be 1:3) and the total amount of excreted fluid, which, along with monitoring the specific gravity in each portion, allows us to evaluate the work of the kidneys.
The specific gravity of urine (the norm for women and men is given above) is an important indicator of the ability of the kidneys to function normally, and any deviation makes it possible, with a high degree of probability, to identify the problem in time and take the necessary measures.
The specific gravity of urine in normal and pathological conditions
You were given the results of the research in the laboratory. What can a person who understands little about medicine feel when looking at these incomprehensible numbers? First of all, confusion. Of course, it is not very difficult to determine the increase or decrease in this or that indicator, because the normal values \u200b\u200bare indicated in the same form. To interpret the obtained figures, certain knowledge is required. Take the well-known urine test. The first thing that attracts attention is the specific gravity of urine. What does this indicator say? 
Urine specific gravity (also called urine relative gravity) measures the ability of the kidneys to concentrate substances in the urine to be removed from the body. These include, in particular, urea, urinary salts, uric acid and creatinine. The specific gravity of urine is normally in the range from 1012 to 1027, it is determined using a urometer. The measurement is carried out in the laboratory. Recently, the determination of the density of urine is carried out on special equipment using dry chemistry methods.
If fluid is excreted from the body more than usual, then the concentration of dissolved substances in the urine decreases. Consequently, the specific gravity of urine also decreases. This condition is called hypostenuria. It can be noted in healthy people who consume large amounts of fluid after taking diuretic foods (watermelons, melons). Fans of various diets may experience a decrease in the indicator (due to a lack of protein foods in the diet, especially during fasting).
With various diseases of the kidneys, their ability to concentrate various substances in the urine is impaired, therefore, the decrease in specific gravity is not due to excessive fluid intake, but to a violation of the kidneys (pyelonephritis or glomerulonephritis, nephrosclerosis). Hypostenuria occurs in patients during the period of resorption of edema or effusions, when the fluid accumulated in the tissues quickly leaves the body. A decrease in the density of urine occurs while taking diuretic drugs. Monotonous specific gravity during the day should alert the doctor to pyelonephritis (especially in combination with nocturnal urination).
An increase in relative density above 1030 is called hyperstenuria. A similar condition occurs in people with insufficient fluid intake. The specific gravity of urine, the norm of which is directly proportional to the drinking regimen of a person, can increase in the hot season, when a person sweats profusely, therefore, loses a lot of moisture. High numbers of this laboratory indicator are typical for workers in hot shops: cooks, blacksmiths, metallurgists.
Hyperstenuria also occurs with thickening of the blood, which occurs due to profuse vomiting or diarrhea. In patients with heart disease, there is an accumulation of fluid in the body, as a result of which diuresis decreases and the specific gravity of urine increases. In patients with diabetes mellitus, high specific gravity numbers are often detected in laboratories. In this case, this indicates a large amount of glucose in the urine.
The indicator also indirectly indicates how the patient adheres to the recommended drinking regimen. This is important for patients with kidney disease and urolithiasis.
A single change in the indicator is not decisive for making a diagnosis, since daily fluctuations in the specific gravity can range from 1004 to 1028, and this is normal.
Urine density. Deciphering the general analysis of urine
A person has to deal with various medical services during his life. This may be a consultation with a medical specialist, a study of any biomaterials, an examination of internal organs, and taking various medications. A general urine test is taken by absolutely all people, it is prescribed to all people - from infants to pensioners. This is the most common and at the same time informative method for examining urine.
Urinalysis: what is this study?
The analysis data is an indicator of kidney function, therefore, at the slightest suspicion of their dysfunction, doctors prescribe this study. In addition, the results of the analysis may indicate other pathological processes in the body. This method can detect abnormal functioning of organs by determining the general properties of urine and microscopy of the urinary sediment. The main parameters by which the doctor draws conclusions about the patient's condition are as follows:
- urine color;
- its transparency;
- urine density;
- the presence of protein;
- acidity;
- glucose indicators;
- what is the patient's hemoglobin;
- bilirubin;
- ketone bodies;
- urobilinogen;
- nitrites;
- the presence of salts in the urine;
- epithelium;
- the number of red blood cells;
- leukocytes;
- what bacteria are in the urine;
- cylinders.
This study for patients with kidney pathologies is prescribed quite often to monitor the dynamics of changes in the excretory system and the effectiveness of the medications used. A healthy person should ideally take this analysis 1-2 times a year for the timely detection of pathologies.
What are the rules for collecting analysis?
The study must be carried out with the utmost precision. It must be provided from the beginning of the urine collection to the final results. Before collecting urine, it is necessary to conduct hygiene of the relevant organs. It is necessary to pay attention to the fact that various food jars or containers are not suitable for analysis. To collect biomaterial, a special container is needed, used only for these purposes. You can buy it at any pharmacy.
In the evening before taking the test, you need to limit the use of foods that can color urine: beets, carrots and others. In addition, you need to monitor the use of various medications the day before, as they can distort the results of the tests. During the period of menstruation, the results may also be untrue, so you need to wait until the end of this period.
You can not drink alcoholic beverages in the evening before the analysis. The content of trace elements in the urine can change significantly.
What can be revealed by this analysis?
A general urine test is prescribed in order to determine the state of the body in case of suspicion of certain pathologies. This analysis is prescribed in the event of diseases of the urinary system, to determine the dynamics of the course of the disease and control it. The analysis helps to prevent possible complications in time, and also shows the effectiveness of the treatment. This study is also often used in examinations of people undergoing medical examinations.
Determination of urine density
The density of urine is the relative density ratio of two materials, one of which is considered as a reference. In this case, the sample is distilled water. The density of urine is usually variable. The reason is that the density changes during the day, this is due to the uneven output of metabolic products dissolved in the urine.
When filtering the blood, the kidneys form primary urine, most of which is reabsorbed and returned to the bloodstream. Based on the described process, the kidneys make a concentrate of secondary urine. The process described above is called the concentration function of the kidneys. If there is a violation of the latter, this will lead to a decrease in the relative density of urine. Diabetes insipidus, some variants of chronic nephritis and other diseases can become a violation of the concentration function.
If protein, sugar, leukocytes, erythrocytes and the like appear in the urine, this contributes to an increase in the density of urine. The relative density of urine, or rather, its average value depends on the age of the person. The concentration function of the kidneys also depends on age. Generally speaking, these two concepts are closely related.
Physiology of urine density
The density of urine, or rather, the process of its occurrence, consists of three stages. These are filtration, reabsorption and tubular secretion.
The first stage - filtration - occurs in the Malpighian body of the nephron. It is possible due to the high hydrostatic pressure in the glomerular capillaries, which is created due to the fact that the diameter of the afferent arteriole is larger than that of the efferent one.
The second stage is called reabsorption or, in other words, absorption in the opposite direction. It is carried out in the twisted and even tubules of the nephron, where, in fact, the primary urine enters.
The final, third stage of urination is tubular secretion. The cells of the renal tubules, together with special enzymes, carry out an active transfer from the blood capillaries into the lumen of the tubules of toxic metabolic products: urea, uric acid, creatine, creatinine and others.
The norm of the relative density of urine
The relative density of urine normally has a wide range. Moreover, the process of its formation will be determined by normally functioning kidneys. The relative density of urine tells a specialist a lot. The rate of this indicator will fluctuate during the day many times. This is due to the fact that from time to time a person takes various foods, drinks water and loses fluid through sweating, breathing and other functions. Under various conditions, the kidneys excrete urine with relative density values: 1.001 - 1.040. It is believed that this density of urine is normal. If a healthy adult drinks enough water, then the relative density of urine, the norm of which is indicated above, in the morning can have the following indicators: 1.015 - 1.020. Morning urine can be very saturated, as no fluid enters the body at night.
The density of urine is normal if its color is straw-yellow, transparent and has a mild odor. Her reaction should range from 4 to 7.
Why is hyperstenuria dangerous?
If a person has an increased density of urine, this indicates that certain pathological processes are occurring in the body, which in a word are called "hyperstenuria". Such a disease will be manifested by an increase in edema, in particular, with acute glomerulonephritis or insufficient blood circulation in the kidneys. If there was a huge extrarenal fluid loss. This includes diarrhea, vomiting, large blood loss, burns over a large area, swelling, abdominal trauma, intestinal obstruction. Hyperstenuria will also be indicated by the appearance in the urine of a large amount of glucose, protein, drugs and their metabolites. The cause of this disease is also toxicosis during pregnancy. If you passed a urine test, the specific gravity of which turned out to be high (more than 1030), this result will indicate hyperstenuria. Such results must be discussed with the doctor.
The high density of urine does not carry a great danger to human life. But it is of two types:
- Kidney disease, such as nephrotic syndrome.
- Absence of primary pathology of the kidneys (glucosuria, multiple myeloma, hypovolemic conditions in which water reabsorption in the tubules increases as compensation, and therefore urine concentration begins).
What does hypostenuria indicate?
Hypostenuria is the opposite of hyperstenuria. It is characterized by low urine density. The cause is acute damage to the renal tubules, diabetes insipidus, permanent renal failure or malignant hypertension.
Hypostenuria indicates that there has been a violation of the concentration ability of the kidneys. And this, in turn, speaks of kidney failure. And if you have been diagnosed with this disease, it is advisable to immediately contact a nephrologist who will prescribe you the timely and necessary treatment.
Urine Density Norms for Children
As mentioned in this article above, urine density norms are different for each age. The urine analysis of an adult differs significantly from that of a child. It can vary in many ways, but its main difference is in the norms. The relative density of urine in a child must meet the following standards:
In a one-day-old baby, the norm is from 1.008 to 1.018;
If the baby is about six months old, for him the norm will be 1.002–1.004;
Between the ages of six months and one year, the normal relative gravity of urine is in the range of 1.006 to 1.010;
Between the ages of three and five, urine density limits will range from 1.010 to 1.020;
For children who are about 7-8 years old, 1.008–1.022 is considered the norm;
And those who are between 10 and 12 years old, their urine density should correspond to the norm of 1.011-1.025.
It can be very difficult for parents to collect urine from their child, especially if he is very small. But in order to determine the density of urine, at least 50 ml must be delivered to the laboratory where such an analysis is carried out.
General urine analysis: transcript
Urinalysis helps to identify many diseases and draw a conclusion about the general state of human health. The interpretation and results are communicated to the patient by the doctor. In this article, we will consider the most significant indicators. 
Amount of urine
The first point from which the decoding of the general analysis of urine begins is its quantity. To determine the necessary indicators, you need only 100-200 ml of liquid. A larger number may affect the determination of the specific gravity. The total amount of urine (diuresis) per day should be 1-2 liters. That's about 7 urinations.
Color
Pigments affect urinalysis. Decoding may indicate a light or saturated yellow color. Actually, this is the norm. A color that is too dark means there is no fluid in the body. Urine may be red in color, indicating the presence of red blood cells in it. Green will indicate bilirubin. The color of the liquid also changes from certain drugs (pyramidone, naphthol, etc.) and food (beets, rhubarb, blueberries).
Smell
The described smell, along with other indicators, is taken into account by the doctor when making a diagnosis. Fresh morning urine should not smell harsh. The smell of fruits is in diabetes mellitus, ammonia - in the case of cystitis, putrefactive - in gangrenous processes. This indicator is also influenced by drugs and food that are used and taken by a person. 
Transparency
Transparency also establishes a urinalysis. Decoding involves the separation of the liquid into transparent (normal), translucent and cloudy (indicates the presence of epithelium, bacteria, erythrocytes, salts, leukocytes).
Reaction (PH)
You can prevent the formation of kidney stones if you pass a urine test on time. The main role in this case is played by RN. The norm should be 6.25-6.61. It is neutral, slightly acidic. An indicator lower than 4, in fact, leads to the appearance of stones.
Specific gravity 
Using this indicator, one can suspect such terrible diseases as heart failure, glomerulonephritis, diabetes mellitus (if the specific gravity exceeds the norm), and pyelonephritis (if the norm is too low). Ideally, the indicator should be between 1012 and 1025. The data may change during the day.
red blood cells
Not everything is normal with human health if the presence of red blood cells showed a general urine test. Decryption should indicate their absence. Among the diseases in which red blood cells appear in the urine, there are tumors, stones in the ureters and kidneys, poisoning, lupus erythematosus, hypertension and others.
Leukocytes
The allowable number of leukocytes for men and women is different. So, for the first, it should be up to 3 in the paragraph, for the latter it is allowed up to 5 in the paragraph. Identification of their excessive amount makes it possible to suspect inflammatory diseases of the urinary system.
At the moment, all examinations of the state of human health are accompanied by the delivery of laboratory tests. The most common and informative is urinalysis, the results of which can be used to judge not only the presence of pathologies of the urinary system, but also other diseases in the body. An important indicator of the analysis is the relative density of urine, which allows to evaluate the functional activity of the kidneys, their ability to accumulate, filter and excrete urine.
The deviation of the specific gravity of urine from the norm helps to identify pathologies at their initial stage and immediately begin drug therapy.
What is laboratory analysis based on?
The specific gravity of urine is an indicator that characterizes the ability of the kidneys to increase or decrease the concentration of urine. Biological fluid is formed in the kidneys in several stages. First, under the pressure of blood in the glomerular capillaries, the components of the blood are filtered through their walls. The composition of primary urine is close to that of blood plasma. But there are differences: the molecules of proteins, fats and glycogen are too large and are not able to penetrate through the vascular walls into the glomeruli of the capsule.
Moving along the tubule of the nephron, primary urine (about 160 liters per day) is reabsorbed into the renal tubules. There is a process of reabsorption of nutrients into the bloodstream. Residual fluid with the breakdown products of proteins, fats and carbohydrates contained in it form secondary urine, which is excreted during urination. This dry residue is represented by:
- urea;
- salts of uric acid;
- sulfates;
- chlorides;
- ammonia ions.
It does not matter what total volume of fluid enters the body per day - the structural elements of the kidneys remove all metabolic products. If a person drank a small amount of water, then his urine will be saturated with mineral compounds. This means that the specific gravity of the urine is increased, and the patient has hyperstenuria.
With an increased content of fluid in the body in the secondary urine, the concentration of dry residue is relatively low. With each urination, not only metabolic products are excreted, but also excess fluid. Thus, there is a formation of low concentrated urine with a low specific gravity of urine - hypostenuria.
Determining the specific gravity of urine is an important part of laboratory tests.
Determination of specific gravity of urine
Urine analysis to determine the specific gravity is carried out using a special urometer device, or hydrometer. Carefully, along the wall, urine is poured into the cylinder. If a small amount of foam has formed, then it should be removed by blotting with filter paper. The device with urine is immersed in the liquid, while the laboratory assistant makes a small effort to eliminate vibrations. The relative density of urine is determined by the level of the lower meniscus of the hydrometer scale. The walls of the cylinder should not be in contact with the urometer, so its diameter is smaller than the diameter of the cylinder.
In some diseases of the urinary system (for example, neurogenic bladder dysfunction), urine is taken from the patient using a catheter. The resulting volume is measured in a few drops, and it is diluted with distilled water, and after determining the relative density of urine, the degree of dilution is taken into account in the calculations.
If there is very little urine taken for analysis, then both qualitative and quantitative parameters are used in the studies:
- A balanced mixture of benzene and chloroform is placed in the cylinder.
- Add a drop of urine.
- With hypostenuria, the sample is distributed over the surface of the mixture, with hyperstenuria, it will sink to the bottom of the vessel.
- By adding benzene or chloroform in parts, the sample is ensured to be exactly in the middle of the liquid level.
- The relative density of urine will be equal to the specific gravity of the solution determined by the urometer.
All hydrometers are calibrated at 15°C. Therefore, when calculating, a correction is made for the ambient temperature. When it rises, a person's need for fluid intake increases significantly, and when it decreases, they decrease. This affects both the average daily volume of urine excreted and its relative density.
Using a urometer, the specific gravity of urine is determined
Normal specific gravity
The specific gravity index characterizes the functional activity of the kidneys by dilution or concentration of urine. It directly depends on the needs of the human body, the saturation of secondary urine with metabolic products, and the ambient temperature. The relative density of urine is a variable value, changing an arbitrary number of times per day. These changes are driven by the following factors:
- the use of spicy, salty, fatty, fried foods;
- increase or decrease in the amount of fluid you drink;
- profuse sweating due to illness or when the ambient temperature rises;
- release of fluid during respiration.
The relative density of urine should normally vary between 1.015-1.025 in an adult healthy person. The specific gravity of urine in children differs from adult rates and depends on the age of the child. In analyzes taken immediately after the birth of the baby, the lowest relative density of urine is recorded - about 1,010. As the child grows, the specific gravity of urine also gradually increases.
The specific gravity of morning urine is normal for men and women is about 1.02. As a rule, this is the highest indicator of dry residue content in urine per day.
At night, a person's breathing is slowed down, sweating is reduced, and there is no replenishment of the fluid level. Therefore, for testing, such urine is the most informative sample.
Relative density above normal
Increased urine density occurs when certain pathological processes are present in the human body. Hyperstenuria is manifested by increasing swelling, especially often such a symptom causes glomerulonephritis or chronic renal failure. With various diseases of the endocrine system, the specific gravity of urine increases significantly. There is a certain relationship between the violation of the production of hormones and a decrease in the fluid content in the human body.
Hyperstenuria can appear in men and women for the following reasons:
- With significant fluid loss as a result of vomiting, prolonged diarrhea, blood loss, extensive burns.
- With abdominal trauma and intestinal obstruction.
- With toxicosis in pregnant women.
- Diseases of the urinary system in acute or chronic form.
- The use of antibiotics in high doses.
There are many factors that lead to an increase in the relative density of the solids in the urine. Specialists distinguish between pathological and physiological causes of hyperstenuria. Pathological factors include endocrine diseases that occur with metabolic disorders, as well as diseases of the genitourinary system. Physiological causes are quite natural, do not require medical intervention. These include profuse sweating, thirst after eating salty or spicy foods.
Despite the fact that the causes of increased are very different, there are common symptoms of hyperstenuria:
- decrease in the volume of urine released with each urination;
- changing the color of urine to darker;
- the appearance of an unpleasant specific odor;
- the occurrence of edema of various localization;
- increased weakness, fatigue, drowsiness;
- pain in the abdomen and (or) lower back.
In young children, high urine density is often associated with the presence of congenital or acquired diseases of the urinary system. Also, babies are prone to the appearance of intestinal and gastric infections due to high vascular permeability and immunity that has not yet been fully formed. In case of poisoning, fluid loss occurs as a result of vomiting and diarrhea, which leads to hyperstenuria.
The clinical picture of diabetes mellitus is characterized by an increase in the glucose content in urine. The relative density will be higher if an excess concentration of proteins and their breakdown products is found in the urine. To identify the true cause of such a violation, several tests are required, with the help of which the doctor will evaluate the functional activity of the kidneys.
The specific gravity of urine can be determined at home using test strips.
Specific gravity below normal
After suffering infectious pathologies or diseases of the gastrointestinal tract, doctors recommend that the patient increase the volume of water consumed to replenish the body's fluid supply. This leads to hypostenuria - a change in the relative density of urine below normal. This factor in reducing the concentration of dry residue in urine is considered normal, physiological, as well as drinking plenty of water in hot weather, as well as after taking herbal or medicinal diuretics.
Pathological causes of hypostenuria include:
- Neurogenic diabetes insipidus, in which the synthesis of vasopressin is disrupted or its secretion by the pituitary gland (an appendage of the brain) is reduced. Patients without treatment are diagnosed with permanent dehydration.
- Nephrogenic diabetes insipidus. Violations occur at the level of cells of the distal nephron tubules, which do not respond to antidiuretic hormone.
- Diabetes insipidus of pregnant women, disappearing after the birth of the child.
- Nervous diabetes insipidus. It develops against the background of stressful situations or prolonged depression.
- Chronic diseases of the urinary system, in which there is a violation of the processes of filtration and excretion of urine.
- An acute inflammatory process that affects the tubules of the kidneys is pyelonephritis.
The norm of the specific gravity of urine is 1.015, if the indicator falls below, then the doctors ascertain hypostenuria. This condition requires further careful diagnosis to identify the cause of the decrease in the functional activity of the kidneys, their ability to concentrate the dry residue.
This process is directly dependent on the production of vasopressin, an antidiuretic hormone that regulates the reabsorption of fluids in the structural elements of the kidneys. The absence of vasopressin or a decrease in its concentration provokes the formation of increased volumes of urine with a low density.
You can read more about the causes of low specific gravity of urine.
Functional trials
To assess the functional state of the kidney, one laboratory analysis of urine is not enough. The relative density can change throughout the day, therefore, to more accurately determine the ability of the kidneys to accumulate compounds, functional tests are carried out. Some evaluate the ability of the urinary system to concentrate urea and its salts, while others - to allocate them from the human body.
Zimnitsky's test
The analysis evaluates the functional activity of the kidneys in women and men without changes in the drinking regimen. A person urinates every three hours, collecting eight urine samples by the end of the day. Using a urometer, the relative density of urine and the resulting volume are determined. The resulting result shows a normal difference between diuresis at different times of the day: the night should be approximately 30% of the daytime.
concentration test
The study is based on a change in the patient's diet: the use of any liquid is completely excluded from it for a day. To prevent hunger, protein foods are allowed. Some patients find it difficult to tolerate such a diet, and they are allowed to drink a few sips of water. Urine is collected every four hours so that doctors can evaluate its relative density and physical parameters. If the indicators fluctuate between 1.015-1.017, then the kidneys are not coping with their function of concentrating urine. A decrease in readings to 1.01 indicates the development of isosthenuria, a condition in which the kidneys lose their ability to concentrate urine.
If a person regularly takes laboratory tests, including to determine the relative density of urine, this means that he takes care of his health. The sooner a violation in the work of the kidneys is detected, the higher the likelihood of a complete cure.