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How to increase the density of urine. Determination of specific gravity of urine

Specific gravity is one of the physical indicators appearing as a result. The reasons for its deviation from the norm may be the features of the diet. However, sometimes an increase or decrease in the density of urine requires special tests to detect the presence of pathology.

Specific gravity of urine - what is it

The fluid excreted from the body is secondary urine. Unlike primary (similar in composition to blood plasma), it does not contain useful substances. It consists only of an excess volume of fluid and waste products (urea, acids, urobilin and salts - chlorides, sulfates and phosphates).

Healthy kidneys must cope with the task of excreting metabolic products in conditions of ingestion of both small and significant amounts of fluid. In the first case, the urine should become more dense, and in the second - diluted.

The specific gravity (density) of urine is a value that characterizes this ability of the kidneys - to ensure the constancy of the mass of metabolic waste excreted with any volume of secondary urine.

Norms in adults and children

The total volume of fluid involved in metabolic processes is not a constant value. Factors such as:

  • air temperature;
  • drinking regime;
  • current time of day;
  • the presence of salty or spicy food in the menu;
  • the amount of fluid released during sweating and breathing.

However, in a normal adult, the variations should be in the range of 1.014-1.025 g / liter (normostenuria).

During pregnancy, the spread of daily values ​​\u200b\u200bmay be wider - 1.003-1.035. The reasons for this are partly toxicosis, nausea and vomiting, which causes dehydration.

If there is a deviation of the indicator (in the analysis form -), the following are distinguished:

  • - SG fluctuations within limited limits - 1.010-1.012;
  • hypostenuria– decrease in SG less than 1.010 (1.008);
  • hyperstenuria– increase in SG to 1.025 (1.030) and higher.

An increase in density can also be initiated by factors such as:

  • the presence of sugar in the blood– 1% per 0.004 g/liter;
  • the presence of protein in urine– 3g/liter of protein corresponds to an increase in SG of 0.001.

Normal specific gravity values ​​for children can be tabulated:

In the general case, the excess of the norm for children is the value of the specific gravity of 1.020 g / liter.

Reasons for increasing the specific gravity

All existing reasons for the output of the urine density indicator beyond the normal range can be divided into physiological and pathological. The first factors independent of gender and age include:

  • a feature of the drinking regime, expressed in insufficient fluid intake during the day:
  • taking significant doses of drugs that are actively excreted with urine: (or rather, certain groups of diuretics that increase the excretion of urea and other substances with urine), as well as antibiotics;
  • dehydration caused by frequent vomiting or diarrhea, as well as profuse sweating in hot weather or during intense physical exercise;
  • burns of large areas of the body and trauma to the abdomen - naturally, both of these conditions require therapy, but the mechanism for the appearance of hyperstenuria is generally natural here.

Among the diseases that can cause a change in the laboratory indicator of SG, there are:

  • heart failure, with accompanying edematous manifestations;
  • diabetes mellitus, accompanied by a high concentration of sugar in urine;
  • inflammatory diseases of the kidneys or lower urinary tract;
  • or, on the contrary, start ;
  • (hyperstenuria is combined with oliguria - a decrease in the amount of urine);
  • diseases accompanied by ().
  • endocrine pathologies.

Hyperstenuria in pregnant women

Laboratory parameters in women during the period of bearing a child can differ significantly from the norm, both due to physiological and treatment-requiring reasons. An increase in specific gravity may appear in connection with such phenomena as:

  • toxicosis and accompanying dehydration, as well as a violation of the water-salt balance;
  • preeclampsia (preeclampsia) - an increase in the specific gravity of urine occurs in conditions of extensive edema, a small amount of urine excreted and the presence of a large amount of protein in it.

Hyperstenuria in children

Impressive figures characterizing this indicator can occur in babies, both against the background of common causes, and have specific prerequisites:

  • congenital or acquired pathologies of the urinary organs;
  • frequent poisoning and gastrointestinal infections leading to diarrhea and vomiting.
  • in infants, an increase in the specific gravity of urine may be associated with the peculiarities of the mother's diet - an excess of animal proteins, fatty foods, offal in it.

Reasons for the decrease in specific gravity

A change in the indicator should not cause concern if the decrease occurred under the conditions:

  • abundant intake of fluid in the body;
  • taking non-fast groups of diuretics (although a doctor's consultation may be required here);
  • an unvaried diet characterized by insufficient protein intake. This also includes prolonged starvation, dystrophic conditions.

In the presence of a pathological process, urine becomes less dense in the absence of an excessive (but not pathological) drinking regimen.

This can happen under the following conditions:

  • involuntary polydipsia - excessive fluid intake, not caused by physiological needs. The disorder often accompanies mental disorders or diabetes insipidus;
  • central or renal diabetes insipidus;
  • diseases of the central nervous system - encephalitis, meningitis;
  • chronic renal failure;

In turn, provoke the development of diabetes insipidus of various types can:

  • hereditary pathological conditions;
  • head injuries and surgical interventions;
  • infectious diseases;
  • malignant neoplasms in brain tissues, accompanied by metastases;
  • , including .

Features in pregnant women and children

In newborns, the specific gravity of urine often does not exceed 1.015-1.017. This value is considered normal during the first month of a child's life.

Women may experience transient diabetes insipidus during pregnancy. It either does not require treatment at all, or allows symptomatic therapy according to the type of central syndrome. If it is of a nervous nature, a psychiatric consultation may be required.

Diagnostic methods

Unable to accurately determine specific gravity due to the fact that the concentration of substances dissolved in urine during the day can vary significantly. It is not within his power to differentiate the cause of the violation that has arisen. Therefore, the following types of functional research are used:

  • - a type of diagnosis, during which the ability of the kidneys to excrete fluid, as well as to concentrate and dilute urine, will be determined. It is carried out without changing the drinking regimen and consists in collecting 8 portions of urine for knocking (after 3 hours). Each portion is measured by the volume of urine and its specific gravity. The result of the analysis will be the spread of density figures per day and the difference between daytime and nighttime diuresis. Further analyzes are prescribed only in case of a doubtful result of the Zimnitsky test or if obvious deviations are found;
  • concentration test (with dry food)- is carried out with the elimination of liquid foods and drinks from the patient's diet. Collect several daily portions of urine from 9 to 21 pm and one night. The test is not always advisable and has contraindications;
  • breeding test- this tests the ability of the kidneys to dilute urine with excessive fluid intake. To do this, the person being examined needs to drink a certain amount of water, calculated based on the weight of his body. There are groups of patients in whom the study is carried out with caution or is completely contraindicated.

The specific gravity of urine is an indicator in which the average person rarely shows increased interest. However, it can also be a source of information needed by the clinician in evaluating kidney function and sometimes in diagnosing non-renal pathologies.

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 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.

The specific gravity (second name - relative density) of urine is an indicator that characterizes the work of the kidneys and makes it possible to assess how well they cope with the filtering function and excretion of unnecessary compounds from the body. By studying the density of the biological fluid, the laboratory assistant determines what is the content in it:

  • Creatinine.
  • Urea.
  • uric acid.
  • sodium and potassium salts.

It is by the values ​​of these parameters that the above criterion is calculated.

Specific gravity of urine: normal indicators for men, women and children

Determination of the density of urine is carried out in a laboratory using a special device - urometer. In order for the data obtained to be true, the patient must correctly collect material for the study (do not drink alcohol the day before, a lot of liquid).

Slight fluctuations in the parameter during the day is a normal physiological reaction. This is due to changes that occur during eating, drinking water, doing heavy physical work, resting, sweating, etc. Under different conditions, the kidneys of a healthy person excrete urine, the density of which is normally equal to from 1.010 to 1.028.

In men and women who do not have diseases of the urinary system, with moderate physical exertion, the specific gravity of morning urine is most often from 1.015 to 1.020. As for children, their figure may be slightly lower.

For children, the norm option is from 1.003 to 1.025. In the first week of life, the specific gravity of the urine of the child should be within up to 1.018, starting from the second week and until the end of the second year - from 1.002 to 1.004.

Later, the indicator begins to rise and, during normal kidney function, is already from 1.010 to 1.017. In children 4-5 years of age, the density is 1,012-1,020 . For children over 10 years old, it should be in the range from 1.011 to 1.025.

Causes of a decrease in the specific gravity of urine

If the density of the biological fluid is below normal, they talk about hypostenuria. This does not necessarily mean that the person is sick. Physicians are aware of cases where such a deviation was the result of the patient drinking an excessive amount of liquid shortly before the laboratory test.

Also, the use of any diuretic drugs leads to hypostenuria. The doctor must be warned about this factor in advance so that the data obtained are not misinterpreted.

What diseases cause a decrease in the specific gravity of urine

If we talk about the pathological causes of hypostenuria, they are as follows:

  • Diabetes.
  • Polydipsia (usually seen in people with unstable mentality)
  • Neurogenic and nephrogenic diabetes insipidus.
  • Inflammation of the renal tubules.
  • The presence in the body of unresolved infiltrates.
  • Untreated or complicated pyelonephritis.
  • Chronic renal failure.
  • Compliance with an overly strict diet, lack of vitamins, trace elements and minerals in the diet.
  • The presence of nodular formations on the renal tissues.
  • Hormonal failure (typical for women of childbearing age, as well as during menopause).

Many patients with a significant decrease in the described indicator complain of:

  • The appearance of edema on different parts of the body, limbs.
  • Pain in the lower abdomen or lower back.
  • Decrease / increase in the volume of urine separated.

All these symptoms indicate problems with the kidneys, so when they appear, you should contact a qualified doctor as soon as possible and undergo an examination.

What to do with a low specific gravity of urine

If the specific gravity of urine is much lower than normal, first of all, it is necessary retake laboratory tests. Be sure to take a responsible attitude to the re-collection of biological fluid, on the eve of the diagnosis, do not drink too much fluid. If other indicators are normal, then most likely the person does not have any kidney disease.

If, in addition to low density, there are other deviations in laboratory tests, a comprehensive examination is mandatory. What it will include, the therapist or urologist must decide. Usually, patients are given referrals for an analysis according to Zimnitsky, which allows you to establish differences in urine density at different times of the day.

Specific gravity of urine during pregnancy

It is considered normal if the relative density of urine in the expectant mother is from 1.010 to 1.029. The parameter reduction is provided by:

  • Excessive fluid intake.
  • Edema.
  • Hormonal surges.
  • Kidney pathologies (nephropathy)
  • Toxicosis.
  • Frequent urination.

If the criterion, on the contrary, is increased in a pregnant woman, the gynecologist may assume the presence of:

  • Diabetes.
  • Fluid deficiency, dehydration.
  • Inflammation of the kidneys.
  • Severe toxicosis / gestosis.

The expectant mother should not worry if the results of the analysis were unsatisfactory. The analysis should be retaken as soon as possible. Only if the re-diagnosis confirms the concerns that have arisen, the measures necessary to determine the cause of the condition will be carried out.

The specific gravity of urine is increased - causes and what to do

An increase in the specific gravity of urine in medicine is called hyperstenuria. Usually this problem develops against the background of a decrease in the amount of separated biological fluid. It can be provoked by:

  • Severe vomiting, nausea.
  • Inadequate fluid intake, dehydration.
  • The introduction of a radiopaque substance into the patient's body on the eve of a laboratory study.
  • Proteinuria (presence of protein) in nephrotic syndrome.
  • Diabetes.
  • Taking large doses of antibiotics.
  • Inflammation of the organs of the genitourinary system.
  • Toxicosis during pregnancy.

Hyperstenuria is characterized by symptoms such as:

  1. Discomfort in the abdomen.
  2. Pain in the lower back.
  3. The formation of edema for unknown reasons.
  4. A sharp decrease in single portions of excreted urine.
  5. Weakness, fatigue.

With hyperstenuria, as with hypostenuria, the patient should undergo a Zimnitsky test to understand if there are abnormalities in the work of the kidneys and get a complete picture of their functioning.

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 index (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 fluid excretion 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 a small amount of it, 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 is excessive drinking of water, 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 rises 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. According to 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.

General clinical tests help diagnose many diseases. The specific gravity of urine is a standard for general urine analysis, which indicates the ability of the kidneys to collect, purify and excrete primary urine. Deviations in this indicator allow us to talk about many diseases, increase the likelihood of their early detection, which means that treatment can be started on time.

Laboratory study of urine for specific gravity allows you to see a number of pathologies of internal organs.

How is urine formed?

The appearance of urine in the kidneys takes place in three stages: filtration, secretion. The first of these occurs in the renal glomeruli. Here, salts, toxins, glucose, creatinine and other chemical substances are filtered out of the blood. This results in 180 liters of primary urine. The second stage occurs in the tubules of the kidneys and is characterized by the return of the nutrients needed by the body to the bloodstream. At the last stage, hydrogen, potassium, ammonia and drugs enter the urine. After that, 1.5-2 liters of secondary urine is formed, which enters the bladder and is excreted.

Reasons for urine specific gravity analysis

Urine examination demonstrates the ability of the kidneys to collect, purify and excrete it. This indicator is called specific gravity, which is determined by the abundance of substances soluble in it and depends on the amount and nature of the food and liquid taken. A low specific gravity of urine will be observed if the body receives little water, and, conversely, with increased hydration.

Urine analysis


When analyzing urine for specific gravity, values ​​​​are compared by 7 parameters.

A general urine test makes it possible to determine the physical and chemical properties, as well as the results. Normal urine has a light straw color. It is transparent, with a slight odor and a specific gravity of 1012-1025. The ratio of daytime and nighttime diuresis is 3:1. The chemical properties of urine, as well as the number of sediment elements, will differ depending on the age and sex of the patient. Most of the normal analysis indicators are shown in the table.

Urine density norm

Urine contains uric acid, its salts, creatinine and other elements. Their abundance determines the density of urine. The determination of specific gravity is carried out in the laboratory with a urometer or at home using a test strip. Normally, in an adult, it should be in the range of 1012-1025. In a child up to a year old, the concentration is lowered to 1002, but as it grows, the indicator increases and reaches adult norms by the twelfth year. The determination of the specific gravity of urine is carried out in a portion collected in the morning on an empty stomach. The relative density of urine is a variable value. Its increase or decrease is due to:

  • food intake;
  • temperature conditions of the environment;
  • loss of fluid through perspiration and breathing.

Increased urine density


An overestimated specific gravity of urine occurs with glomerulonephritis, heart failure, diabetes mellitus, diathesis.

The deviation of this sign above the norm is hyperstenuria. Such an increase may be due to a lack of water in the body or a reaction to the appearance of edema. It is observed with oliguria in patients with acute glomerulonephritis, heart failure, edema, as well as during pregnancy with toxicosis, diabetes mellitus, hypovolemic conditions,. An increased specific gravity of urine can be after intravenous infusions, taking certain medications, thermal damage, and prolonged dyspeptic manifestations. With hyperstenuria, a rather small daily diuresis, the color of the urine becomes saturated, a pungent odor appears. There are swelling in various parts of the body, pain in the abdomen and lower back, high fatigue.

Decreased density of urine

If the specific gravity of urine is lowered, then they speak of hypostenuria. The condition can develop under the influence of extrarenal causes, for example, due to a lack of secretion of antidiuretic hormone or renal - associated with abnormalities in the functioning of the glomerular and tubular nephron and a decrease in their cumulative capacity. In this case, the patient notes symptoms such as thirst, increasing swelling in the head and limbs, lumbar pain, and itchy skin. A decrease in the specific gravity of urine below the norm is manifested if diagnosed:

  • diabetes insipidus;
  • chronic kidney failure;
  • parenchymal kidney disease - pyelonephritis, glomerulonephritis;
  • kidney cyst;
  • polydipsia.

The density of urine is an indicator that changes physiologically and pathologically. It is possible to establish the cause and range of the deviation using a general analysis and subsequent consultation with a specialist.

What is a stably reduced density level?

Reduced urine density in all daily portions is characteristic of pyelonephritis in remission, insufficient kidney function, and diuretic therapy. Hyperisosthenuria is a state when the level of density is equally increased, observed in diabetes mellitus, hypovolemic conditions, and uric acid diathesis. Hypoisostenuria - means the presence of severe pyelonephritis and tubulopathies.