Diuresis represents the volume of urine that is formed in the human body over a certain specific time. The most commonly used concept daily diuresis– that is, measuring the volume of urine produced in 24 hours, as well as minute diuresis. The latter value is usually used when studying renal function using method ground clearance.

Daily urine output of an adult healthy person is about 65-75% of the volume of fluid drunk per day. To select all necessary products the kidney needs at least 500 ml, so it is easy to calculate that a person needs to consume at least 800 ml of fluid per day, which is the lower threshold. With a normal water regime, which involves drinking 1-2 liters of liquid, daily diuresis will be from 800 to 1500 ml, and the minute diuresis will be 0.55-1 ml, respectively.

Various pathological conditions can affect urine output, and significantly. They are distinguished - urine output less than 200 ml per day with normal water regime, oliguria– excretion of no more than half a liter of urine per day, and polyuria– excretion of up to three liters of urine during normal urine consumption.

Also distinguish night And daily diuresis. The ratio of daytime to nighttime diuresis in a healthy person is usually 3 to 1 or 4 to 1. Nocturia is a pathology that develops when this ratio changes in favor of nocturnal diuresis.

In addition, diuresis is distinguished depending on the volume of urine and the amount of active substances released:

  • Water
  • Antidiuresis
  • Osmotic diuresis

Water diuresis is characterized by a large volume of urine with an extremely low content of osmotic substances. It represents a selection hypoosmolar urine. In healthy people, water diuresis can develop against the background of consuming a large volume of liquid, during the transition to a state of weightlessness, as well as to bed rest from normal physical activity. It is also characteristic of postencephalitic, psychogenic and primary polydipsia, in the terminal stage of chronic kidney disease, chronic alcoholism, hypercalcemia, hypokalemia, renal failure diabetes mellitus, as well as in the phase of swelling swelling.

Antidiuresis is characterized by a small volume of urine together with a high concentration of active osmotic substances.

Osmotic diuresis is the release of a large amount of urine due to increased excretion of active substances. It usually develops due to excessive loading of the nephron with active substances of exogenous (simple sugars, mannitol) and endogenous origin (bicarbonate, urea, glucose). When the presence of active substances in the lumen of the tubules is observed in concentrations that exceed the ability for their reabsorption, as well as exogenous non-reabsorbable substances, an accelerated flow of fluid occurs. Thus, a large volume of urine is released with a high concentration of osmotic active substances in it. The sodium content, for example, is 50-70 mmol/l. As a rule, this condition can develop with the use of osmotic diuretics, chronic renal failure, and diabetes mellitus.

Research on human waste products is informative and accessible in medicine. Daily diuresis is an object for this type of laboratory diagnostics, such as daily urine analysis. It shows the daily amount of urination (including nighttime diuresis and daytime diuresis), determines the presence of substances indicating certain abnormalities. Urine output is used to evaluate performance internal organs in newborns and up to old age.

Types of daily urine output tests

Why is it necessary to study daytime diuresis and nighttime diuresis? What does it give? Urine is tested to calculate the concentrations of certain substances in the body:

  1. Protein (called daily proteinuria analysis). The loss of protein is not taken into account, but its increase should be considered a sign of life-threatening diseases.
  2. Collecting test material for sugar is often prescribed to patients with diabetes.
  3. Control of oxalate content is carried out in diseases of the gastrointestinal tract.
  4. Urine is checked for the presence of cortisol inclusions in it. If they are elevated, then we can talk about the presence of Itsenko-Cushing syndrome.
  5. Metanephrines (called analysis: urine for salturesis). Donation is necessary if a benign tumor is suspected, which progresses slowly and does not have obvious manifestations.

When and to whom is it done?

If you have diabetes, it is mandatory to take a urine sample to determine kidney disease.

It is necessary to submit urine for daily analysis when checking the functioning of the kidneys, to control the substances released during the day. A daily urine test is required if:

  • diabetes mellitus, then 24-hour urine analysis will help control the patient’s glucose level;
  • kidney diseases (when water balance is disturbed, diuresis outflow or failures occur in the performance of their functions);
  • pregnancy, then a daily urine test helps determine how a woman’s body copes with stress.

Preparation: how not to distort the results

No special training is required to collect urine. Collection rules will be explained medical worker, focusing the patient’s attention on the fact that urine collection requires care and correct actions. There are several requirements that the analysis takes into account:

  1. It is necessary to maintain an acceptable drinking regime so that the level water balance was familiar.
  2. The use of diuretics and certain medications (for example, aspirin) is prohibited.
  3. It is not recommended to eat beets, carrots and other natural dyes that affect the color of urine for analysis.
  4. Alcoholic beverages are prohibited.
  5. For women, urine collection for daily diuresis during menstruation is contraindicated.
  6. It is not recommended to have sexual intercourse 12 hours before collecting material.

How to collect from children and adults: collection rules

To ensure the accuracy of the analysis, urine must be collected following the collection rules.

How to properly collect urine for analysis? The research will be correct if you adhere to the following actions:

  • to check daily diuresis in children and adults, urine is collected in a sterile container with divisions to calculate the volume;
  • for collection, it is necessary to wash the external genitalia so that unnecessary substances do not get out of them;
  • collection of daily urine begins without the first portion; determination of daily urine output does not require its infusion;
  • Urine should be stored in the refrigerator;
  • the entire container is not needed in the laboratory, you can estimate at home how much the daily norm is;
  • from the total mass, up to 200 ml are poured, which are delivered to the laboratory, indicate the time (no hourly clarification is required), from when and at what time the urine was collected and the total volume (determine it yourself), how old the patient is;
  • sometimes you need an indicator such as weight, sometimes height is also measured.

Performance standards: within what limits are they assessed?

In the table for assessing urine per day, the state of water balance and calculating daily diuresis, laboratory assistants can find all the standard values. The correct results are recorded on a special sheet and sent to the doctor for subsequent diagnosis or the appointment of additional diagnostic examination methods. The algorithm of actions for assessment includes the following basic indicators, the value of which determines the conclusion:

  • total volume of urine excreted per day: the normal change in daily diuresis for an adult man is 1-2 l, for women - 1-1.6, the normal daily diuresis for children is no more than 1 l;
  • rate of diuresis (hourly control);
  • color, transparency, density (normally, in adults and children, urine should be without turbidity);
  • in a healthy person, hemoglobin should be absent in a urine test per day;
  • measurement of glucose when submitting material for sugar (norm - 1.6 mmol/day);
  • creatinine count (if it is elevated, this indicates acute infections, hypothyroidism, etc.), the value of which should fluctuate between 5.3-16 mmol/day. for females and 7−18 for males;
  • pH is a characteristic whose change affects the pH of the blood;
  • measuring urea level ( normal indicator for all categories of the population 250-570 mmol, deviations are a signal of disease);
  • measure oxalates, the normal value of which ranges from 228−626 µmol/day;
  • check for the presence of protein (daily proteinuria): acceptable excretion is 0.08-0.24 g/day;
  • daily urine is checked for bilirubin, which indicates blood or liver diseases;
  • human diuresis is examined for the presence of urobilinogen (no more than 10 µmol).

Daily diuresis is one of the criteria proper operation kidney Urine excreted per day is usually counted. Normally, in an adult, the amount of urine excreted is ¾ or 70-80% of the fluid consumed. In this case, the amount of moisture that enters the body along with food is not taken into account. Therefore, if a person should drink about two liters of liquid per day, then the volume of urine excreted is at least 1500 ml.

In order to completely remove decay products from the body, at least half a liter of urine must be released. Determining daily diuresis is also important for studying renal function by calculating clearance. To do this, the patient must collect all urine during the day into a special container with graduated walls.

However, he should not take diuretics during the procedure and three days before it. It is also important to record not only the volume of urine excreted, but also the volume of liquid drunk (water, tea, coffee). Measuring daily diuresis usually begins from 6 a.m. to the same time the next day.

Types of diuresis

Depending on the amount of urine excreted, there are:

  • polyuria – the amount of fluid excreted exceeds 3 liters. This may be due to disruption of the hormone vasopressin, also called antidiuretic hormone. Sometimes this condition occurs when the concentrating ability of the kidneys is impaired, with diabetes mellitus;
  • oliguria – the amount of fluid secreted has sharply decreased to 500 ml or less;
  • anuria, in which urine output in an adult does not exceed 50 ml in the entire 24 hours.

Urine flow occurs unevenly throughout the day. Therefore, daytime and nighttime diuresis are distinguished, the ratio of which is normally 4:1 or 3:1. If nocturnal diuresis prevails over daytime diuresis, then this condition is called nocturia.

It is also important for patients to evaluate not only the amount of fluid secreted, but also its composition. If the concentration of osmotically active substances in the urine exceeds the norm, then such diuresis is called osmotic. This condition indicates an overload of nephrons with substances such as glucose, uric acid, bicarbonate and others. Their increase in the blood is associated with other organic pathology.

The daily amount of urine with a reduced concentration of osmotically active substances is called water diuresis. In a healthy person, this condition can be observed with an increase in fluid intake.

Decreased urine output

A decrease in the daily amount of urine in a healthy person can be observed during the hot season, when most of the liquid is excreted through sweat. This condition also occurs when working in high temperatures, loose stools or vomiting.

But a decrease in urination to 500 ml per day or less is a poor prognostic sign for many diseases. The development of oliguria or anuria occurs when sharp decline circulating blood volume and drop in blood pressure. They develop with heavy bleeding, uncontrollable vomiting, profuse loose stools, and various states of shock.


Oliguria occurs with the development of acute renal failure. This life-threatening complication occurs with nephritis, acute massive hemolysis, damage to the renal parenchyma. With a massive infectious process, kidney damage is possible due to bacteremia.

Differential diagnosis of oliguria must be carried out with ischuria. This condition develops due to mechanical blockage of any part of the urinary system. This can be caused by the growth of a tumor process, blockage of the lumen of the ureter with a stone, or narrowing of the urinary tract. In men common cause ischuria is prostate adenoma, especially in older people.

Increased urine output

Polyuria is an important diagnostic criterion for a number of endocrine, cardiac or metabolic diseases.

There are renal and extrarenal polyuria. The first is caused directly by kidney disease, which affects the distal parts of the nephron. This symptom can occur with pyelonephritis and renal failure.


There are many more reasons for the development of extrarenal polyuria. Increased urine production occurs in diabetes mellitus. This occurs when glucose enters the urine, which draws fluid onto itself, since it is an osmotically active substance.

In diabetes insipidus, the genesis of polyuria is a violation of the production of vasopressin, which is responsible for retaining the required amount of fluid. Daily diuresis also increases with Conn's syndrome (hyperaldosteronism).

Extrarenal polyuria also occurs when there is an increase in fluid in the vascular bed. For example, with intravenous drip administration of solutions with diuretics, that is, forced diuresis. The doctor prescribes diuretics medications to reduce swelling. Excess liquid from the tissues returns to the bloodstream, and its excess is excreted along with urine.

Urine formation during pregnancy

A change in the amount of daily urine is prescribed when there is a suspicion of hidden edema or a threat of developing preeclampsia or eclampsia. For pregnant women, daily diuresis is prescribed according to indications; the analysis is not included in the list of mandatory ones for expectant mothers.

Diuresis(diuresis; Greek diureō to excrete urine) - the amount of urine excreted over a certain period of time (day, hour, minute). In a healthy adult, daily D. is up to 75% of the amount of fluid drunk. The minimum volume of urine required for the kidneys to excrete the total amount of metabolic products formed during the day is 500 ml. Thus, the volume of fluid consumption should be at least 800 ml per day. Under standard conditions water regime(consumption per day 1 1/2 -2 l liquid) D. is approximately 1200-1500 ml per day (for men 1000-2000 ml, for women 1000-1600 ml). In children, D. depends on the age of the child. A newborn's bladder typically contains a small amount of urine, which is released immediately after birth. In the next 2-3 days, the daily D. is 20-40 ml urine. Sometimes in the first 2-3 days of a newborn’s life, anuria is observed due to insufficient fluid intake. Lack of urination in these cases is not a pathological condition. Starting from the 4th day of life, the daily amount of urine gradually increases, reaching an average of 150 by the end of the 1st week. ml per day, and by the end of the 2nd week - 240 ml. By the end of the first year of life, a child’s daily D. averages 450 ml, from 1 to 5 years - 750 ml, from 5 to 10 years - 950 ml, from 10 to 15 years - 1200 ml. This indicator in children over 1 year of age can be approximately calculated using the formula:

600 + 100× ( X - 1)ml in 24 h,

Where X- the age of the child in years.

Under pathological conditions, the amount of urine excreted can vary significantly. Considered pathological D. in an adult below 500 ml and above 2000 ml against the background of the usual drinking regimen. Discharge less than 400-500 ml urine is considered as oliguria, less than 200 ml urine - like anuria. Daily D. exceeding 2000 ml urine is characterized as polyuria. The latter may be due to the lack of circulating vasopressin - antidiuretic hormone (ADH) and (or) impaired renal concentrating ability. In clinical practice, polyuria due to insufficient ADH production is most often detected when diabetes insipidus, less often with electrolyte disorders (hypokalemia, hypercalcemia) and prolonged polydipsia.

Polyuria due to impaired concentrating ability of the kidneys is observed in a number of hereditary kidney diseases (renal diabetes insipidus, renal tubular acidosis, Fanconi syndrome); excessive fluid consumption (with psychogenic polydipsia, sugar e); chronic kidney diseases; electrolyte disturbances (hypokalemia, hypercalcemia and hypercalciuria); osmotic diuresis (for chronic renal failure, glucosuria, after eliminating urinary tract obstruction).

For the listed diseases and pathological conditions, 2 types of urinary disorders are distinguished - moderate and severe polyuria. Moderate polyuria - discharge no more than 3-4 l urine per day against the background of impaired nitrogen excretion function of the kidneys, for example, in chronic renal failure, hypokalemia, hypercalcemia, Fanconi syndrome. Severe polyuria with excretion of about 5 l urine (maximum 10-12 l) against the background of preserved nitrogen excretion function of the kidneys is revealed,

usually with diabetes insipidus, psychogenic polydipsia and familial renal insipidus.

In addition to the quantitative characteristics of D., the rhythm of urine excretion and the content of osmotically active substances in it are important. Throughout the day, urine excretion occurs unevenly in a healthy person, which depends mainly on the drinking regime and physical activity. In clinical practice, the daily rhythm of urine excretion and the concentrating ability of the kidneys are assessed using the Zimnitsky test, which is carried out under standard food and water conditions with the patient’s normal physical activity. 3 days before the test, diuretics are discontinued. When evaluating samples, take into account total urine in all 8 portions, which is the daily D.; calculate daytime and nighttime D. separately and analyze fluctuations relative density urine in collected portions. Normally, the amount of urine excreted per day corresponds to the average values ​​(1200-1500 ml); daily diuresis is 60-80% of the daily amount of urine. The relative density of urine during the day ranges from 1005 to 1025.

Signs of renal dysfunction are changes in the amount (decrease or increase) of urine excreted, increased urination at night (nocturia), and a decrease in the amplitude of fluctuations in the relative density of urine. The latter can be manifested by a state of hyposthenuria, in which the maximum relative density of urine is less than 1020; a state of hypersthenuria, characterized by an increase in the minimum relative density of urine to 1010 or more; a state of isosthenuria, when the relative density of urine in samples is fixed at the level of 1008-1010. To clarify the nature of the disorders, additional research is needed under the conditions of using stress tests to concentrate and dilute urine.

Depending on the amount of osmotically active substances excreted in the urine and the volume of urine, antidiuresis, water and osmotic diuresis are distinguished. Antidiuresis is characterized by the release of a small volume of urine 0.5-0.7 l/day (0.35-0.5 ml/min) with a high concentration of osmotically active substances; the ratio of urine osmolality to plasma osmolality approaches 4. Antidiuresis develops when there is a high concentration of ADH in the blood. The distal tubules and collecting ducts are completely permeable to water under these conditions. At a high concentration of osmotically active substances in the renal interstitium, intense reabsorption of water occurs. In healthy individuals, antidiuresis can be observed during the transition from prolonged hypokinesia to normal physical activity. Antidiuresis is detected with blood loss, after surgical interventions on the organs of the chest and abdominal cavity, with loss of fluid due to vomiting and diarrhea; with heart failure, development of nephrotic syndrome, acute eitis, cirrhosis of the liver.

Water diuresis is characterized by the release of a large volume of urine with a low content of osmotically active substances. Minute D. reaches 12-14 ml, urine osmolality can decrease to 50 mosmol/kg H 2 O, the ratio of urine osmolality to plasma osmolality is less than 1. With aqueous D., the release of ADH is blocked, the distal tubules and collecting ducts are impermeable to water, the osmolarity of the renal interstitium is low. In healthy individuals, water diarrhea develops after consuming a large amount of liquid, during the transition from normal physical activity to strict bed rest, to a state of weightlessness. It is also observed with diabetes insipidus, hypokalemia, hypercalcemia, chronic diabetes,

with polydipsia, acute renal failure, during the period of swelling.

Osmotic D. is characterized by the release of a large volume of urine - up to 10 l/day (up to 7 ml/min) and high daily excretion of osmotically active substances (sodium concentration in urine 50-70 mmol/l); the ratio of urine osmolality to plasma osmolality is higher than 1. The development of osmotic D. is associated with the entry into the proximal nephron of large quantities of endogenous (glucose, urea, bicarbonate) or exogenous (mannitol, simple sugars) osmotically active substances. According to the nature of these substances, endogenous and exogenous osmotic D. are distinguished. Endogenous osmotic D. is detected with decompensated sugar e, exogenous - with the use of osmotic diuretics.

The so-called anionic diuresis, which is observed with high load proximal tubules with unreabsorbed anions, such as ketoacid anions at

In a routine urine test, unless specifically indicated, the amount delivered is not significant and is not noted in the analysis, except in cases where very little urine is delivered, as a result of which some data (for example, specific gravity) cannot be identified.

The amount of morning urine (usually 150 - 250 ml) does not give an idea of ​​daily diuresis and measuring its volume is advisable only for interpreting its relative density. Measuring the amount of urine is important primarily for assessing daily diuresis.

Method for determining the amount of urine

To determine the amount of urine (daily or collected over a certain time, taken with a catheter, etc.), it is poured into measuring cylinders and, holding the vessel at eye level, the amount is noted. The narrower the diameter of the measuring vessel, the more accurate measurement quantities. Therefore, small graduated cylinders are used to measure small quantities. In cases where it is necessary to carry out a microscopic examination of urine, the quantity is measured after collecting the sediment.

The normal amount of urine excreted during the day with a normal mixed diet depends on the age and gender of the patient.

Age norms for daily diuresis
Age Daily diuresis (in ml)
newborn 0 - 60
1 day 0 - 68
Day 2 0 – 82
Day 3 0 – 96
4 day 5 - 180
5 day 20 - 217
Day 6 42 - 268
Day 7 40 - 302
Day 8 59 - 330
Day 9 57 - 355
10 day 106 - 320
Day 11 120 - 217
12 day 207 - 246
15 years 600 - 900
5 - 10 years 700 - 1200
10 - 14 years 1000 - 1500
Adult women 1000 - 1600
Adult men 1000 - 2000

In premature babies and children who are on artificial feeding, slightly greater diuresis.

Largest quantity urine is excreted in daytime with a peak from 15 to 18 hours, and the lowest during the night hours with a minimum of 3 to 6 hours. The ratio of daytime to nighttime diuresis is 3:1 - 4:1.

Clinical significance of daily diuresis

Under various physiological and pathological conditions, daily diuresis can either increase or decrease.

Polyuria

An increase in the daily amount of urine is called polyuria.

Physiological polyuria may be related to:

  • increased drinking regime,
  • eating foods that increase urine output (watermelons, melons, etc.).

Pathological polyuria observed when:

  • resorption of edema, transudates and exudates,
  • after feverish conditions,
  • primary aldosteronism,
  • hyperparathyroidism,
  • diabetes mellitus and diabetes insipidus (up to 4 - 6 l),
  • hydronephrosis (intermittent polyuria),
  • in nervous, mentally excitable children (paroxysmal polyuria),
  • polyuric phase of acute renal failure,
  • after taking certain medications (diuretics, cardiac glycosides).

Oliguria

Oliguria- This is a decrease in the amount of daily urine. Usually, we should talk about oliguria when diuresis decreases below 1/3 - 1/4 of the age norm.

Physiological oliguria According to the mechanism of occurrence, it is prerenal and is observed:

  • in the first 2 - 3 days after birth due to insufficient lactation,
  • with limited drinking regime,
  • when losing fluid through sweat hot weather or when working in hot shops, during physical activity.

Pathological oliguria According to the mechanism of occurrence, it can be prerenal, renal and postrenal.

Prerenal oliguria

At the core prerenal oliguria there is insufficient blood supply to the kidneys due to hypovolemia, which can be caused by:

  • excessive loss of fluid extrarenally (vomiting, diarrhea, increased perspiration during high temperature, shortness of breath),
  • blood loss,
  • loss of fluid through the renal route during an overdose of diuretics,
  • insufficient blood circulation in the kidneys, associated with a decrease in cardiac output in patients with heart diseases (myocarditis, heart defects, etc.).

Renal oliguria

Renal oliguria occurs when the kidneys themselves are damaged. Moreover, it may be due to involvement in the pathological process:

  • glomeruli (various variants of glomerulonephritis),
  • tubulointerstitium (interstitial nephritis),
  • renal vessels (systemic vasculitis, hemolytic-uremic syndrome, embolism).

Postrenal oliguria

Postrenal oliguria occurs when:

  • bilateral urinary tract obstruction ( urolithiasis disease, formation of blood clots during renal bleeding, tumor process in the retroperitoneum or in the bladder),
  • obstruction of the urethra (stricture, stenosis, tumor).

Anuria

Anuria- almost complete cessation of urine output. Anuria is observed when:

  • severe acute kidney failure,
  • severe nephritis,
  • meningitis,
  • severe poisoning,
  • peritonitis,
  • tetany,
  • vulvitis,
  • spinal shock,
  • blockage of the urinary tract by a tumor or stone (retention anuria).

Nocturia

Nocturia- predominance of nighttime diuresis over daytime. Observed when:

  • disappearance of edema (especially in nephrotic syndrome after the disappearance of proteinuria during treatment with glucocorticoids),
  • initial stage of cardiac decompensation,
  • cystitis and pyelocystitis,
  • hypertension.

The daily amount of urine with nocturia may remain within normal limits.

Literature:

  • A. Ya. Althauzen "Clinical laboratory diagnostics", M., Medgiz, 1959
  • A. V. Papayan, N. D. Savenkova "Clinical nephrology of childhood", St. Petersburg, SOTIS, 1997
  • L. V. Kozlovskaya, A. Yu. Nikolaev. Tutorial on clinical laboratory research methods. Moscow, Medicine, 1985
  • Manual of clinical laboratory diagnostics. (Parts 1 - 2) Ed. prof. M. A. Bazarnova, Academician of the USSR Academy of Medical Sciences A. I. Vorobyov. Kyiv, "Vishcha school", 1991
  • Handbook "Laboratory research methods in the clinic" ed. prof. V.V. Menshikova Moscow "Medicine" 1987
  • V. N. Ivanova, Yu. V. Pervushin and co-authors, “Methods for examining urine and the clinical and diagnostic significance of indicators of the composition and properties of urine,” Guidelines, Stavropol, 2005