Urinalysis by Zimnitsky - Causes, symptoms and treatment. MF.

Study of osmoregulatory function of the kidneys

The main function of the kidneys is purifying, by selectively removing from the blood excess substances for the body and delay necessary, which ensures the maintenance of constancy of the blood composition. The simplest functional test is based on determining the impairment of the kidney's ability to concentrate and dilute the urine.

The study is based on the ability of the kidneys to osmotically concentrate and dilute the urine. These processes depend on the effective work of nephrons, general hemodynamics, determining the rheology of blood, renal blood flow, neurohumoral regulation and other factors. Violation of any link leads to a change in kidney function.

Urine in Zimnitskiy: preparation for

analysis Urine test for Zimnitsky is prescribed when there is a suspicion that the patient develops kidney failure or inflammation of the kidneys.

Collecting urine for analysis in Zimnitskiy is not an easy task. This requires a whole day and six cans. Each - for urine, allocated for every four hours during the day. When the urine is collected, the quantity and specific gravity are determined in each portion. Calculations are complex, but it is important that the amount of urine released by the day is greater than the "night" quantity and that the specific weight of all portions fluctuates in a certain way - 1010-1012.

Zimnitsky's sample

Zimnitsky's assay is based on a study of the relative density in individual portions of urine released during an arbitrary urination during a day at a certain rhythm. The study is carried out under normal nutritional conditions without liquid restriction.

Urine is collected every three hours during the day and its amount, relative density, and also the amount of sodium chloride and urea are examined. The content of chlorides and urea is determined in the day and night portions of urine. The total amount of urine released during the day is 65-75% of the fluid.

The normal response of the kidneys is judged by the following indices:

• excess daily diuresis over night
• the greatest fluctuation in the amount and relative density of urine from 1.004 to 1.032 in its individual portions
• the difference between the highest and lowest relative density, which should not be less than 0,007
• sharpincreased urination after intake of
• fluid by excretion of at least 80% of the injected fluid by the kidneys

About pathology testify:

• monotony of urination
• excess of nocturnal diuresisd day
• small amplitude oscillations relative density( 1,007- 1,009 -1.010 -1,012)
• polyuria
  
  methods based on the study of the purification of the kidney( clearance) are considered the most reliable.

By renal clearance is the amount of blood serum( in ml), which is purified completely per unit time from any exogenous or endogenous substance. There are the following types of clearance:

1. Filtration clearance, when the substance is released as a result of filtration and not reabsorbed in the tubules. This clearance has creatinine. It determines the value of glomerular filtration.
2. Excretory clearance, when the substance is excreted by filtration and tubular excretion, without reabsorption. This clearance determines the amount of plasma transmitted through the kidney. Such a substance is a diode.
3. Reabsorption clearance, in which the substance is released by filtration and completely reabsorbed in the tubules. Such substances include glucose, protein. Their clearance is 0. At high concentrations of the substance in the blood, the clearance determines the maximum ability of the tubules to reabsorb.
4. Mixed clearance is observed with the ability of the filter substance to partial reabsorption. Urea has such a clearance.

The clearance of the detectable substance corresponds to the difference between the content of this substance in the urine and in the plasma in 1 min. Calculate the clearance( C) according to the formula:

C =( U x V): P

where C is the clearance of the substance in ml / min
U is the concentration of the test substance in urine in mg / ml
V is diuresis in ml / min
P - concentration of test substance in plasma in mg / ml

Clearance depends on age, so it is different in children and adults, and on the degree of kidney damage.

Most often, creatinine and urea are used to detect renal dysfunction( functional capacity of the glomeruli and tubules), as well as for the differential diagnosis of nephropathies.

Increased concentration in the blood of creatinine and urea, concomitant with renal dysfunction is a sign that pathognomonic kidney failure, but the concentration of creatinine in the blood rises earlier than urea. Determining it to identify kidney dysfunction is more revealing.