Often in case of health problems, doctors prescribe laboratory urine tests. There are many kinds of similar analyzes and each of them tells the doctor about the functionality of a particular organ. The general analysis is quite informative, clarifying the picture of the existing pathology. An important indicator in the study of urine is its relative density.
Relative density of urine
Relative density is considered to be the specific gravity of the biological fluid. This indicator is established on the basis of the level of concentration of its constituent components like urea, various salts, creatinine, uric acid, etc.
The urine specific gravity is determined by the volume of urine released by a person. If it is allocated a lot, the density indicators are low, and small volumes of urine will lead to a high specific gravity.
Specific gravity or density informs the doctor about the functionality of the kidney structures, and also how well the kidneys cope with the concentration activity. In fact, this indicator informs the specialist about the work of the kidneys. The relative density can vary according to the daily volume of the liquid consumed, the food consumed, etc.
Usually in the summer, the specific gravity is noticeably higher than in winter. In addition, the density increases significantly after eating meat or losing large amounts of fluid( hypertension, low fluid intake, diarrhea, unrestrained vomiting, etc.).Also, the specific gravity of urine is higher in men, while in children and women this figure is significantly lower.
How is it determined?
A standard urinalysis is performed to determine the urine specific gravity. If any abnormalities are found( hypostenuria or hypersthenuria), then additional studies like:
- Zimnitsky samples are assigned. The method involves the collection of urine throughout the day every 3 hours, i.e., only 8 servings. In healthy patients, the daily volume of urine is about 67-75% of the fluid drunk, with 65-75% excreted throughout the day. The specific weight of urine throughout the day can vary by 1,005-1,025 units. If the amplitude of the density index fluctuations is below or above the norm, then additional stress tests for dilution and urine concentration are shown.
- A sample for breeding. The essence of this urine test is as follows: the patient in the morning after urinating on an empty stomach drinks water( 20 ml per kg of body weight), and then empties after half an hour. And so several times. Samples are taken every 60 minutes for 4 hours. During the day, each urination is examined for a level of density. Normally, the specific weight should decrease to about 1,001-1,002, and when the load stops, the level rises to 1,008-1,030.If the indices do not decrease, then they speak of breeding disorders.
- Concentration test. The technique is that the patient does not drink anything for 24 hours and eats a protein-rich diet that promotes the production of urea. The patient collects every 4 hours a dose of urine, which is examined for a level of relative density. In healthy patients, this indicator after a daily deprivation of drinking is 1,028-1,030.If the maximum indicator of specific gravity in the course of such a study is 1.017, then they speak of a violation of concentration renal functions.
- Testing with the help of test strips FAN.The essence of the technique is the use of special indicator strips. In accordance with the color on the test strip, the specific gravity of urine is determined.
Deviation from the norm in the relative density of urine is observed if the specific gravity level is increased or decreased. Relative density increases with hypersthenuria, which is typical for pathologies like glomerulonephritis, pathological edema, diabetes, dehydration, nephrotic syndrome or toxicosis in pregnant women.
Decrease in specific gravity or hyposthenia develops against a background of renal insufficiency, diabetes insipidus, acute pyelonephritis or polyuria caused by copious drinking or taking diuretics.
Norm of urine density indices:
|2-3 year olds||1,010-1,017|
|4-12 year olds||1,012-1,020|
|Children 12 years and older, adults||1,010-1,022|
If some deviations from normal parameters were found during the study, the patient is referred for additional consultation with the endocrinologist or nephrologist.