Examinations
Examinations
The Zimnitsky test is used to assess the kidneys’ ability to concentrate and excrete urine.
To obtain accurate results, patients should avoid excessive fluid intake during the test period.
Urine is collected in 8 separate containers, every 3 hours over a 24-hour period.
Each sample is measured for volume and specific gravity (urine density).
Advantages of the Zimnitsky Test
Determines total daily urine output (diuresis) and identifies polyuria or oliguria
Separates daytime and nighttime urine volumes, allowing for the detection of nocturia
Tracks fluctuations in specific gravity throughout the day, including peak values
Starting at 6:00 AM, the patient collects all urine passed every 3 hours into separate containers
The eighth sample is collected the next day at 6:00 AM
All containers must be clearly labeled with time and kept in a cool place until they are delivered to the lab
Detection of polyuria or oliguria – assessing whether total daily urine output is abnormally high (polyuria) or low (oliguria)
Assessment of daytime and nighttime diuresis – comparing urine volume during the day and at night to identify possible nocturia
Normal reference values:
Total daily urine output: 1000–2000 mL
Volume per portion: 50–250 mL
Daytime diuresis should exceed nighttime diuresis
Specific gravity should fluctuate between 1.010 and 1.025
If the maximum specific gravity in any sample exceeds 1.020, the kidneys’ concentrating ability is considered normal