Creatinine in urine
Last reviewed: 23.04.2024
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Daily excretion of creatinine with urine is relatively constant, is equivalent to daily production and directly depends on the mass of muscles and excretory capacity of the kidneys. With an animal-rich diet, the release of creatinine increases with urine.
Reference values (norm) of creatinine in the urine
|
Creatinine in the urine | ||
|
Age |
Mg / (kg x day) |
μmol / (kg × day) |
|
Children under 1 year old |
8-20 |
71-177 |
|
Children from 1 year to 12 years |
8-22 |
71-194 |
|
Teens |
8-30 |
71-265 |
|
Adults: | ||
|
Men's |
14-26 |
124-230 |
|
Women |
11-20 |
97-177 |
|
Or |
Mg / day |
Mmol / day |
|
Men's |
800-2000 |
7.1-17.7 |
|
Women |
600-1800 |
5.3-15.9 |
Parallel determination of the concentration of creatinine in blood and urine greatly expands the diagnostic possibilities of assessing the functional state of the kidneys.
In clinical practice, it is important to determine the ratio of creatinine in the urine to plasma creatinine. It is practically important to distinguish prerenal acute renal failure from renal insufficiency, especially in principle to establish the moment of transition of one form of acute renal failure to another, as this determines the change in the tactics of treating the patient.
Prerenal (functional) acute renal failure develops due to a decrease in the volume of circulating blood, severe heart failure, arterial hypotension, liver failure. Renal acute renal failure is caused by processes involving damage to the glomerular and tubular apparatus of the kidneys, kidney vascular disease.
With prerenal acute renal failure, the kidneys to reduce perfusion respond with enhanced sodium and water retention. Reabsorption of water by the kidneys is estimated by the concentration of unreabsorbed creatinine in urine, in the form of a ratio (urine creatinine) / (plasma creatinine). In prerenal acute renal failure this ratio is above 40, whereas in renal acute renal insufficiency, the ability to keep water is impaired, so it is less than 20. The decrease in the ratio (urine creatinine) / (plasma creatinine) with prerenal acute renal failure indicates a transition to a renal form and serves as a justification for changing therapy. Acute obstruction of the urinary tract leads to changes in the ratio (urine creatinine) / (plasma creatinine), characteristic of prerenal acute renal failure.
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