Urine creatinine measurement, in combination with serum creatinine measurement, is used to calculate creatinine clearance, a measure of renal function.
Creatinine is the non-protein end product of anaerobic energy production from creatine phosphate metabolism in skeletal muscle. It is continuously and easily eliminated from the kidney by glomerular filtration. Decreased creatinine levels in the urine indicate a slowdown in glomerular filtration rate. Creatinine is therefore a very specific indicator of renal function. There is a daily variation in creatine levels that can be associated with meals, with the lowest observed around 07:00 in the morning and the highest observed around 19:00 in the evening. As this test involves the collection of a 24-hour urine sample, it results in a reduction in the impact on both high and low daily creatinine measurements.
Possible Interpretations of Pathological Values
- Increase: Fever, hypothyroidism, tissue catabolism. Medications that may cause falsely elevated urine creatinine values include: Amphotericin B, ascorbic acid, barbiturates, capreomycin sulfate, carbutamide, cefoxin, cephalothin, chlorothalidone, clonidine, phenolsulfonophthalein, sulfobromofthalin
- Decrease: Reduced renal hematopoiesis, glomerulonephritis, cystic kidney disease, polymyositis, pyelonephritis (chronic bilateral), cataplexy (hypokalemia). Medications that may cause faintly reduced urine creatinine values include: Anabolic steroids, androgens, thiazides
Laboratory test results are the most important parameter for the diagnosis and monitoring of all pathological conditions. 70%-80% of diagnostic decisions are based on laboratory tests. Correct interpretation of laboratory results allows a doctor to distinguish "healthy" from "diseased".
Laboratory test results should not be interpreted from the numerical result of a single analysis. Test results should be interpreted in relation to each individual case and family history, clinical findings and the results of other laboratory tests and information. Your personal physician should explain the importance of your test results.
At Diagnostiki Athinon we answer any questions you may have about the test you perform in our laboratory and we contact your doctor to get the best possible medical care.