Creatinine Clearance, Serum and 24 Hrs Urine

Determination of creatinine in both serum and urine to estimate glomerular filtration rate (GFR) of endogenous creatinine is the most common procedure for assessing renal function. Because increased concentrations of creatinine in serum are usually not observed until over half of glomerular function is lost, calculation of creatinine clearance provides a more nearly-accurate assessment of the GFR. However, because of tubular creatinine secretion, the creatinine clearance overestimates the GFR. GFR is best determined under standardised conditions, which include discontinuation of medication, priorfasting, supine posture, sufficient water loading to maintain a urine flow rate of > 1 mL/min, and complete bladder emptying.

Determination of creatinine clearance may more sensitively indicate renal impairment than serum creatinine levels. A creatinine clearance value that is 20 to 40% of normal indicates severe renal disease, values between 40 to 60% of normal suggest moderate impairment, and values between 60 to 80% of normal reflect mild dysfunction. Because overall drug-elimination rate constants and creatinine clearance are linearly related, one can use creatinine clearance to adjust drug dosage in patients with renal disease. In addition, clearance ratios of creatinine and specific metabolites have their diagnostic utility.

1 ml Serum and 5 ml of 24 Hrs Urine Collection For sample stability refer to Creatinine, Serum/Plasma and Creatinine, 24 Hrs Urine

Avoid tea, coffee, and drugs during specimen collection. State 24 Hrs urine volume.

71-151 mL/min