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creatinine clearance
Indications:
- evaluation of renal disease
Principle:
- the creatinine clearance is determined by a 24 hour urine for creatinine along with serum creatinine according to the following equation:
Creatinine (urine) (mg/dL) x volume (mL) / Creatinine (serum) (mg/dL) x minutes
- the creatinine clearance is often estimated using a patient's age, weight & sex according to the Cockcroft-Gault equation.
(140 - age) x weight* (kg) / 72 x creatinine (serum) (mg/dL)
x 0.85 for women
* ideal body weight
- overestimates GFR by 10-20% because of tubular secretion of creatinine [2]
- use of cimetidine (400 mg PO TID or 800 mg QHS) suppresses the tubular secretion of creatinine, thus giving a better estimate of the true creatinine clearance
Decreases:
- renal insufficiency
- renal failure
Notes:
- collection of 24 hour urine problematic
- useful in pregnancy, young & old age, obesity or cachexia, amputees, cirrhosis [2]
General
chemistry panel
renal function tests; renal function panel
References
- Manual of Medical Therapeutics, 28th ed, Ewald &
McKenzie (eds), Little, Brown & Co, Boston, 1995, pg 262
- Medical Knowledge Self Assessment Program (MKSAP) 11, 17.
American College of Physicians, Philadelphia 1998, 2015
- Panel of 6 tests
Laboratory Test Directory ARUP: 20474
Component-of
creatinine & glomerular filtration rate panel
electrolyte/fluid management panel
renal function tests; renal function panel
Components
creatinine in 24 hour urine
creatinine in serum/plasma