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
• 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

(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
• 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

More general terms

• chemistry panel
• renal function tests; renal function panel

Component of

• renal function tests; renal function panel
• electrolyte/fluid management panel
• creatinine & glomerular filtration rate panel

Components

• creatinine in serum/plasma
• creatinine in 24 hour urine

Patient information

creatinine clearance patient information