Creatinine Clearance Test

Creatinine Clearance is a test of glomerular filtration rate.
It is the volume of blood or plasma completely cleared of creatinine per unit time and expressed as milliliter per minute.
Creatinine clearance is mg of creatinine excreted per minute to mg of creatinine per ml of plasma.

To diagnose or monitor kidney disease, especially with comorbidities like nausea, oedema, etc.
To screen for kidney disease when there are risk factors like hypertension, diabetes, or family history of kidney disease
To adjust the dosage of medications
To evaluate the functions of a transplanted kidney

Urine is collected over 24-hour period and a blood sample is drawn.
Clearance from plasma is directly related to GFR which is –
Creatinine Clearance = GFR = (UV)/P
where U = Urinary Creatine in mg/dl, P = Plasma Creatinine in mg/dl and Volume of urine excreted in ml/min which is average 1400ml for 24-hour period.

Modified Procedure-
- Urine collected over 1 hour and volume recorded.
- Creatinine content in plasma and urine estimated.
- Creatine clearance calculated using above formula

Normal: 95-115 ml/min(male) and 85-110 ml/min(female)
Decreased Value(<75%) is strong indicator for decreased GFR which may be due to acute or chronic damage to glomerulus or any of its components.
Clearance value up to 75% of average normal value may indicate adequate renal function. In older people the clearance is decreased.
Useful for early detection of kidney function impairment before other clinical manifestations are seen.
Rise in plasma creatinine by 1mg leads to decrease in creatinine clearance by up to 50%