Final answer:
The creatinine clearance test measures the glomerular filtration rate (GFR) to assess kidney function. The results help in adjusting medication dosages excreted via the kidneys and are adjusted for body surface area. Normal values vary based on age, gender, and the presence of factors affecting urine flow.
Step-by-step explanation:
The creatinine clearance test is a measure of the glomerular filtration rate (GFR), which indicates how well the kidneys are filtering waste from the bloodstream. GFR is assessed to ensure safe medication dosing and to check for kidney function decline. A creatinine clearance test uses the formula Ccr = (U x V) / B, where 'U' is the concentration of creatinine in urine, 'V' is the urine flow rate, and 'B' is the concentration of creatinine in blood plasma. This test often requires a 24-hour urine collection and may be adjusted for body surface area (BSA) to normalize values across different individual body sizes, typically reported as milliliters per minute per 1.73 m². Normal values for the creatinine clearance vary by age and gender.
Factors that can affect the creatinine clearance test results include medications that interfere with bladder emptying, prostate conditions, kidney stones, and obstruction of the urinary tract. The GFR estimated by the creatinine clearance is crucial for dosage adjustments in medications that are primarily excreted by the kidneys to prevent toxic accumulations.
For individuals with suspected renal impairment, the creatinine clearance test is a valuable diagnostic tool alongside other blood tests to assess renal function, such as blood urea nitrogen (BUN) and serum creatinine levels.