Medical Laboratory Scientist (MLS) ASCP Practice Exam

The glomerular filtration rate (GFR) is a crucial measure of kidney function, indicating how well the kidneys are filtering waste from the blood. One of the most commonly utilized methods to estimate GFR in clinical practice is through creatinine clearance.

Creatinine, a waste product generated from muscle metabolism, is produced at a relatively constant rate and is predominantly filtered out by the kidneys. Measuring creatinine levels in both serum and urine allows clinicians to estimate how effectively the kidneys are filtering this substance. The formula for creatinine clearance involves the concentration of creatinine in urine, the volume of urine produced over a specified time, and the serum creatinine concentration.

While inulin clearance is considered a gold standard for measuring GFR due to its properties of being entirely filtered by the kidneys without reabsorption or secretion, it is less commonly used in routine clinical practice because it requires special techniques and conditions for accurate measurement. Urea clearance and albumin clearance are generally less effective indicators of kidney function compared to creatinine clearance and are not typically used to estimate GFR.

Thus, creatinine clearance stands out as the practical and widely accepted method for calculating glomerular filtration rate in most clinical settings.