Renal Clearance
Start with the big picture
Clearance is the volume of plasma from which a substance is completely removed by the kidneys per unit time. It is calculated as C = (U × V) / P, using urine concentration, urine flow rate, and plasma concentration. Clearance equal to GFR indicates filtration without net reabsorption or secretion; a lower value suggests reabsorption, while a higher value suggests secretion. The lesson introduces inulin as a gold-standard marker for measuring GFR and creatinine as a clinically practical estimate that can slightly overestimate GFR because of tubular secretion. It also explains how plasma creatinine relates to GFR and how PAH clearance is used to estimate renal plasma flow.
What you'll learn
- Define renal clearance and identify the variables in its calculation.
- Interpret clearance values in relation to GFR.
- Compare inulin and creatinine as markers of GFR.
- Explain how PAH clearance estimates renal plasma flow.
- Identify clinical uses of renal clearance principles.
Continue your study
Work through the complete notes and reinforce the topic with the study tools available in the full lesson.
