Race and GFR

What is GFR

volume of plasma filtered through the glomerulus per unit time
→ 100-120 ml/min is considered normal

How is GFR measured (3)

GFR is measured indirectly using a substance that is not reabsorbed or secreted but is fully filtered. Endogenous factors are favored over exogenous

1) inulin - an exogenous product but is tedious to measure over time

2) Creatinine
→ breakdown product of muscle and metabolism, so its generation is affected by muscle mass and diet
→ secreted in minute amounts so may affect GFR

3) Cystatin C
→ cysteine protease inhibitors and is inside nucleated cells
→ catabolized by the tubular epithelial cells, so less accurate

Why should race not be used to calculate GFR?

Race is flawed and a imprecise marker for serum creatinine levels
→ black patients were consistently estimated to have a higher GFR than they actually had, delaying treatment

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