A better way to measure kidney function

Analysis forecasts effects of new race-free kidney-function testing

Illustration of kidneys inside a skeletal frame
Image: Mohammed Haneefa Nizamudeen/iStock / Getty Images Plus

Race — a social construct — is highly unreliable as a predictor of biologic variation across populations. Mounting evidence showing that race is not biology has called into question the use of many diagnostic tests and treatment approaches that still rely on outdated notions of race as a way to capture differences in biology and physiologic function across individuals with different genetic ancestries.

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Recently, a task force convened by the National Kidney Foundation and the American Society of Nephrology recommended a new race-free clinical calculator to estimate how well a person’s kidneys work. For decades, the formula to calculate kidney function has included race as one of several variables.

The task force has recommended three race-free equations, each one including different combinations of variables, including as a patient’s age and sex plus levels of creatinine (a waste by-product filtered by the kidneys) and cystatin-C (a protein released by cells and broken down by the kidneys).

But what will the adoption of these new formulas mean in practical terms for patients and for the clinicians who treat them?

This is the question that for several years has occupied the attention of a research team led by investigators at Harvard Medical School. The team’s latest report, published Nov. 11 in the Journal of the American Society of Nephrology, caps a series of studies and represents the most comprehensive analysis yet on the effects of new calculators for kidney-function assessment.