Here’s a troubling reality: a blood test designed to check kidney function has been systematically telling doctors that Black patients’ kidneys are healthier than they actually are. For decades, kidney disease tests used a mathematical “race correction” that adjusted results based on whether a patient was Black or not. This seemingly technical decision had major consequences – patients were diagnosed later, treatment was delayed, and transplant waiting times were longer. At MRIKPA, we believe everyone deserves accurate diagnosis regardless of ethnicity. The good news is that the medical community is now fixing this problem, though the solution raises complex questions about how we design medical tests for diverse populations.
What is the kidney test problem?
The most common kidney function test measures creatinine (a waste product from muscles) in the blood to estimate how well kidneys filter. This estimated glomerular filtration rate (eGFR) is cheap, quick, and essential for detecting kidney disease early. However, in 1999, researchers noticed that Black Americans tend to have higher natural creatinine levels than white Americans. Rather than investigate why, they simply added a “race correction” to the equation – multiplying Black patients’ eGFR by 1.21, making their kidneys appear 21% healthier than the maths suggested. This tweak was intended to be accurate, but it had an unintended consequence: it delayed diagnosis and treatment for the very population with the highest rates of kidney disease.
You can read the full original article from Nature here: Making kidney tests work for everyone.
What fairer kidney testing could mean for patients
African Americans are affected by kidney disease at roughly four times the rate of Europeans Americans. For decades, the race-corrected eGFR equation meant that Black patients’ kidney disease went undetected for longer, transplant referrals came later, and waiting times were extended. In 2023, the US transplant system corrected these historical inequities, recalculating eGFR scores for Black patients on the waiting list. On average, this retroactive adjustment cut waiting times by two years – proof of how profoundly the biased test had affected real lives. The shift to a race-free equation aims to level the playing field so that all patients get diagnosed when they should be.
Progress, but not yet in every clinic
The US adopted a new, race-free kidney test equation in 2021, developed by pooling data from Black and non-Black patients. Other countries are taking different approaches – some European countries rejected the equation, whilst researchers in Africa are questioning whether creatinine-based tests work well for African populations at all (where malnutrition, lower muscle mass, and different disease patterns mean the test may be unreliable). There’s no global consensus yet, and that’s actually a sign of good science – acknowledging that one-size-fits-all medicine doesn’t work. An alternative biomarker called cystatin C doesn’t require race correction and works well across populations, but it costs three times more to measure. The real lesson is that good kidney testing requires both better science and willingness to examine how our biases get baked into medicine.
If you want to understand more about kidney testing and your own results, speak with your renal team. To learn more about kidney disease and patient care, visit our renal care pages and research updates.
If you have concerns about your kidney test results or would like to discuss your care, please contact your GP or renal team, or reach out to MRIKPA at support@mrikpa.org.uk or 07745 242 684.
Source: Drew, Liam. “Making kidney tests work for everyone.” Nature, December 12, 2024. https://www.nature.com/articles/d41586-024-04100-y
This article is provided for general information and awareness purposes only and was believed to be accurate at the time of publishing. It is not intended as medical advice – please always consult your doctor or renal team for guidance on your individual circumstances. Images used are for illustration purposes only and may not be medically or editorially accurate. While we take every care, errors can occur. If you spot an inaccuracy, please let us know at support@mrikpa.org.uk.
