Your kidneys are amazing organs. Each of your kidneys is about the size of the palm of your hand. And every day, approximately 40 gallons of blood get filtered through them every single day. That means they filter all of the blood in your body about ten times every twenty-four hours. The bad things get taken out by tiny filters called nephrons and sent to your bladder, while the rest keeps circulating. Kidneys are, not surprisingly, complex little systems. One problem with kidneys is that the nephrons do not regenerate if they are injured. So, diminished kidney function is not reversible. It turns out, though, that one of the common measurements for kidney function has baked in racist bias. Why does race keep appearing in our medical algorithms?
For decades the most common measure of kidney function, known as the estimate glomular filtration rate, or eGFR, has been adjusted to account for whether the patient is black. You can calculate your eGFR here. Fiddling with the numbers will show you just how different your eGFR is if you are black or not. You will notice that for the same creatinine value (measure of protein in your blood that the kidneys are NOT cleaning out), the calculator always estimates a higher eGFR for black patients, about 15% higher.
As a practical matter, that means that a provider relying on a race-differentiated eGFR would not recognize their patient’s kidney failure in a black patient until it is further along than a white patient.
Why is a social construct relied upon for this scientific calculation? The answer is not entirely clear, but it’s something akin to “it was an untested theory we developed in 1999 and everyone has just gone with it.” I mean, the entire theory is that Black Americans have a greater muscle mass than non-Black Americans. What amazed me even moreso was that this calculation was developed in 1999. Think about how this modifier matters for patients that identify as mixed-race? Or if the patient’s race is simply the provider’s guess? Race is, after all, merely a social construct.
Black Americans are more likely to suffer from kidney disease and have kidney failure than white americans. Reliance on algorithms with racial elements such as this may well contribute to this disparate outcome. And it is time to move away from racist bias in calculating kidney function.
