Experts are saying the results for African-American patients may not be accurate, and that could result in incorrect or delayed treatment.
Seven years ago, 64-year-old Bruce Elliot Ray lost one kidney to cancer, so tracking his kidney function is crucial.
"When you have one kidney, the other kidney has to work harder," Ray says.
One test doctors have relied on for decades has drawn a lot of scrutiny because it overestimates kidney function in Black patients, masking the severity of the disease.
"My first thought is did I get misdiagnosed?"
The eGFR test is the most widely-used formula to calculate kidney function. It measures creatinine, a waste product of muscles, and factors in age, sex, weight - and race.
"When you're putting in the African American or Black factor in there then you're getting two numbers," says nephrologist Dr. Pascal Dabel with Providence Holy Cross. "You would tell that individual 'Oh you're African American so your kidney function is 29% - not 25%."
Dabel says the difference can impede treatment and push African Americans further down the line for a kidney transplant.
"It's probably a lot of delay in care and it's probably tens of thousands of patients."
But why give African Americans two different test results?
Doctors just don't have a good answer for that.
"It's really hard to say but the good thing is that now this has been caught," Dabel says. "And it has been acknowledged by a lot of individuals in the medical world."
Starting this year, the Organ Procurement and Transplantation Network board has prohibited the use of the Black race variable and is asking doctors to identify and notify African Americans who should have been put on the transplant list sooner.
Dr. Dabel's advice? Ask a lot of questions and don't be afraid to get a second opinion.
"You have take good care of yourself and not let an equation or some other factor delay you getting the care that you need," Dabel says.
Ray hopes to raise awareness so patients can get the most accurate information possible.
"I'm glad we're doing it so we can move forward and at least get the right diagnoses that we need," Ray says.