Kidney tissue: The kidney remains a major part of the urinary system's function, to filter blood and create urine as a waste by-product.Credit: Ali Majdfar/Moment/Getty Images
A commonly used blood test to measure kidney function may not be effective for many people in Africa. A study, published in The Lancet Global Health, researchers found methods developed in wealthier locations could miss early signs of problems. The team, from the African Research on Kidney Disease (ARK) Consortium, conducted the study among 2500 participants from Malawi, South Africa and Uganda.
Kidney function is measured by determining how much creatinine or cystatin C is in a person’s blood. Creatinine is a by-product of muscle breakdown while cystatin C is a protein made by cells in the body. Healthy kidneys filter creatinine or cystatin C out of the blood and excrete these in urine. High levels of creatinine or cystatin C test can be a sign that the kidneys are not functioning properly.
To study the most accurate way to measure kidney function in African populations, the ARK Consortium compared the widely used creatinine and cystatin C-based tests with a benchmark test. (Called the iohexol measured glomerular filtration rate (mGFR).) The researchers found that creatinine-based tests were inaccurate for predicting kidney disease in African populations.
Laurie Tomlinson of the London School of Hygiene and Tropical Medicine, one of the authors says: “We have shown that for people living in Africa, differences in factors such as childhood health and current nutrition mean that if we’re using equations developed in the US and Europe, we may not be accurately estimating the kidney function of people globally.
“The burden of kidney disease in Africa has been substantially underestimated and kidney disease has not received the public health focus it requires,” says June Fabian, co-lead author of the study, from the University of the Witwatersrand, Johannesburg in South Africa. “We can’t assume it’s the same [for all people from Africa], especially given the extensive genetic biodiversity in Africa. We did see similar patterns of low creatinine in the blood in Malawi, Uganda and South Africa.”
A cystatin C test, which costs around US$ 19, would be much more suitable in Africa than than the widely used, but less accurate creatinine.
The changes do need to be implemented “as no science is life-saving if the results are not implemented, Fabian says.
“There is very little available treatment for treating kidney failure in Africa. If we can detect kidney disease early, using better tests, and intervene, we could prevent progression of early disease to kidney failure.”
