Simple Test of Kidney Function Needs More Consideration

Kidney disease in the USA and other parts of the world is both common and under-diagnosed, but new studies suggest that paying close attention to results of a simple blood test can help predict the likelihood that patients will develop kidney failure.

A single determination of estimated glomerular filtration rate (eGFR) associates with subsequent mortality risk and prior decline in eGFR indicates loss of kidney function, but the relationship to mortality risk is uncertain. The eGFR is usually based on serum creatinine level, age, sex, and race. The most widely used method for this is the abbreviated MDRD equation, as it has proved the most robust and accurate.

A large team of scientists led by those at Johns Hopkins Bloomberg School of Public Health (Baltimore, MD, USA) analyzed data on more than 1.2 million subjects with and without kidney disease, more than 102,000 of whom died over a three-year study period. They primarily focused on the results of tests of the eGFR, which is used to screen for and detect early kidney damage and to monitor kidney function. They looked at the most recent eGFR but also at test results over time in the same patients.

The investigators found that the most recent eGFR value was the most valuable when it came to predicting both kidney failure and mortality, looking at historical tests also provided information that could be useful to patients and physicians. Electronic medical records routinely found in many hospitals and physicians' offices should be useful in determining the trajectory of kidney function over time. Having this information not only informs prognosis, but can help doctors steer their patients toward treatments such as ACE inhibitors which can slow the decline in kidney function among patients with protein in their urine or away from non-steroidal anti-inflammatory drugs (NSAIDS) such as ibuprofen which can damage the kidneys.

Josef Coresh, MD, a Professor of Epidemiology and coauthor of the study said, “Patients and physicians should pay attention to the estimates of kidney function which are routinely obtained, but all-too-often ignored. It costs little to do this test and it is done all the time. The results can inform treatment decisions that may be able to slow kidney function decline. While the test is more informative to doctors than a glucose test for diabetes, the results are many times overlooked, particularly when a patient has other chronic illnesses that required more immediate consideration.” The study was published on December 11, 2015, in the Journal of the American Society of Nephrology.

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Johns Hopkins Bloomberg School of Public Health