Measuring kidney function in children can be expensive, time-consuming for clinicians, and tedious for children, who may be exposed to radioactivity and subjected to a large number of blood draws.
A new calculation eliminates many of these obstacles, relying instead on various blood tests that can be performed in a clinical setting to offer an accurate estimate of a child's kidney function.
This new estimate formula, developed from a study that will appear in the Journal of the American Society of Nephrology in March, could prove a valuable tool for adjusting fluids, antibiotics and chemotherapy and more accurately assessing kidney function in children battling chronic kidney disease (CKD). This formula can be used to estimate glomerular filtration rate (GFR) - the rate at which fluid is filtered through the kidneys - quickly and without infusing any synthetic substances. It was developed from a multi-site NIH-funded study for which the University of Rochester serves as the central biochemistry laboratory.
"Most other formulas used to estimate kidney function in children with CKD are singular to their institutions or hospitals. In addition, most clinicians are unaware of what biochemical analyses are being used by their institutions to measure waste products excreted by the kidney, such as creatinine and blood urea nitrogen (BUN), and different analyses would yield different estimate formulas," said George J. Schwartz, M.D., chief of Pediatric Nephrology at the University of Rochester Medical Center's Golisano Children's Hospital at Strong and director of University of Rochester's biochemistry lab. "An accurate estimate is crucial to properly treat children with acute and chronic kidney problems and the scale of this study makes its findings quite significant."
The study included 349 patients from more than 50 institutions across North America and was based on data collected by the CKiD Study, which was funded by the National Institute of Diabetes and Digestive and Kidney Diseases, part of the National Institutes of Health. Schwartz is a principal investigator in the Chronic Kidney Disease in Children (CKiD) Cohort Study.
The new GFR formula generated by the study is based on height and gender, serum creatinine and BUN, and cystatin C - a ubiquitous protein that is well-correlated with kidney function. These factors can be quickly and easily measured in a clinical setting without the need for radioactivity or urine collection.