NEW YORK (Reuters Health) – US researchers have developed a clinical equation that may enhance the estimation of glomerular filtration rate (GFR) in children with chronic kidney disease, according to the report in the March issue of the Journal of the American Society of Nephrology.

“This new precise tool should help pediatricians accurately and easily gauge their patients’ kidney function and predict a patient’s ability to sustain any potentially dangerous treatments that could harm the kidneys,” study co-author Dr. Susan L. Furth, from Johns Hopkins Children’s Center, said in a statement.

In the mid-1970s, Dr. George J. Schwartz, the lead author of the present study, and colleagues devised a method for estimating GFR in children. Although widely used, recent evidence suggests that the formula, which relies on serum creatinine, height, and an empirical constant, may overestimate the GFR as measured with tests based on the plasma disappearance of iohexol.

Dr. Schwartz, from the University of Rochester Medical Center, New York, and colleagues believe that this overestimation may result from changes in how serum creatinine is measured.

In the present study, the research team examined a number of clinical parameters to create a formula that would provide a more accurate reflection of the iohexol-GFR. The study group included 349 children from the Chronic Kidney Disease in Children cohort who had a median iohexol-GFR of 41.3 mL/min per 1.73 m² and a median creatinine level of 1.3 mg/dL.

The formula that generated the most accurate GFR estimate included height, serum creatinine, cystatin C, blood urea nitrogen, and gender. “This formula,” the authors note, “yielded 87.7% of estimated GFR within 30% of the iohexol-GFR, and 45.6% within 10%.”

“Further study of children and adolescents with more normal kidney function will enhance the use of the formulas for use with most children and particularly those with mild chronic kidney disease,” the authors state.

Reference:
J Am Soc Nephrol 2009.