Introduction:
Glomerular filtration rate (GFR) is the most useful indicator of kidney function and kidney disease progression. Plasma creatinine based formulas to estimate GFR are recommended for regular clinical use in children by several clinical guidelines. The Schwartz formula was devised for this reason in the mid1970s in children but recent data suggested that this formula overestimates GFR. In 2009, Schwartz et al. adapted the classical Schwartz formula(cSchwartz) but used only one kcoefficient (k = 0.413) for all ages of children from infancy to adolescence. For that reason, in this study, we aimed to evaluate the reliability and applicability of the revised Schwartz formula(rSchwartz) in children with reflux nephropathy (RN).
Material and methods:
Our study included 154 patients with RN between 418 years of age who were followed up in our outpatient clinic. Glomerular filtration rate was calculated by using 24hour urine samples (24hr CCl), the cShwartz formula and rSchwartz formula for all patients.
Results:
Eighty nine patients (57.8%) were girl, 65 (42.2%) were boy and the mean age was 10,42±3,34 years. The mean 24hr CCl, GFR calculated with cShwartz formula and with rSchwartz formula were 144.97±40.39, 158.51±22.84 and 115.92±17.46 ml/min/1.73m2 respectively. Both Schwartz formulas showed good correlation with 24hr CCl (p<0.001) but the cShwartz formula was more correlated with 24hr CCl (r:0.414) than the rSchwartz formula (r:0.343).
Conclusions:
Herein we found that the cShwartz formula was more correlated with 24hr CCl than the rSchwartz formula. Revised Schwartz formula calculated by using only one kcoefficient is not reliable enough to estimate GFR in children including the period of infancy and adolescence. Further studies of children and adolescents are needed to evaluate the applicability of the rSchwartz formula.
