Serum Creatinine, Height, and Weight Do Not Predict Glomerular Filtration Rate in Children with IDDM

Wayne R Waz; Teresa Quattrin; Leonard G Feld

doi:10.2337/diacare.16.8.1067

Original Articles

Serum Creatinine, Height, and Weight Do Not Predict Glomerular Filtration Rate in Children with IDDM

Wayne R Waz, MD,
Teresa Quattrin, MD and
Leonard G Feld, MD, PHD

Department of Pediatrics, Divisions of Pediatric Nephrology and Pediatric Endocrinology, Children's Kidney and Diabetes Centers, The Children's Hospital of Buffalo Buffalo School of Medicine and Biomedical Sciences, The State University of New York at Buffalo Buffalo, New York

Address correspondence and reprint request to Leonard G. Feld, MD, PHD, Children's Kidney Center, Children's Hospital of Buffalo, 219 Bryant Street, Buffalo, NY 14222.

Diabetes Care 1993 Aug; 16(8): 1067-1070. https://doi.org/10.2337/diacare.16.8.1067

Abstract

OBJECTIVE To assess the validity of two equations: K × height/serum creatinine (KL/Cr; K = 0.55 for females 1–18 yr of age and 0.7 for males 12–18 yr of age) and (140 – age) × weight/72 × creatinine (×0.85 for women; Cockroft-Gault) in estimating glomerular filtration rate in children and adolescents with IDDM.

RESEARCH DESIGN AND METHODS From the records of the Children's Hospital Diabetes Clinic, we selected 70 patients with GFR determined by ^99mTc-labeled DTPA plasma clearance, stable renal function, and simultaneous measurements of height, weight, blood pressure, HbA_1c, and plasma creatinine. We compared DTPA-GFR with estimated GFR from KL/Cr and Cockroft-Gault equations for three groups: all patients, patients with DTPA-GFR ≤ 140 ml·min⁻¹ · 1.73 m⁻², and patients with DTPA-GFR > 140 ml·min⁻¹ · 1.73 m⁻².

RESULTS For all patients, mean values for DTPA-GFR = 147 (95% confidence interval, 139–155), for KL/Cr = 118 (110–125), and for Cockroft-Gault = 84 ml–·min⁻¹ · 1.73 m⁻² (78–90). For patients with DTPA-GFR ≤ 140, DTPA-GFR = 123 (117–128), KL/Cr = 110 (100–119), and Cockroft-Gault = 92 (82–102). For patients with DTPA-GFR > 140, DTPA-GFR = 167 (158–177), KL/Cr = 125 (114–136), and Cockroft-Gault = 77 (71–84). Linear regression analysis showed significant (P < 0.05) relationships for KL/Cr only in patients with DTPA-GFR ≤ 140 (r = 0.29), for Cockroft-Gault in all patients (r = −0.46), and for patients with DTPA-GFR ≤ 140 (r = −0.31). Determination of a revised K for use in KL/Cr from individual calculations of K (DTPA-GFR × Cr/L) yielded an average value of 0.70 (SD = 0.11). With the use of K = 0.7, the mean KL/Cr value for patients with DTPA-GFR ≤ 140 ml·min⁻¹ · 1.73 m⁻² was 125 ± 27 (95% confidence interval, 115–135), compared with a DTPA-GFR value of 123 ± 14 (95% confidence interval, 117–128).

CONCLUSIONS KL/Cr and Cockroft-Gault do not accurately estimate DTPA plasma clearance. We recommend the use of K equal to 0.70 when estimating GFR in children and adolescents with IDDM and DTPA-GFR ≤ 140 using KL/Cr and do not recommend the use of the KL/Cr (for patients with DTPA-GFR > 140) or the Cockroft-Gault equation in this population.