['To assess the validity of two equations: K x 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) x weight/72 x creatinine (x0.85 for women; Cockroft-Gault) in estimating glomerular filtration rate in children and adolescents with IDDM.', "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, HbA1c, 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 < or = 140 ml.min-1 x 1.73 m-2, and patients with DTPA-GFR > 140 ml.min-1 x 1.73 m-2.", '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 x 1.73 m-2 (78-90). For patients with DTPA-GFR < or = 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 < or = 140 (r = 0.29), for Cockroft-Gault in all patients (r = -0.46), and for patients with DTPA-GFR < or = 140 (r = -0.31). Determination of a revised K for use in KL/Cr from individual calculations of K (DTPA-GFR x 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 < or = 140 ml.min-1 x 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).'] Do serum creatinine , height , and weight predict glomerular filtration rate in children with IDDM?