Assessment of glomerular filtration rate in infants. Comparison of three methods used in clinical practice.
Glomerular filtration rate was assessed in 66 infants less than 1 year of age. Results obtained by 3 different routine methods were compared to those obtained by the standard inulin clearance (GFR): 1. clearance values calculated from plasma creatinine concentration (mg/dl) and height (cm), using a k value of 0.55 derived from inulin clearance did not reliably reflect GFR (Y = 37.5 + 0.51 Cin, r = 0.82); 2. creatinine clearance values calculated over 3 h overestimated standard inulin clearance at all levels of GFR below 100 ml/min.1.73m2 (Y = 25.1 + 0.75 Cin, r = 0.77). 3. Clearance values calculated as the sum of twice the creatinine clearance plus the urea clearance, divided by 3, overestimated the standard inulin clearance at low levels of GFR and underestimated it at high GFR (Y = 20.6 + 0.66 Cin, r = 0.82). The study of several techniques for estimating GFR in infants demonstrates that there is no ideal substitute for the traditional inulin clearance when precise measurement of glomerular filtration rate is needed, and that simple 3 h creatinine clearances represent a satisfactory and rational estimate of GFR in clinical practice.
Alinei
P
P
Department of Pediatrics, Centre Hospitalier Universitaire Vaudois, Lausanne, Switzerland.
Guignard
J P
JP
D000367:Age Factors; D001827:Body Height; D003404:Creatinine / Q000097:blood / Q000652:urine; D005919:Glomerular Filtration Rate / Q000379:methods*; D006801:Humans; D007223:Infant; D007231:Infant, Newborn; D007444:Inulin / Q000652:urine; D008954:Models, Biological; D012015:Reference Standards; D014508:Urea / Q000652:urine
D014508:Urea; D007444:Inulin; D003404:Creatinine