Abstract
Recently, Schwartz et al. (J Am Soc Nephrol 20:629–637, 2009) used data from the National Institutes of Health-funded Chronic Kidney Disease in Children (CKiD) study to generate new equations for estimating the glomerular filtration rate (eGFR), including an update of the commonly used bedside equation. However, it is unclear if the equation can be generalized to a broader pediatric population. We have used the updated equation on a sample of pediatric patients with less impaired renal function to evaluate the correlation between the new Schwartz equation and measured GFR by iothalamate clearance. We retrospectively analyzed 738 iothalamate clearance tests from 503 patients with a mean serum creatinine of 0.50 mg/dl whose ages ranged from 1 to 16 years. We measured bias, precision, and accuracy and performed a Bland–Altman plot to determine the measure of agreement between the two methods. The mean GFR by iothalamate clearance was 110.6 ml/min/1.73 m2 and by the new Schwartz estimation 104.7 ml/min/1.73 m2. The mean difference was 5.84 ml/min/1.73 m2 (95% CI 4.00–7.67). The newly purposed bedside Schwartz equation therefore demonstrated good agreement with the iothalamate renal clearances in our patient population and appears to be a valid bedside estimating equation for GFR in this sample of children.
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Schwartz GJ, Haycock GB, Edelmann CM Jr, Spitzer A (1976) A simple estimate of glomerular filtration rate in children derived from body length and plasma creatinine. Pediatrics 58:259–263
Schwartz GJ, Furth S, Cole SR, Warady B, Munoz A (2006) Glomerular filtration rate via plasma iohexol disappearance: pilot study for chronic kidney disease in children. Kidney Int 69:2070–2077
Schwartz GJ, Munoz A, Schneider MF, Mak RH, Kaskel F, Warady BA, Furth SL (2009) New equations to estimate GFR in children with CKD. J Am Soc Nephrol 20:629–637
Pottel H, Mottaghy FM, Zaman Z, Martens F (2010) On the relationship between glomerular filtration rate and serum creatinine in children. Pediatr Nephrol 25:927–934
Brandt JR, Wong CS, Hanrahan JD, Qualls C, McAfee N, Watkins SL (2006) Estimating absolute glomerular filtration rate in children. Pediatr Nephrol 21:1865–1872
Kasiske BL, Keane WF (1996) Laboratory assessment of renal disease: clearance, urinalysis, and renal biopsy. In: Brenner B (ed) The kidney. WB Saunders, Philadelphia, p 1146
Brandt JR, Wong C, Jones DR, Qualls C, McAfee N, Brewer E, Watkins SL (2003) Glomerular filtration rate in children with solid tumors: normative values and a new method for estimation. Pediatr Hematol Oncol 20:309–318
Anderson CF, Sawyer TK, Cutler RE (1968) Iothalamate sodium I 125 vs cyanocobalamin Co 57 as a measure of glomerular filtration rate in man. JAMA 204:653–656
Elwood CM, Sigman EM (1967) The measurement of glomerular filtration rate and effective renal plasma flow in man by iothalamate 125-I and iodopyracet 131-I. Circulation 36:441–448
Cole BR, Giangiacomo J, Ingelfinger JR, Robson AM (1972) Measurement of renal function without urine collection. A critical evaluation of the constant-infusion technic for determination of inulin and para-aminohippurate. N Engl J Med 287:1109–1114
Holliday MA, Heilbron D, al-Uzri A, Hidayat J, Uauy R, Conley S, Reisch J, Hogg RJ (1993) Serial measurements of GFR in infants using the continuous iothalamate infusion technique. Southwest Pediatric Nephrology Study Group (SPNSG). Kidney Int 43:893–898
Weber AF, Lee DW, Opheim K, Smith AL (1985) Quantitation of iothalamate in serum and urine by high-performance liquid chromatography. J Chromatogr 337:434–440
Altman DG, Gore SM, Gardner MJ, Pocock SJ (1983) Statistical guidelines for contributors to medical journals. Br Med J (Clin Res Ed) 286:1489–1493
Harmon WE (2009) Glomerular filtration rate in children with chronic kidney disease. Clin Chem 55:400–401
Bland JM, Altman DG (1986) Statistical methods for assessing agreement between two methods of clinical measurement. Lancet 1:307–310
Schwartz GJ, Brion LP, Spitzer A (1987) The use of plasma creatinine concentration for estimating glomerular filtration rate in infants, children, and adolescents. Pediatr Clin North Am 34:571–590
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We would like to thank Rhona Jack, PhD at the Seattle Children’s Hospital Laboratory for her technical expertise for the revisions of this manuscript.
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Staples, A., LeBlond, R., Watkins, S. et al. Validation of the revised Schwartz estimating equation in a predominantly non-CKD population. Pediatr Nephrol 25, 2321–2326 (2010). https://doi.org/10.1007/s00467-010-1598-7
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DOI: https://doi.org/10.1007/s00467-010-1598-7