title: Comparison of different glomerular filtration methods in the elderly: which formula provides better estimates?
abstract: OBJECTIVE
  Technetium-99m diethylenetriaminepentaacetic acid ((99m)Tc-DTPA) is an ideal radioisotopic method having a high correlation with inulin clearance for the determination of glomerular filtration rate (GFR). Different formulas like creatinine clearance (CrCl) in 24 h urine samples, Cockroft-Gault formula (CGF), and modification of diet in renal disease (MDRD) are being used to come up with an estimate. In this study, we compared (99m)Tc-DTPA with the formulas mentioned above in an attempt to best identify the method that would yield the nearly ideal GFR estimates in the elderly.
  
  
  METHODS
  In 76 patients who were admitted to our clinic, we measured 24 h urine volume (V), urine creatinine (Ucr), and serum creatinine (Scr) levels together with CrCl, Scr, serum urea (Su), and albumin (Alb) levels. By using coefficients identified for age, gender, and race, we calculated modification of diet in renal disease 1 (MDRD1). Different from MDRD1, we calculated modification of diet in renal disease 2 (MDRD2) that does not include Su and Alb parameters and formulas like CGF that include Scr, age, gender, and weight parameters to come up with GFR levels. All patients underwent (99m)Tc-DTPA procedure.
  
  
  RESULTS
  The mean of the GFR values measured by (99m)Tc-DTPA was 54.3 ± 19.9. The means of GFR values calculated by CrCl, MDRD1, MDRD2, and CGF were 58.0 ± 30.5, 60.9 ± 22.1, 54.4 ± 20.1, and 57.9 ± 22.4, respectively. GFR as measured by (99m)Tc-DTPA showed statistically significant correlations with the results of other methods (p < 0.001 for all methods). The most significant correlation was with MDRD1.
  
  
  CONCLUSIONS
  MDRD1 can be used for next to ideal and accurate predictions of GFR in the elderly in the daily practice.
authors.affiliation: Department of Geriatric Medicine, School of Medicine, Ankara University, Ankara, Turkey. sevgidursun06@yahoo.com
authors.forename: Sevgi
authors.initials: S
authors.lastname: Aras
authors.forename: Murat
authors.initials: M
authors.lastname: Varli
authors.forename: Burcu
authors.initials: B
authors.lastname: Uzun
authors.forename: Teslime
authors.initials: T
authors.lastname: Atli
authors.forename: Kenan
authors.initials: K
authors.lastname: Keven
authors.forename: Murat
authors.initials: M
authors.lastname: Turgay
mesh_terms: D000367:Age Factors; D000368:Aged; D000375:Aging / Q000502:physiology*; D003404:Creatinine / Q000097:blood*; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate / Q000502:physiology*; D006801:Humans; D007668:Kidney / Q000502:physiology*; D007674:Kidney Diseases / Q000097:blood / Q000175:diagnosis / Q000503:physiopathology; D008297:Male; D008657:Metabolic Clearance Rate; D008962:Models, Theoretical; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D015203:Reproducibility of Results; D016284:Technetium Tc 99m Pentetate / Q000493:pharmacokinetics*
chemical_list: D019275:Radiopharmaceuticals; D003404:Creatinine; D016284:Technetium Tc 99m Pentetate