title: GFR in Patients with β-Thalassemia Major.
abstract: OBJECTIVE
  Patients with β-thalassemia major (TM) may have tubular dysfunction and glomerular dysfunction, primarily hyperfiltration, based on eGFR. Assessment of GFR based on serum creatinine concentration may overestimate GFR in these patients. This study sought to determine GFR by using inulin clearance and compare it with measured creatinine clearance (Ccr) and eGFR.
  
  
  METHODS
  Patients followed up in an Israeli thalassemia clinic who had been regularly transfused for years and treated with deferasirox were included in the study. They were studied by inulin clearance, Ccr, the CKD Epidemiology Collaboration and the Modification of Diet in Renal Disease equations for eGFR, and the Cockcroft-Gault estimation for Ccr. Expected creatinine excretion rate and tubular creatinine secretion rate were calculated.
  
  
  RESULTS
  Nine white patients were studied. Results, given as medians, were as follows: serum creatinine was 0.59 mg/dl (below normal limits); GFR was low (76.6 ml/min per 1.73 m(2)) and reached the level of CKD; Ccr was 134.9 ml/min per 1.73 m(2), higher than the GFR because of a tubular creatinine secretion rate of 30.3 ml/min per 1.73 m(2) (this accounted for 40% of the Ccr); and eGFR calculated by the CKD Epidemiology Collaboration and Modification of Diet in Renal Disease equations and Cockcroft-Gault-estimated Ccr were 133, 141, and 168 ml/min per 1.73 m(2), respectively. These latter values were significantly higher than the GFR, reaching the hyperfiltration range, and indicated that the estimation techniques were clinically unacceptable as a method for measuring kidney function compared with the GFR according to Bland and Altman analyses.
  
  
  CONCLUSIONS
  Contrary to previous reports, patients in this study with TM had normal or reduced GFR. The estimating methods showed erroneous overestimation of GFR and were clinically unacceptable for GFR measurements in patients with TM by Bland and Altman analysis. Therefore, more accurate methods should be used for early detection of reduced GFR and prevention of its further decline toward CKD in these patients.
authors.affiliation: Department of Nephrology and Hypertension, Rabin Medical Center, Petah-Tikva, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and.
authors.forename: Gai
authors.initials: G
authors.lastname: Milo
authors.affiliation: Department of Nephrology and Hypertension, Rabin Medical Center, Petah-Tikva, Israel; Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and.
authors.forename: Revital
authors.initials: R
authors.lastname: Feige Gross Nevo
authors.affiliation: Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and Institute of Hematology, Rabin Medical Center, Petah-Tikva, Israel.
authors.forename: Idit
authors.initials: I
authors.lastname: Pazgal
authors.affiliation: Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and Institute of Hematology, Rabin Medical Center, Petah-Tikva, Israel.
authors.forename: Anat
authors.initials: A
authors.lastname: Gafter-Gvili
authors.affiliation: Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and Institute of Hematology, Rabin Medical Center, Petah-Tikva, Israel.
authors.forename: Ofer
authors.initials: O
authors.lastname: Shpilberg
authors.affiliation: Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and Institute of Hematology, Rabin Medical Center, Petah-Tikva, Israel gafter@post.tau.ac.il.
authors.forename: Uzi
authors.initials: U
authors.lastname: Gafter
authors.affiliation: Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and Institute of Hematology, Rabin Medical Center, Petah-Tikva, Israel.
authors.forename: Arie
authors.initials: A
authors.lastname: Erman
authors.affiliation: Sackler School of Medicine, Tel-Aviv University, Tel Aviv, Israel; and Institute of Hematology, Rabin Medical Center, Petah-Tikva, Israel.
authors.forename: Pinhas
authors.initials: P
authors.lastname: Stark
mesh_terms: D000328:Adult; D001565:Benzoates / Q000009:adverse effects*; D015415:Biomarkers / Q000097:blood; D003404:Creatinine / Q000097:blood; D000077588:Deferasirox; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects*; D006801:Humans; D007444:Inulin / Q000008:administration & dosage; D007502:Iron Chelating Agents / Q000009:adverse effects*; D007557:Israel; D007668:Kidney / Q000187:drug effects* / Q000503:physiopathology; D007674:Kidney Diseases / Q000097:blood / Q000175:diagnosis / Q000209:etiology* / Q000503:physiopathology; D008297:Male; D008954:Models, Biological; D010044:Outpatient Clinics, Hospital; D011237:Predictive Value of Tests; D015203:Reproducibility of Results; D065227:Transfusion Reaction; D014230:Triazoles / Q000009:adverse effects*; D055815:Young Adult; D017086:beta-Thalassemia / Q000175:diagnosis / Q000628:therapy*
chemical_list: D001565:Benzoates; D015415:Biomarkers; D007502:Iron Chelating Agents; D014230:Triazoles; D007444:Inulin; D003404:Creatinine; D000077588:Deferasirox
keywords: chronic kidney disease; glomerular filtration rate; glomerular hyperfiltration