title: Glomerular hyperfiltration and proteinuria in transfusion-independent patients with β-thalassemia intermedia.
abstract: Renal manifestations have been described in β-thalassemia major and were attributed to transfusional iron overload and chelation therapy. Patients with the milder phenotype, β-thalassemia intermedia (TI), remain largely transfusion and iron chelation independent while enduring a chronic hemolytic anemia and primary iron overload. Data on renal function in patients with TI is lacking.
  
  
  
  In this cross-sectional study of 50 TI patients, we evaluated the association of estimated glomerular filtration rate (eGFR) and urinary protein to creatinine (UPr/UCr) ratio with relevant patient, disease and laboratory indices.
  
  
  
  The median age of patients was 28 years (44% males). The eGFR was >90 ml/min/1.73 m(2) in all patients, with a median value of 142.3 ml/min/1.73 m(2). The median UPr/UCr ratio was 213.2 mg/g. There was a negative correlation between age and eGFR, while the UPr/UCr ratio correlated positively with markers of anemia, hemolysis and iron overload. A total of 24 (48%) patients had evidence of glomerular hyperfiltration, while 7 (14%) had proteinuria (UPr/UCr ratio >500 mg/g). Patients with proteinuria were characterized by elevated liver iron concentration (>7 mg Fe/g dry weight), non-transferrin-bound iron levels and nucleated red blood cell counts.
  
  
  
  A considerable proportion of TI patients show evidence of abnormally elevated eGFR, with a declining trend towards advancing age. The occurrence of proteinuria is associated with anemia, hemolysis and iron toxicity.
authors.affiliation: Department of Internal Medicine, American University of Beirut, Beirut, Lebanon.
authors.forename: Fuad N
authors.initials: FN
authors.lastname: Ziyadeh
authors.forename: Khaled M
authors.initials: KM
authors.lastname: Musallam
authors.forename: Naji S
authors.initials: NS
authors.lastname: Mallat
authors.forename: Samir
authors.initials: S
authors.lastname: Mallat
authors.forename: Fadel
authors.initials: F
authors.lastname: Jaber
authors.forename: Ali Abdulnabi
authors.initials: AA
authors.lastname: Suwaidan
authors.forename: Suzanne
authors.initials: S
authors.lastname: Koussa
authors.forename: Ali T
authors.initials: AT
authors.lastname: Taher
mesh_terms: D000293:Adolescent; D000328:Adult; D015897:Comorbidity; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate; D006801:Humans; D019190:Iron Overload / Q000097:blood / Q000453:epidemiology*; D007674:Kidney Diseases / Q000175:diagnosis* / Q000453:epidemiology*; D007861:Lebanon / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011507:Proteinuria / Q000097:blood / Q000453:epidemiology*; D018570:Risk Assessment; D055815:Young Adult; D017086:beta-Thalassemia / Q000175:diagnosis / Q000453:epidemiology*