title: Long-term treatment with tenofovir in Asian-American chronic hepatitis B patients is associated with abnormal renal phosphate handling.
abstract: BACKGROUND
  Increased risk of defective urinary phosphate reabsorption and osteoporosis has been reported in HIV and chronic hepatitis B (CHB) patients treated with tenofovir disoproxil fumarate (TDF).
  
  
  OBJECTIVE
  Goals of this study were to evaluate the prevalence of renal phosphate wasting and abnormal bone mineral density in CHB patients taking TDF compared to CHB patients treated with entecavir (ETV) and untreated CHB patients.
  
  
  METHODS
  This is a cross-sectional study of 146 consecutive Asian-American CHB patients who were treatment naïve (n = 60) or treated with either TDF (n = 42) or ETV (n = 44). Proximal tubular handling of phosphate was assessed by the maximal rate of tubular reabsorption of phosphate (TmPO4) divided by glomerular filtration rate (GFR) (TmPO4/GFR). Bone mineral density (BMD) was measured using dual X-ray absorptiometry.
  
  
  RESULTS
  TmPO4/GFR was similar among CHB patients treated with TDF compared to untreated patients and patients taking ETV. However, among patients treated with ≥18 months of TDF or ETV, prevalence of abnormal TmPO4/GFR was higher among patients treated with TDF compared to ETV (48.5 % (16/33) vs. 12.5 % (3/24), p = 0.005). Overall prevalence of osteoporosis in this cohort of CHB patients was 14 %, with no significant difference between the three groups. Renal phosphate handling did not correlate with osteoporosis.
  
  
  CONCLUSIONS
  Chronic hepatitis B patients treated with ≥18 months of TDF experienced an increased risk of proximal tubular dysfunction. TDF did not increase the risk of osteoporosis. Longitudinal studies are needed to confirm these findings.
authors.affiliation: Asian Pacific Liver Center, Saint Vincent Medical Center, Los Angeles, CA, USA.
authors.forename: Connie
authors.initials: C
authors.lastname: Tien
authors.forename: Jason J
authors.initials: JJ
authors.lastname: Xu
authors.forename: Linda S
authors.initials: LS
authors.lastname: Chan
authors.forename: Mimi
authors.initials: M
authors.lastname: Chang
authors.forename: Carolina
authors.initials: C
authors.lastname: Lim
authors.forename: Sue
authors.initials: S
authors.lastname: Lee
authors.forename: Brian
authors.initials: B
authors.lastname: Huh
authors.forename: Shuntaro
authors.initials: S
authors.lastname: Shinada
authors.forename: Ho S
authors.initials: HS
authors.lastname: Bae
authors.forename: Tse-Ling
authors.initials: TL
authors.lastname: Fong
mesh_terms: D015502:Absorptiometry, Photon; D000225:Adenine / Q000009:adverse effects / Q000031:analogs & derivatives*; D000328:Adult; D000368:Aged; D000998:Antiviral Agents / Q000009:adverse effects*; D044466:Asian People; D015519:Bone Density / Q000187:drug effects; D003430:Cross-Sectional Studies; D005260:Female; D005919:Glomerular Filtration Rate / Q000187:drug effects; D019694:Hepatitis B, Chronic / Q000175:diagnosis / Q000188:drug therapy* / Q000208:ethnology; D006801:Humans; D007687:Kidney Tubules, Proximal / Q000187:drug effects* / Q000378:metabolism / Q000503:physiopathology; D008297:Male; D008875:Middle Aged; D063065:Organophosphonates / Q000009:adverse effects*; D010024:Osteoporosis / Q000139:chemically induced / Q000000981:diagnostic imaging; D010710:Phosphates / Q000378:metabolism*; D011446:Prospective Studies; D065608:Renal Reabsorption / Q000187:drug effects; D012307:Risk Factors; D000068698:Tenofovir; D013997:Time Factors; D016896:Treatment Outcome; D055815:Young Adult
chemical_list: D000998:Antiviral Agents; D063065:Organophosphonates; D010710:Phosphates; D000068698:Tenofovir; D000225:Adenine