title: Tenofovir monotherapy for hepatitis B after 1 year does not produce renal dysfunction, but is associated with hyperparathyroidism not related to vitamin D.
abstract: BACKGROUND
  Viral hepatitis B (VHB) represents a major public health problem. Studies from HIV multidrug patients have associated the use of tenofovir disoproxil fumarate (TDF) with renal dysfunction and phosphate wasting.
  
  
  OBJECTIVE
  The aim of this study was to examine the effect of year-long TDF monotherapy on renal function in VHB patients.
  
  
  METHODS
  We evaluated adult patients diagnosed with VHB before treatment initiation (T0), and after 3 and 12 months (T3 and T12) of TDF initiation. Estimated glomerular filtration rate (eGFR) was estimated by serum cystatin C and creatinine. In addition, urinary electrolytes and tubular biomarkers (cystatin C, β2-microglobulin and neutrophil gelatinase-associated lipocalin) were analyzed, as well as parathyroid hormone (PTH) and 25(OH)vitamin D levels.
  
  
  RESULTS
  After 1 year, 32 patients completed the study, 22 (68.7%) men and 12 (37.5%) Whites, mean age 44.1±12.0 years. We found that serum electrolytes were similar at baseline and 3 or 12 months after initiation of TDF monotherapy. In addition, urinary fractional excretions of electrolytes as well as proteinuria, albuminuria, urinary β2-microglobulin, and urinary cystatin C showed no significant differences across the treatment timeline. There were also no statistical differences in the eGFR. There was a statistically significant increase in the PTH (Friedman's test, P=0.012), but the 25(OH)vitamin D levels were in the normal range in the beginning and did not change at the follow-up. Moreover, there was no correlation between the initial levels of vitamin D and the corresponding increases in the PTH values.
  
  
  CONCLUSIONS
  If used as monotherapy in hepatitis B patients for a 12-month period, TDF is not associated with changes in either eGFR or a panel of urinary biomarkers. Serum and urinary electrolytes also remained unchanged. Of note, a significant increase in the PTH was found, although not related to the 25(OH)vitamin D initial status.
authors.affiliation: aNephrology Unit bGastroenterology Unit, Department of Internal Medicine cClinical Biochemistry/Immunology Unit, Department of Pathology dProgram in Medical Sciences, Hospital Universitario Antonio Pedro, Fluminense Federal University, Rio de Janeiro, Brazil.
authors.forename: Jose A
authors.initials: JA
authors.lastname: Patricio
authors.forename: Patricia F
authors.initials: PF
authors.lastname: Lopes
authors.forename: Thalia
authors.initials: T
authors.lastname: Medeiros
authors.forename: Guilherme F
authors.initials: GF
authors.lastname: Mendes
authors.forename: Andrea A
authors.initials: AA
authors.lastname: Silva
authors.forename: Eliane B
authors.initials: EB
authors.lastname: Esberard
authors.forename: Jocemir R
authors.initials: JR
authors.lastname: Lugon
authors.forename: Jorge R
authors.initials: JR
authors.lastname: Almeida
mesh_terms: D000328:Adult; D000419:Albuminuria / Q000652:urine; D000469:Alkaline Phosphatase / Q000097:blood; D000998:Antiviral Agents / Q000009:adverse effects*; D003404:Creatinine / Q000097:blood; D055316:Cystatin C / Q000652:urine; D004573:Electrolytes / Q000097:blood / Q000652:urine; D005260:Female; D005919:Glomerular Filtration Rate; D006509:Hepatitis B / Q000188:drug therapy*; D006801:Humans; D006961:Hyperparathyroidism / Q000097:blood / Q000139:chemically induced*; D008297:Male; D008875:Middle Aged; D010281:Parathyroid Hormone / Q000097:blood; D051437:Renal Insufficiency / Q000139:chemically induced* / Q000652:urine; D012709:Serum Albumin / Q000378:metabolism; D000068698:Tenofovir / Q000009:adverse effects*; D014508:Urea / Q000097:blood; D014527:Uric Acid / Q000097:blood / Q000652:urine; D014807:Vitamin D / Q000097:blood; D001613:beta 2-Microglobulin / Q000097:blood / Q000652:urine
chemical_list: D000998:Antiviral Agents; D055316:Cystatin C; D004573:Electrolytes; D010281:Parathyroid Hormone; D012709:Serum Albumin; D001613:beta 2-Microglobulin; D014807:Vitamin D; D014527:Uric Acid; D014508:Urea; D000068698:Tenofovir; D003404:Creatinine; D000469:Alkaline Phosphatase