title: The effect of tenofovir on vitamin D metabolism in HIV-infected adults is dependent on sex and ethnicity.
abstract: BACKGROUND
  Tenofovir has been associated with renal phosphate wasting, reduced bone mineral density, and higher parathyroid hormone levels. The aim of this study was to carry out a detailed comparison of the effects of tenofovir versus non-tenofovir use on calcium, phosphate and, vitamin D, parathyroid hormone (PTH), and bone mineral density.
  
  
  METHODS
  A cohort study of 56 HIV-1 infected adults at a single centre in the UK on stable antiretroviral regimes comparing biochemical and bone mineral density parameters between patients receiving either tenofovir or another nucleoside reverse transcriptase inhibitor.
  
  
  RESULTS
  In the unadjusted analysis, there was no significant difference between the two groups in PTH levels (tenofovir mean 5.9 pmol/L, 95% confidence intervals 5.0 to 6.8, versus non-tenofovir; 5.9, 4.9 to 6.9; p = 0.98). Patients on tenofovir had significantly reduced urinary calcium excretion (median 3.01 mmol/24 hours) compared to non-tenofovir users (4.56; p<0.0001). Stratification of the analysis by age and ethnicity revealed that non-white men but not women, on tenofovir had higher PTH levels than non-white men not on tenofovir (mean difference 3.1 pmol/L, 95% CI 5.3 to 0.9; p = 0.007). Those patients with optimal 25-hydroxyvitamin D (>75 nmol/L) on tenofovir had higher 1,25-dihydroxyvitamin D [1,25(OH)(2)D] (median 48 pg/mL versus 31; p = 0.012), fractional excretion of phosphate (median 26.1%, versus 14.6; p = 0.025) and lower serum phosphate (median 0.79 mmol/L versus 1.02; p = 0.040) than those not taking tenofovir.
  
  
  CONCLUSIONS
  The effects of tenofovir on PTH levels were modified by sex and ethnicity in this cohort. Vitamin D status also modified the effects of tenofovir on serum concentrations of 1,25(OH)(2)D and phosphate.
authors.affiliation: Institute of Health and Biomedical Innovation, Queensland University of Technology, Brisbane, Australia. k.klassen@qut.edu.au
authors.forename: Karen
authors.initials: K
authors.lastname: Klassen
authors.forename: Adrian R
authors.initials: AR
authors.lastname: Martineau
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Wilkinson
authors.forename: Graham
authors.initials: G
authors.lastname: Cooke
authors.forename: Alan P
authors.initials: AP
authors.lastname: Courtney
authors.forename: Mary
authors.initials: M
authors.lastname: Hickson
mesh_terms: D000225:Adenine / Q000031:analogs & derivatives* / Q000494:pharmacology; D000328:Adult; D019380:Anti-HIV Agents / Q000494:pharmacology*; D015519:Bone Density; D002118:Calcium / Q000378:metabolism; D015331:Cohort Studies; D005006:Ethnicity; D005260:Female; D015658:HIV Infections / Q000188:drug therapy* / Q000208:ethnology; D006801:Humans; D008297:Male; D008875:Middle Aged; D063065:Organophosphonates / Q000494:pharmacology*; D010281:Parathyroid Hormone / Q000378:metabolism; D010710:Phosphates / Q000378:metabolism; D011446:Prospective Studies; D012044:Regression Analysis; D012737:Sex Factors; D000068698:Tenofovir; D014807:Vitamin D / Q000378:metabolism*
chemical_list: D019380:Anti-HIV Agents; D063065:Organophosphonates; D010281:Parathyroid Hormone; D010710:Phosphates; D014807:Vitamin D; D000068698:Tenofovir; D000225:Adenine; D002118:Calcium