Lack of utility of phosphate serum monitoring in HIV-infected patients on a tenofovir-based antiretroviral regimen

Results Phosphate measurements were obtained in 265 patients during follow-up. Mean age was 40.66 (±7.68) years, 76.2% were men, 47.9% were IDU, and 84.9 % received an antiretroviral regimen based on TDF. At baseline, before antiretroviral therapy, hypophosphatemia was observed in 4 of 67 patients (6%). Overall, during follow up, HP was observed in 56 of 265 (21.1%), but was confirmed only in 33 (12.5%). The median time to HP was 798(±13.95) days, usually with phosphate levels above 2 mg/dl (mild HP). A higher percent of patients prescribed TDF showed a phosphate measurement below normal limits (13.8%) in comparison with those patients receiving non-TDF based therapy (5%), although this comparison was not significant (p=0.103). There was no difference with regard to time to HP in patients receiving TDF or not (median time 798 vs 834 days, p=0.106 log-rank test), neither in the values of serum creatinine or MDRD in patients with or without hypophosphatemia.