Résumé
Tubulopathy with hypophosphatemia have been observed in HIV-positive patients receiving a tenofovir-containing regimen. However, the real incidence and prevalence of hypophosphatemia and their relation to tubular reabsorption disorders in tenofovir-treated patients remain uncertain. The aim of our study was to explore the effect of tenofovir on phosphatemia and on tubular phosphate reabsorption.
In a first transversal study, 145 HIV-positive adults (44±9 years) receiving tenofovir 300
mg daily with a mean exposure of 11±9 months were included. In a second prospective study, 29 HIV-positive antiretroviral experienced adults (44±10 years) were evaluated before introduction of tenofovir 300
mg daily (M0) and at 3 months (M3) and 6 months (M6), thereafter. Phosphate, creatinine, glucose and protein levels were determined in plasma and urine. The ratio of maximal reabsorption capacity (TmPO4)/glomerular filtration rate (GFR) was determined by using the normogramm of Walton and Bijvoet.
In the transversal study, 26% of patients had hypophosphatemia (<0.84
mmol/l) while 47% of patients had a decreased TmPO4/GFR (<0.8
mmol/l). In the prospective study, baseline prevalence of hypophosphatemia (<0.84
mmol/l) and decreased TmPO4/GFR (<0.8
mmol/l) was 31 and 41%, respectively. Three and 6 months after starting tenofovir, there is no significant change in mean phosphate levels (M0:0.91
mmol/l, M3:0.97
mmol/l, M6:0.98
mmol/l) and mean TmPO4/GFR (M0:0.80
mmol/l, M3:0.88
mmol/l, M6:0.84
mmol/l). Moreover, prevalence of hypophosphatemia (M3:28%, M6:28%) and decreased TmPO4/GFR (M3:41%, M6:45%) remained stable.
Hypophosphatemia linked to a decreased proximal tubular reabsorption was frequently observed in HIV-positive adults independently of the use of tenofovir. In this preliminary study, no worsening effect on phosphatemia and tubular phosphate reabsorption was observed 6 months after introduction of tenofovir in treatment experienced patients.