|| Checking for direct PDF access through Ovid
To examine longitudinal change in vitamin D binding protein (DBP) levels during the first year after initiation of tenofovir disoproxil fumarate (TDF)/lamivudine/efavirenz and compare these findings with concurrent changes in markers of skeletal metabolism.Secondary analysis of plasma samples collected from an ongoing multicenter clinical trial.Plasma samples collected at 0, 24, and 48 weeks after initiation of TDF + lamivudine + efavirenz from 134 adult participants enrolled in a multicenter randomized trial were analyzed. Data regarding sociodemographic and clinical characteristics were obtained as part of the parent study. Laboratory analyses included plasma DBP, intact parathyroid hormone, total 25-hydroxy vitamin D, phosphorus, the bone resorption marker collagen type 1 cross-linked C-telopeptide, and the bone formation marker total procollagen type 1 N-terminal propeptide. Repeated measures analysis of variance was used to measure changes in biomarkers over time.Our sample included 108 men and 26 women (mean age 33.6 ± 9.6 years). Median levels of DBP increased significantly from baseline to 48 weeks [154 (91.8–257.4) versus 198.3 (119.6–351.9) μg/ml, P < 0.001]. A concurrent rise in intact parathyroid hormone levels was observed over the same period [32.3 (24.4–40.9) versus 45.2 (35.1–60.4) pg/ml, P < 0.001]; however, 25-hydroxy vitamin D and phosphorus levels remained stable. Bone resorption and formation markers rapidly increased from 0 to 24 weeks, followed by a slight decline or plateau, but remained significantly elevated at 48 weeks (P < 0.001).Our study provides longitudinal data supporting a potential role for DBP in bone loss associated with TDF-based therapy. Further research to elucidate the mechanistic pathways and clinical impact of these findings is warranted.