Secondary hyperparathyroidism may develop in the presence of hypovitaminosis D in order to maintain calcium homeostasis. We conducted a cross-sectional analysis in a cohort of 371 patients, identifying secondary hyperparathyroidism in 65 patients. This high prevalence (17.5%) was in part justified by the high prevalence of hypovitaminosis D (77.4%) in the whole sample, but we also identified an independent association with the use of tenofovir.