De-escalating to DTG monotherapy in selected patients might be a safe and feasible option. However, in one case evolution of INSTI resistance was observed. Further studies should assess particular risk factors for DTG monotherapy failure. In the meanwhile, caution is warranted.

Secondary hyperparathyroidism (sHPT) might be a contributor to increased risk of osteoporosis in adult HIV patients but there is little data available on this issue in this particular population. The aim of the study was to investigate the prevalence of sHPT in an HIV-infected population with normal kidney function and to evaluate its risk factors in HIV patients. This cross-sectional study was carried out in a single HIV center in Germany using routine data from patients with normal kidney function attending the clinic between January 1st and December 31st, 2016. In total, 1263 patients were included [998 (79.0%) male, median age 48 (IQR 38-54) years]. In 214 patients (16.9%) elevated PTH levels with low or normal calcium levels were found. Multivariate logistic regression modeling showed significant associations with elevated PTH for African ethnicity [OR: 2.12 (95% CI: 1.42-3.16); p<0.001], low 25-hydroxyvitamin D levels [OR: 1.82 (95% CI: 1.32-2.51); p<0.001], low calcium levels [OR 1.69 (95% CI: 1.22-2.33); p=0.001], and use of tenofovir disoproxil fumarate [OR 2.33 (95% CI: 1.62-3.36); p<0.001]. Additional to common risk factors like vitamin D insufficiency and hypocalcemia, we found a significant association between the use of TDF and sHPT. Prospective data are needed to ascertain whether PTH-mediated bone loss is the underlying mechanism of TDF bone-toxicity. Additional screening of PTH even in HIV-infected patients with normal or low calcium levels may help to identify patients at increased risk of bone mineral density loss.

Introduction: Human immunodeficiency virus (HIV)-infected patients treated with antiretroviral therapy (ART) are at high risk for vitamin D insufficiency, which is essentially caused by interference of medication with vitamin D metabolism. Under these conditions, the preservation of natural seasonal variability in vitamin D concentrations is not self-evident. Yet, for proper screening and interpretation of laboratory findings, knowledge about seasonality is essential. Aim of the study was to describe seasonal behavior in ART-treated HIV-infected patients in Central Europe. Material and methods:It was a retrospective single-center study. Patients' medical records were screened for serum vitamin D levels, β-crosslaps, and surrogate values of bone turnover.Results: A total of 1011 datasets (625 patients) were evaluated. Overall, the median vitamin D level was 19.6 µg/l. In 207 (16.4%) datasets, patients were receiving oral cholecalciferol supplementation. Seasonal changes in serum vitamin D levels were reflected by minimum levels (median 13.5 µg/l) in March and maximum levels (median 23.7 µg/l) in July (p < 0.001). In contrast, serum calcium levels were lowest in September and October (2.23 mmol/l) and highest in May (2.32 mmol/l). Conclusions:Significant variation in seasonal serum vitamin D levels was found in an unselected population of HIV-infected patients. This finding is in line with results from HIV-negative populations. Accordingly, the time point of vitamin D testing might be crucial for appropriate diagnosis of hypovitaminosis. We recommend vitamin D testing between December and May to provide the highest sensitivity. As serum calcium levels did not demonstrate the same pattern, the meaning of this finding is unclear and warrants further investigation.

Background Higher levels of parathyroid hormone have been associated with the use of tenofovir disoproxil fumarate (TDF) in people with and without HIV infection. Yet, alterations in calcium levels have never been elucidated in detail. Objective To compare the association of parathyroid hormone with serum calcium levels and other markers of calcium and bone metabolism in people living with HIV on TDF- and non-TDF-containing antiretroviral therapy. Patients and Methods A retrospective single center cohort study in Munich, Germany. Median and interquartile ranges and absolute and relative frequencies were used to describe continuous and categorical variables, respectively. The Mann–Whitney U test and chi2-test were used for comparisons. Multivariate median regression was performed in a stepwise backward approach. Results 1,002 patients were included (786 (78.4%) male; median age 48 (40–55) years). 564 patients (56.3%) had a TDF-containing ART regimen. PTH concentrations were 46.9 (33.0–64.7) pg/mL and 35.2 (26.4–55.4) pg/mL (P=0.001), 43.3 (30.8–59.8) pg/mL and 31.8 (22.3–49.6) pg/mL (P < 0.001), 46.1 (29.5–65.4) pg/mL and 33.4 (22.6–50.1) pg/mL (P < 0.001), and 37.8 (25.3–57.9) pg/mL and 33.8 (20.1–45.3) pg/mL (P=0.012) within the first, second, third, and fourth quartile of corrected calcium levels for patients with and without TDF-containing ART, respectively. In multivariate median regression, PTH concentration was significantly associated with Cacorr. (−32.2 (−49.8 to −14.8); P < 0.001), female sex (5.2 (1.2–9.2); P=0.010), 25(OH)D (−0.4 (−0.5 to −0.3); P < 0.001), and TDF-use (9.2 (6.0–12.5); P < 0.001). Discussion Higher levels of PTH seem to be needed to maintain normal calcium levels in PLWH on TDF-containing ART compared to non-TDF-containing ART. Optimal concentrations for 25-hydroxy vitamin D and calcium might therefore be different in people using TDF than expected from general populations but also people living with HIV with non-TDF-containing antiretroviral therapy. This might require different supplementation strategies but warrants further investigation.

No abstract