Secondary hyperparathyroidism in HIV patients: is there any responsibility of highly active antiretroviral therapy?

Switching tenofovir disoproxil fumarate to tenofovir alafenamide results in a significant decline in parathyroid hormone levels: uncovering the mechanism of tenofovir disoproxil fumarate-related bone loss?

: An increasing number of patients have been switched from tenofovir disoproxil fumarate (TDF) to tenofovir alafenamide because of its improved bone safety profile, although the pathophysiological mechanism is not fully understood. We show that serum parathyroid hormone levels drop significantly after the switch from TDF to tenofovir alafenamide. This observation supports the theories that TDF-related bone loss is parathyroid hormone-driven and that this effect is dose-dependent.

Tenofovir disoproxil fumarate/emtricitabine is associated with a higher risk of hypocalcemia compared to abacavir/lamivudine - results from a German cohort study

Hyperparathyroidism has been described in people living with HIV undergoing tenofovir disoproxil fumarate (TDF)-containing antiretroviral therapy (ART), but differences in calcium levels have never been investigated in detail. We aimed to compare the prevalence of hypocalcemia between patients with and without TDF-containing ART. The patients and methods were a retrospective cohort study in HIV-infected adult patients receiving dolutegravir and either abacavir (ABC)/lamivudine (3TC) or TDF/emtricitabine in a single center in Munich, Germany. Of 172 patients, 126 (73.3%) were male and the median age was 48.5 years (interquartile range 42-54). Average calcium levels were 2.24 (2.21-2.29) mmol/l and 2.21 (2.16-2.26) mmol/l (P < 0.001) with a prevalence of at least one episode of total calcium <2.12 mmol/l of 16.2 and 34.4% in the groups treated with ABC/3TC and TDF/emtricitabine, respectively (P = 0.006). TDF use was independently associated with the occurrence of albumin-corrected calcium levels of <2.12 mmol/l (odds ratio: 6.7 [1.3-35.6]; P = 0.025). Hypocalcemia seems to occur more often in TDF-treated patients. Further research into hypocalcemia with TDF and potential cardiovascular effects may be of benefit based on these findings.

The impact of vitamin D supplementation on musculoskeletal health outcomes in children, adolescents, and young adults living with HIV: A systematic review

OBJECTIVE

HIV-positive children, adolescents, and young adults are at increased risk poor musculoskeletal outcomes. Increased incidence of vitamin D deficiency in youth living with HIV may further adversely affect musculoskeletal health. We investigated the impact of vitamin D supplementation on a range of musculoskeletal outcomes among individuals aged 0-25 years living with HIV.

METHODS

A systematic review was conducted using databases: PubMed/Medline, CINAHL, Web of Knowledge, and EMBASE. Interventional randomised control trials, quasi-experimental trials, and previous systematic reviews/meta-analyses were included. Outcomes included: BMD, BMC, fracture incidence, muscle strength, linear growth (height-for-age Z-score [HAZ]), and biochemical/endocrine biomarkers including bone turnover markers.

RESULTS

Of 497 records, 20 studies met inclusion criteria. Thirteen studies were conducted in North America, one in Asia, two in Europe, and four in Sub-Saharan Africa. High-dose vitamin D supplementation regimens (1,000-7,000 IU/day) were successful in achieving serum 25-hydroxyvitamin-D (25OHD) concentrations above study-defined thresholds. No improvements were observed in BMD, BMC, or in muscle power, force and strength; however, improvements in neuromuscular motor skills were demonstrated. HAZ was unaffected by low-dose (200-400 IU/day) supplementation. A single study found positive effects on HAZ with high-dose supplementation (7,000 vs 4,000IU/day).

CONCLUSIONS

Measured bone outcomes were unaffected by high-dose vitamin D supplementation, even when target 25OHD measurements were achieved. This may be due to: insufficient sample size, follow-up, intermittent dosing, non-standardised definitions of vitamin D deficiency, or heterogeneity of enrolment criteria pertaining to baseline vitamin D concentration. High-dose vitamin D may improve HAZ and neuromuscular motor skills. Adequately powered trials are needed in settings where HIV burden is greatest. PROSPERO Number: CRD42016042938.

Monitoring early developed low bone mineral density in HIV-infected patients by intact parathyroid hormone and circulating fibroblast growth factor 23

BACKGROUND/PURPOSE

HIV-infected patients have a high prevalence of low bone mineral density (BMD), but BMD changes remain unclear. This cross-sectional retrospective observational study aimed to characterize the prevalence and associated factors of low BMD in HIV patients.

METHODS

Between 1 January 2015 and 31 December 2016, all patients aged 20 years or greater who sought for HIV care were included. BMD was measured by dual-energy X-ray absorptiometry. Multivariable analyses of the association with HIV disease status, treatment and anthropometric parameters were performed. Circulating fibroblast growth factor 23 and intact parathyroid hormone were measured.

RESULTS

A total of 137 patients was included; their median age was 39 years old; 97.8% were treated with combination antiretroviral therapy (cART); Body mass index (BMI) was 21.97 kg/m². Sixty-one patients (44.5%) showed low BMD (osteopenia and osteoporosis) based on the WHO criteria. The median BMD was -0.80 g/cm² (IQR, -1.5 to -0.2). The prevalence rate of low BMD was 37% in those who were aged 20-29 years, 45.2% in those who were aged 30-39 years, 45.2% in those who were aged 40-49 years, 45.8% in those who were aged 50-59 years, and 53.8% in those who were aged ≧60 years. More than half of patients (50.4%, 69/137) were younger than 40 years. Compared with normal BMD group, the low BMD group has a higher proportion of secondary hyperparathyroidism (18.0% vs 5.3%, p: 0.026) and a lower median C-terminal FGF23 level (48.92 vs 62.61 pg/ml, p: 0.008). Univariate and multivariate analyses of the factors associated with low BMD. We found that only serum intact-parathyroid hormone (iPTH) > 69 pg/ml (OR, 3.86; 95% CI, 1.14-13.09) was statistically significant associated with low BMD in multivariate analysis.

CONCLUSIONS

This cohort-based survey showed a high prevalence of low BMD among HIV-infected adults which included young-age patient in an university hospital. Secondary hyperparathyroidism was significantly associated with low BMD. There was no association between FGF23 and low BMD.

People Living With HIV: Implications for Rehabilitation Nurses

PURPOSE

The aim of this study was to present a brief overview of challenges faced by people living with HIV (PLHIV) as they age, to discuss the relevance of HIV to rehabilitation nurses, and to provide evidence-based recommendations for rehabilitation professionals working with PLHIV.

DESIGN

Current issues article.

METHODS

Literature review related to age-related comorbidities in PLHIV with implications for rehabilitation nurses.

FINDINGS

Rehabilitation nurses must be prepared to address issues specific to people living with HIV including sensitivity and privacy regarding HIV status and increased risk of delayed or complicated healing. Rehabilitation nurses should also promote self-management behavior to optimize health in people living with HIV.

CONCLUSIONS

Understanding unique characteristics of PLHIV as well as applying focused assessment and tailored interventions in PLHIV will give rehabilitation nurses the tools to successfully guide PLHIV through the rehabilitation process and optimize clinical outcomes.

CLINICAL RELEVANCE

As people with HIV age and experience acute and chronic comorbidities, they will require the clinical expertise of rehabilitation nurses in the process to successfully transition through acute and subacute health care and regain function.

Bone turnover markers in HIV-infected women on tenofovir-based antiretroviral therapy

Background: Tenofovir disoproxil fumarate (TDF) antiretroviral therapy is associated with disruption of the bone turnover process.Objectives: The objective of this study was to determine the association between tenofovir (TFV) plasma concentration and various bone turnover markers and compare these markers in HIV-infected women and HIV-uninfected controls.Method: A cross-sectional sub-study included 30 HIV-infected women on TDF and 30 HIV-uninfected matched participants. Serum calcium (SrCa), serum phosphate (SrP), C-terminal telopeptide (CTx), parathyroid hormone (PTH), alkaline phosphatase (ALP), C-reactive protein (CRP), vitamin D (VitD) and bone mineral density (BMD) were measured. Plasma TFV was assayed on HPLC-MS/MS. The statistical tests applied were Mann–Whitney test, unpaired t-test, analysis of covariance, regression and correlation analysis.Results: In HIV-infected women, no correlation existed between plasma TFV concentration and CTx, PTH, ALP, SrCa, SrP, VitD or BMD (p > 0.05). After adjusting for smoking and alcohol use, ALP (p < 0.001), CTx (p = 0.027) and PTH (p = 0.050) were significantly higher in HIV-infected compared to HIV-uninfected women. Women with TFV concentration ≥ 120 ng/mL had higher PTH concentrations (p = 0.037) compared to those with ≤ 100 ng/mL. Significant correlations between SrCa and PTH and SrCa and SrP including CTx and PTH (p < 0.05) were present in HIV-uninfected women while absent in HIV-infected counterparts (p > 0.05).Conclusion: The results indicate possible increased bone turnover at higher TFV concentrations. The normal regular bone turnover processes in HIV-infected women on TDF therapy are altered. Larger studies are warranted to confirm these results.

High parathyroid hormone concentration in tenofovir-treated patients are due to inhibition of calcium-sensing receptor activity

Bone health impairment is a common finding in HIV-infected patients on antiretroviral treatment. High serum parathyroid hormone (PTH) concentration in patients on antiretroviral treatment containing tenofovir disoproxil fumarate (TDF) has been reported. Hyperparathyroidism was not always sustained by a reduction in vitamin D concentration. We thus hypothesized a direct inhibitory effect of TDF on the Calcium-sensing receptor (CaSR), leading to hyperparathyroidism. Human embryonic kidney cells were transfected with CASR wild-type gene or mutated in different sites (N124K, T1051G, C788T, T888M). Cells were grown in standard conditions and the activity of CaSR was assessed after stimulation with CaCl₂ with and without TDF (100 nM-1 μM). We evaluated by western blot phospho-p44/42 ERK expression levels as a marker of CaSR activity. In silico structure models were obtained for wild-type and N124K mutant. Molecular docking with TDF was also evaluated. The stimulation by CaCl₂ and TDF 100 nM led to a decrease of 55% of CaSR activity (P < 0.001), whereas the stimulation by CaCl₂ and TDF 1 μM reduced the activity by 68% (P < 0.001). The decreased CaSR activity was comparable to that observed from known CASR gene inactivating mutations (T1051G, C788T), which inhibit the receptor activity by 56% and 78%, respectively. The TDF inhibits the CaSR activity carrying a gain of function mutation in the intracellular domain (T888M), but it does not influence the activity of the receptor carrying the N124K activating mutation. Our data show that TDF is able to inhibit the activity of CaSR in a dose-dependent manner. Hyperparathyroidism observed in TDF-treated patients may be therefore promoted by the direct effect of the drug on CaSR.

Validation Protocol of Vitamin D Supplementation in Patients with HIV-Infection

Hypovitaminosis D and secondary hyperparathyroidism are frequent among HIV-infected patients. As there are no data about the best supplementation therapy both in treatment and in maintenance, we conducted an observational study of 300 HIV-infected patients for whom vitamin D and parathormone (PTH) had been measured in order to validate a protocol of vitamin D supplementation in patients with HIV-infection. Patients with vitamin D deficiency (defined as 25(OH)D < 10 ng/mL), insufficiency (defined as 25(OH)D < 20 ng/mL), or hyperparathyroidism (PTH > 65 pg/mL) were supplemented with cholecalciferol 16.000IU (0.266 mg) weekly (if deficiency) or fortnightly (if insufficiency or high PTH levels). Rates of normalization of 25(OH)D (levels above 20 ng/mL) and PTH levels (<65 pg/mL) were analyzed. Multivariate analysis of factors related to normalization was carried out. With a median follow-up of 2 years, 82.1% of patients with deficiency and 83.9% of cases with insufficiency reached levels above 20 ng/mL. However, only 67.2% of individuals with hyperparathyroidism at baseline reached target levels (<65 pg/mL). Independent factors for not achieving PTH objective were tenofovir (TDF) and protease inhibitors use. In HIV-infected patients with hypovitaminosis, the protocol of cholecalciferol supplementation normalized vitamin D levels regardless of antiretroviral regimen in a high proportion of patients but it was less effective to correct hyperparathyroidism.

The effect of tenofovir on vitamin D metabolism in HIV-infected adults is dependent on sex and ethnicity

Background

Tenofovir has been associated with renal phosphate wasting, reduced bone mineral density, and higher parathyroid hormone levels. The aim of this study was to carry out a detailed comparison of the effects of tenofovir versus non-tenofovir use on calcium, phosphate and, vitamin D, parathyroid hormone (PTH), and bone mineral density.

Methods

A cohort study of 56 HIV-1 infected adults at a single centre in the UK on stable antiretroviral regimes comparing biochemical and bone mineral density parameters between patients receiving either tenofovir or another nucleoside reverse transcriptase inhibitor.

Principal Findings

In the unadjusted analysis, there was no significant difference between the two groups in PTH levels (tenofovir mean 5.9 pmol/L, 95% confidence intervals 5.0 to 6.8, versus non-tenofovir; 5.9, 4.9 to 6.9; p = 0.98). Patients on tenofovir had significantly reduced urinary calcium excretion (median 3.01 mmol/24 hours) compared to non-tenofovir users (4.56; p<0.0001). Stratification of the analysis by age and ethnicity revealed that non-white men but not women, on tenofovir had higher PTH levels than non-white men not on tenofovir (mean difference 3.1 pmol/L, 95% CI 5.3 to 0.9; p = 0.007). Those patients with optimal 25-hydroxyvitamin D (>75 nmol/L) on tenofovir had higher 1,25-dihydroxyvitamin D [1,25(OH)₂D] (median 48 pg/mL versus 31; p = 0.012), fractional excretion of phosphate (median 26.1%, versus 14.6; p = 0.025) and lower serum phosphate (median 0.79 mmol/L versus 1.02; p = 0.040) than those not taking tenofovir.

Conclusions

The effects of tenofovir on PTH levels were modified by sex and ethnicity in this cohort. Vitamin D status also modified the effects of tenofovir on serum concentrations of 1,25(OH)₂D and phosphate.

Effects of vitamin D deficiency and combination antiretroviral therapy on bone in HIV-positive patients

OBJECTIVES

In the era of combination antiretroviral therapy (cART), vitamin D deficiency, low bone mineral density (BMD) and fractures have emerged as subjects of concern in HIV-positive patients. Testing for vitamin D deficiency has been widely adopted in clinical practice even though the benefits of vitamin D supplementation in this population remain uncertain. The objective of this review was to evaluate the evidence for such a strategy.

DESIGN

Systematic review of the literature on vitamin D deficiency in HIV infection, the effects of cART on vitamin D status, and the effects of vitamin D deficiency and cART on parathyroid hormone (PTH), bone turnover, BMD and the incidence of fractures in HIV-positive patients.

METHODS

PubMed was used to identify relevant articles up to September 2011.

RESULTS

Vitamin D deficiency, secondary hyperparathyroidism and low BMD are common in HIV-positive patients. Efavirenz is associated with a reduction in 25-hydroxy vitamin D levels, tenofovir with secondary hyperparathyroidism, and cART with increased bone turnover and low BMD. The clinical significance of low BMD, however, remains unclear, especially in younger patients. Although the incidence of fractures may be increased in HIV-positive patients, the contribution of low BMD and vitamin D deficiency to these fractures is uncertain. Limited data on vitamin D supplementation in HIV-positive patients have shown transient, beneficial effects on PTH, but no effects on BMD.

CONCLUSION

The benefits of vitamin D supplementation in this population need to be demonstrated before widespread 'test and treat' policies can be recommended as part of routine clinical practice.