Endocrine Abstracts

Background: HIV is associated with decreased bone mineral density (BMD) and decreased muscle mass. Osteoporosis and sarcopenia often co-exist and their onset is multifactorial. Sex steroids play a key role in the homeostasis of bone health and body composition in HIV-uninfected men, but data in MLWH are scanty.

Aim: To investigate the frequency of low BMD and sarcopenia and their relationship with gonadal function in MLWH younger than 50.

Methodology: Prospective, cross-sectional, observational study on MLWH with ongoing antiretroviral therapy. Body composition and BMD were obtained by dual-energy X-ray absorptiometry (DXA). Sarcopenia was defined as appendicular lean mass/height² (ALMI) <7.26 kg/m²; low BMD was defined for Z-score <2.0 at lumbar or femoral site. Patients were classified according to body mass index (BMI) and body fat percentage: hidden obesity was defined wherein BMI was 18.5-25.0 kg/m² and the body fat percentage was >20%. Serum total testosterone (TT) and estradiol (E2) were measured by liquid chromatography-tandem mass spectrometry; free testosterone (cFT) was calculated by Vermeulen equation.

Results: A total of 316 MLWH aged 45.3±5.3 years were enrolled. BMD was normal in 265 MLWH (86.0%) and reduced in 43 (14.0%); sarcopenia was detected in 107 MLWH (33.8%). Sarcopenic MLWH had lower cFT (P=0.002), E2 (P=0.002), E2/T ratio (P=0.017), and reduced BMD at both lumbar and femoral site compared to non-sarcopenic patients. Furthermore, sarcopenic patients had lower BMI (P<0.001) along with increased total fat percentage (P=0.038); accordingly, the prevalence of hidden obesity was greater in sarcopenic than non-sarcopenic subgroup (71.0% vs 37.7%; P<0.001). The E2/TT ratio was lower in patients with low BMD compared to those with normal BMD (P=0.023), although TT, E2, and cFT did not differ. Patients with lower E2/TT values had an increased likelihood risk of sarcopenia (P=0.044) and low BMD (P=0.025). No difference was found for age and HIV duration comparing patients for low BMD or sarcopenia. Finally, ALMI was directly associated with BMD Z-scores at any site.

Conclusions: Sarcopenia and low BMD are common findings among young adult MLWH and these conditions are strictly related each other. Within the multidimensional network of factors leading to reduced BMD and lean mass, an imbalanced E2/TT ratio seems to be more relevant rather than TT or E2 alone. The prevalence of hidden obesity is high, especially in sarcopenic MLWH, and it may be overlooked by weight measurement alone with a consequent undermanagement of the increased cardiometabolic risk.