Research Article: Assessing the Association between Leptin and Bone Mineral Density in HIV-Infected Men

Date Published: August 27, 2012

Publisher: Hindawi Publishing Corporation

Author(s): Madhu N. Rao, Morris Schambelan, Viva W. Tai, Donald I. Abrams, Hootan Khatami, Peter J. Havel, Giorgos Sakkas, Kathleen Mulligan.

http://doi.org/10.1155/2012/103072

Abstract

HIV-infected individuals are at risk for decreased bone mineral density (BMD). The known risk factors for bone loss do not fully explain the increased risk in this population. There is emerging evidence that leptin, a hormone secreted by adipocytes, plays an important role in bone metabolism. Several studies have assessed the relationship between leptin and bone density in healthy adults, but there are few such studies in HIV-infected individuals. Furthermore, HIV infected individuals on antiretroviral therapy are at increased risk for altered fat distribution, which may impact the relationship between leptin and BMD. In a cross-sectional analysis of data in 107 HIV-infected men, we determined whether serum leptin levels were associated with whole-body BMD and bone mineral content measured by dual-energy X-ray absorptiometry (DEXA), after adjusting for confounders including body fat distribution. We found an inverse association between leptin and bone density in those with peripheral lipoatrophy, defined objectively as <3 kg appendicular fat by DEXA, but no such relationship was seen in those with >3 kg appendicular fat. This result suggests that fat distribution may modify the relationship between leptin and bone density.

Partial Text

Patients with HIV infection are at risk for decreased bone density [1]. This is due to both HIV-specific factors (i.e., use of tenofovir, starting antiretroviral therapy) and generalized factors that are present in this population (including hypogonadism, smoking, alcohol use, and low body weight). However, these etiologies do not fully explain the increased risk for bone loss that is observed [2–4]. In non HIV-infected populations, there is evidence that leptin, a hormone mainly secreted by adipocytes, plays an important role in bone metabolism [5]. In healthy adults, increased fat mass is associated with increased bone density [5] as well as increased circulating leptin concentrations. This has led to the suggestion that leptin may mediate the positive effects of fat mass on bone density.

In this analysis of data in a diverse group of 107 HIV-infected men, we found no statistically significant relationship between serum leptin levels and whole-body BMD or BMC. However, in the 33 subjects with <3 kg of appendicular fat, we found a robust inverse association between leptin and bone density that was statistically significant, despite the small number of subjects. Adjusting the model for potential confounders such as age, race, LBM, serum insulin, and total and trunk fat did not significantly change the results.   Source: http://doi.org/10.1155/2012/103072

 

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