Serum leptin and bone metabolism in HIV patients treated with highly active antiretroviral therapy

The role of leptin in bone metabolism has not yet been fully elucidated and results remain controversial. We investigated whether changes in serum leptin correlated to bone mineral density (BMD) occur in human immunodeficiency virus (HIV) patients on highly active antiretroviral therapy (HAART).

The study population was 117 HIV patients (67 men, 50 women) on HAART and 50 healthy controls, all with normal body mass index (BMI). Based on whole body BMD as measured by dual energy x-ray absorptiometry (DEXA), patients were classified as having a low (< -1) T-score (L) or a normal (> -1) T-score (N); DEXA scans were also used to determine total body fat (TFM) and percent fat (F%); radioimmunologic assays were used to measure leptin, osteocalcin (OC), bone alkaline phosphatase (BAP), 1,25 (OH)2 D in serum, and pyridinium cross-links (PYD & DPD) in urine.

Of the 117 HIV patients, 54 (46.1%) were classified as L and 63 (53.9%) as N; BMD in both sexes was lower (P <0.01) among the L patients than among either the N patients or the controls; 25/32 L men and 19/22 women were osteopenic, the remaining were osteoporotic. The mean TFM, F%, OC, BAP and PYD & DPD values were higher and the mean 1,25 (OH)2 D values were lower in the L than in the N patients; leptin was higher among the L men (P <0.002) and the L women (P <0.03) than in the N patients. In both sexes. leptin positively correlated with TFM, F%, BAP and PYD & DPD; however, leptin, TFM and F% correlated negatively with BMD. A negative correlation was found between 1,25 (OH)2 D and PYD & DPD in women. At follow-up assessment of 56 HIV patients continuing HAART, leptin and BAP increased and 1,25 (OH)2 D decreased, but not significantly; BMD significantly decreased in women and PYD & DPD increased in men (P <0.02).

An inverse relationship was found between leptin and BMD in HIV patients with osteopenia/osteoporosis treated with HAART. While the role of leptin in bone metabolism in a setting of HIV is still unclear, an inhibitory effect of leptin associated with a negative action by HAART may be hypothesized.