Avaliação da gordura abdominal por tomografia computadorizada e correlação com níveis de leptina em homens com lipodistrofia associada ao HIV/ Assessment of abdominal fat by computed tomography and correlation with leptin levels in men with HIV-associated lipodystrophy

Abstract

Background: Leptin is an essential hormone in the control of energy homeostasis, whose production and action may be altered in patients with lipodystrophy. Leptin synthesis occurs mainly in adipose tissue, therefore it depends on the amount of body fat. This study aimed to assess the abdominal fat of patients with HIV-associated lipodystrophy and its relationship with leptin levels. Methods: Analytical cross-sectional study involving 40 male patients with HIV-associated lipodystrophy. Serum levels of leptin were measured by ELISA, and insulin levels were measured by a chemiluminescence assay. HOMA-IR was used to evaluate insulin resistance: fasting serum insulin (μIU/mL) × (fasting plasma glucose (mmol/L)/22.5). Total body fat was estimated by skinfold measurements and bioimpedance. Patients with mixed lipodystrophy underwent abdominal CT for subcutaneous and visceral fat measurements, and the visceral-to-subcutaneous fat ratio (VSR) was calculated. Spearman correlation was applied for quantitative associations. Measures of central tendency were compared by the t-test or Mann-Whitney test, and analyses of variance were performed by Kruskal-Wallis test. Results: Forty patients, aged between 35 and 74 years, were evaluated: 27 with mixed lipodystrophy, 10 with lipoatrophy, and 3 with lipohypertrophy. Leptin levels correlated significantly with body fat percentage, BMI, and waist circumference, but not with age. Median levels of leptin were lower in patients with lipoatrophy compared to patients with mixed lipodystrophy (p=0.0393). According to CT results, 70,4% of the patients were classified as VSR>1, and 29,6% as VSR≤1. Significant correlations were found between leptin and visceral fat (CT), insulin, and HOMA-IR, but not between leptin and subcutaneous fat (CT). Conclusions: Our preliminary results suggest that body fat, especially the visceral component, remains the central determinant of leptin levels in patients with mixed lipodystrophy. Also, higher levels of leptin seem to be related to insulin resistance in patients with HIV-associated lipodystrophy, regardless of clinical form.

Uma visão geral sobre o vírus da Imunodeficiência Humana (HIV) e suas possíveis alterações endócrinas no organismo do paciente

“…19 O estudo transversal-analítico de Mourão, L. F. R. De M., et al envolvendo 40 pacientes mostrou que a maioria dos pacientes apresentou a forma mista de lipodistrofia, com aumento da circunferência abdominal às custas de gordura subcutânea e visceral, conforme demonstrado nos resultados de tomografia computadorizada. 20 Em indivíduos afetados pelo vírus da imunodeficiência humana (HIV), foram identificadas modificações corporais congruentes com a lipodistrofia, evidenciando, ademais, disparidades nos níveis lipídicos. No âmbito dessas alterações metabólicas, destaca-se o aumento da resistência periférica à insulina, o surgimento de diabetes mellitus e perturbações nos lipídios, na distribuição da gordura corporal, acidose lática e osteopenia.…”