SERUM LEPTIN CONCENTRATIONS IN HUMAN IMMUNODEFICIENCY VIRUS-INFECTED MEN WITH LOW ADIPOSITY

The product of the obese gene (ob) is the protein leptin, which is syn thesized in and secreted from adipocytes, Fasting serum leptin concent rations are closely related to body fat content and are higher in obes e than in normal-weight individuals. Leptin may contribute to body wei ght regulation. Overproduction of leptin in certain pathologic conditi ons such as acquired immunodeficiency syndrome (AIDS) might in princip le contribute to the low body fat content associated with body wasting . We measured fasting serum leptin levels by radioimmunoassay in indiv iduals infected with the human immunodeficiency virus (HIV) and in a g roup of healthy lean men to determine whether HIV infection increases leptin levels. Thirteen HIV-infected men aged 26 to 50 years with a bo dy mass index (BMI) of 15 to 26 kg/m(2) and 4 to 24 kg body fat (7% to 29% body fat) had serum leptin levels (3.4 +/- 1.6 ng/mL) that were n ot elevated compared with the levels in 17 healthy men (4.0 +/- 1.4 ng /mL) matched for age (23 to 47 years), BMI (18 to 26 kg/m(2)), and bod y fat (5 to 21 kg: 9% to 28%). In both groups of men. serum leptin con centrations were correlated with percent body fat and body fat content (P < .001), and these relationships were not different between the tw o groups. In both groups, leptin concentrations were not correlated wi th lean body mass (P greater than or equal to .24). Energy intake in t he HIV-infected men, assessed from 3-day intake records, was within th e normal range, These findings extend the hypothesis that circulating leptin concentrations directly reflect adipose tissue mass, even in HI V-infected men with low body fat content. These findings do not suppor t the hypothesis that HIV infection is associated with high circulatin g leptin concentrations, and suggest that low leptin levels do not sti mulate food intake in HIV-infected individuals. Copyright (C) 1997 by W.B. Saunders Company.