Serum leptin levels in the acquired immunodeficiency syndrome.

Leptin, a hormone that is secreted by adipose tissue in proportion to fat stores, regulates energy balance and appetite. Recently, tumor necrosis factor and interleukin-1, cytokines that regulate the host response to infection, have been shown to acutely increase leptin levels, raising the possibility that leptin could mediate the anorexia of some infections. We measured leptin levels in patients with the acquired immunodeficiency syndrome and found that leptin levels were not increased relative to body fat in patients who were anorectic, were losing weight, or had a history of weight loss. Furthermore, leptin levels were not increased during secondary infection, suggesting that elevations in leptin do not play a key role in the anorexia of infections associated with acquired immunodeficiency syndrome.