Leptin (from the Greek word leptos, meaning thin) is a 16-kDa protein hormone
that plays a crucial role in regulating energy intake and energy expenditure, including the
regulation (decrease) of appetite and (increase) of metabolism. Serum leptin concentrations
can be measured in several ways. One approach uses a radioimmunoassay in venous blood
samples (Linco Research Inc., St Charles, MO). Several studies have consistently found
women to have higher serum leptin concentrations than do men. For example, among US
adults across a broad age range, the mean serum leptin concentration in women is
approximately normal π(12.7ππ/πΏ, (1.3ππ/πΏ)2) and in men approximately normal π(4.6ππ/πΏ,
(0.5ππ/πΏ)2).