Leptin

Test ID:

702922

CPT code:

83520

Clinical Use:

Assessment of obesity, delayed puberty, and infertility

Test Information:

Leptin is a 16-kilodalton protein that was first identified when it was cloned in 1994. Humans and mice with defects in the gene that codes for leptin, referred to as the obese or OB gene, tend to become morbidly obese.2 Obese mice with the ob/ob defect lose weight when treated with exogenous leptin.2 Leptin is produced primarily by white adipose tissue and blood levels correlated with body fat stores. Increased leptin levels stimulate the central nervous system to reduce appetite and increase energy expenditure. Leptin is thought to play an important role in the body’s response to food deprivation or starvation. Ongoing research indicates that leptin is also involved in a diverse array of physiologic functions beyond control of food intake and energy expenditure. A role for leptin has been implicated in the control of angiogenesis, hematopoiesis, immunity and bone formation, and a number of other functions. Leptin is thought to play a role in normal sexual development and in reproduction. Humans and mice with genetic absence of leptin fail to complete puberty and increased leptin levels in mice lead to early puberty. Studies also suggest that leptin levels affect fertility in females and may be involved in the development of normal pregnancy. During pregnancy, the placenta produces leptin, and maternal circulating levels during the second and third trimesters are approximately twice the level of the nonpregnant state.