Leptin is a hormone produced primarily by the fat cells (adipocytes) and, to a lesser degree, by other tissues, including the placenta, in pregnant women.
After consuming enough food, this hormone tells the body that it is no longer hungry. In a normal feedback response, low levels of leptin trigger hunger and an increase in food consumption. As the level of leptin rises from an increase in fat cells, hunger decreases, and food consumption drops off.
Individuals with defects in the gene that codes for leptin tend to become morbidly obese. Leptin replacement therapy has been shown to be successful in treating some of those people affected by genetic alterations in the leptin gene.
Obesity is a significant health concern in the US because it increases the risk of several health conditions, such as hypertension, dyslipidemias, type 2 diabetes, joint problems, sleep apnea, coronary heart disease, stroke, and cancer. Obesity, associated with elevated leptin levels, is thought to be due to a resistance to leptin, similar to the insulin resistance often seen with obesity.
Leptin is involved in various functions beyond appetite control, satiety, and energy expenditure. Leptin has been implicated in the control of angiogenesis, immunity hematopoiesis, and bone formation. People with a genetic absence of Leptin fail to complete puberty, and it also affects fertility in women.
Dosage of leptin is usually ordered to help monitor patients in medical
weight loss therapy programs. Recent scientific evidence found that in some people, a leptin level might be more accurate than the traditional body mass index in estimating how much excess fat a person is carrying.
The amount of leptin in your blood is directly proportional to the amount of adipose tissue your body has. In other words, the less body fat, the less leptin you have, and the more body fat, the more leptin you have.
The dosage of leptin is sometimes ordered when a child has been classified as obese, especially when there is a family history of early-onset obesity.
Some physicians may order a leptin test when evaluating an obese person to determine whether they may have a leptin deficiency or an excess to detect resistance to leptin.
A blood sample is required for the test, and no fasting is required, although this test may be requested in conjunction with other tests that require fasting.
This is a single-marker test measuring leptin.