What is leptin?

Leptin is a hormone produced by adipose tissue and the small intestine. Leptin’s primary function is to signal to the hypothalamus to remove the feeling of hunger when enough food has been consumed, though there are many other functions that have not yet been fully defined.

In healthy individuals an increase in fat will result in increased leptin, as it is produced by fat tissues. This normally results in a lower appetite, leading to weight loss. In individuals with reduced fat, leptin decreases and leads to increased hunger and weight gain.

Obesity changes this balance, as chronically high levels of leptin lead to reduced sensitivity and a higher leptin threshold to satiate hunger. Leptin deficiency results in intense, insatiable hunger. This condition is rare but has been implicated in childhood obesity and delayed puberty. These individuals require leptin injections to manage hunger.

Why take the test?

This test measures the level of leptin in the blood. It is typically used to diagnose leptin deficiency or monitor levels in obesity.