Leptin | Laboratory research

Leptin Irritated mediator between adipose tissue and hypothalamic-pituitary system. It is a protein encoded by the genome of fat cells, which predisposes to obesity.

Genetic deficiency of leptin (Whose synthesis is related to the Ob gene - obesity gene) causes pathological obesity, which can be treated with exogenous hormone.

Leptin is involved in the regulation of body weight and increases during weight gain. A 10% reduction in body weight results in a 53% reduction in leptin concentration. In contrast, a 10% weight gain increases blood serum leptin levels by 300%. Elevated leptin levels in such patients are explained by "leptin resistance", which is associated with a shift in hormone transport proteins or dysfunction of soluble leptin receptors.

Excess leptin leads to inhibition of insulin secretion, to the development of insulin resistance of skeletal muscle and adipose tissue, to a decrease in the action of insulin on liver cells, which leads to an increase in glycemia.

Leptin levels are associated with endocrine status. Its concentration is higher in women. This can be caused by different distribution of adipose tissue in women and men who have a more developed layer of subcutaneous fat, and depending on it, different rates of leptin synthesis.

High levels of leptin explain why vascular thrombosis develops - more often in overweight people during a stroke or heart attack than in people of normal weight. It has been shown that thrombus develops as a result of special interactions between leptin and platelet receptors. In general, leptin levels in the blood are associated with insulin and proinsulin levels.

Leptin levels reflect not only the amount of fat accumulated, but also changes in energy metabolism: it decreases during hunger, and even increases when food is consumed in excess. In practice, this is a signal of the body's adaptation to changing conditions of existence, the main aspect of which is the ability to switch from carbohydrates to fat metabolism during fasting (starvation).

There is a close association between hyperleptinemia and insulin resistance. Given the inhibitory effect of leptin on the development of obesity, it is believed that leptin production normally increases in response to an increase in insulin concentration, which prevents further production and release of insulin on the principle of negative feedback. Leptin levels are closely related not only to BMI (body mass index) but also to blood pressure levels, atherogenic lipoprotein concentrations, and insulin resistance index.

Decreased serum leptin levels can be caused by stress, intense physical exercise, and a long sedentary lifestyle. Metabolism declines, kilograms gain weight rapidly, and menstrual irregularities often occur in women - leading to infertility and osteoporosis.

Clinical studies have shown that leptin levels vary by race, it is lower in African-American women, which predisposes them to excess weight.

When to take a leptin test?

Adipose tissue secretory activity marker, additional marker of insulin resistance (with HOMA index):

• Suspicion of genetic leptin deficiency (obesity developed in early ASC);
• In the research complex of weight gain or weight problems;
• Impaired reproductive function in the face of reduced nutrition and excessive physical activity;
• In a set of studies to determine the risk factors for cardiovascular disease;
• Differential diagnostics of type 2 diabetes and obesity;
• Recurrent thrombosis.

How to prepare for the test?

The test is required on an empty stomach.

Research material

Venous blood

Possible interpretation of the results

Plasma leptin concentration is modulated by various physiological (restriction of food intake, exposure to cold) and hormonal factors (insulin, catecholamines, glucocorticoids, thyroid hormones, etc.).

Serum leptin levels decline rapidly in response to starvation and reflect profound changes in energy balance. Also, low levels of leptin lead to overeating, decreased secretion of the thyroid gland and reproductive hormones, and immunity.

Leptin levels are elevated:

• Obesity;
• Type 2 diabetes;
• More meals

Leptin levels are impaired:

• Hunger;
• Lose weight;
• Obesity associated with genetic leptin deficiency.