About Cortisol Lab Test

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Cortisol is a steroid hormone that is produced in the cortex of the adrenal glands located on top of each kidney. Fasting, food intake, exercising, awakening, and psychosocial stress cause the body to release cortisol. It is released in a highly irregular manner with peak secretion in the early morning, which then tapers out in the late afternoon and evening. Following ACTH binding to cells of the adrenal cortex, cortisol is synthesized and released into the bloodstream. Up to 95% of the secreted cortisol will be bound to large proteins and carried throughout the body in the blood. Since the vast majority of cortisol actions rely on binding to its cytosolic mineralocorticoid and glucocorticoid receptors, only the small fraction of unbound, i.e., free cortisol is thought to be biologically active. Due to its low molecular weight and lipophilic nature, unbound cortisol enters cells by passive diffusion which makes it feasible to measure the free cortisol fraction in all bodily fluids.

Under stressful conditions, cortisol can utilize protein for energy production through gluconeogenesis, the process of converting amino acids into carbohydrate in the liver. Additionally, it can move fat from storage depots and relocate it to fat cell deposits deep in the abdomen. Cortisol also aids adipocytes to grow up into mature fat cells. Finally, cortisol may act as an anti-inflammatory agent, suppressing the immune system during times of physical and psychological stress.

Elevated levels observed in:-

Adrenal tumor

Cushing's syndrome

ectopic ACTH-producing tumors

Diabetes mellitus

Glucocorticoid resistance

Decreased levels observed in:-

Addison's disease