Cortisol

• Cortisol is secreted in a circadian rhythm. The highest levels are found early in the morning and the lowest around midnight.
• The material for testing is blood.
• The patient does not need to fast. It is recommended to drink a glass of water approximately 30 minutes before the examination.

Blood should be collected between 8:00 and 9:00 a.m., or as directed by your physician.
If the test is being performed after taking dexamethasone (an overnight dexamethasone suppression test),
a "post-dexamethasone cortisol" test should be ordered at registration.

A steroid hormone produced in the adrenal cortex that influences the metabolism of carbohydrates (increases gluconeogenesis and glycogenogenesis), fats (increases lipolysis), and proteins (increases their catabolism) and (to a lesser extent than aldosterone) water and electrolyte balance (increases sodium reabsorption in the renal tubules and promotes potassium excretion by the kidneys). It has anti-inflammatory and immunosuppressive effects, increases gastric acid secretion, causes calcium release from bones, triggers the release of bone marrow granulocyte reserves, and inhibits lymphocyte function. Cortisol constitutes 75-90% of the total amount of corticosteroids circulating in the blood. The production and secretion of glucocorticoids in the adrenal cortex is under the control of adrenocorticotropic hormone (ACTH), produced by the pituitary gland, and ACTH-releasing factor (CRF), produced by the hypothalamus. This regulation occurs through a negative feedback loop. Adrenal steroids circulate in the blood as protein binding sites, primarily transcortin and albumin. Steroid hormones are converted to biologically inactive metabolites in the liver.

It is also used as a medication in the treatment of certain chronic diseases (e.g., bronchial asthma) and as an emergency, short-term, or one-time treatment for life-threatening conditions (e.g., shock, status asthmaticus).

The importance of this test: diagnosing adrenal cortex dysfunction, searching for hormonally active (hormone-producing) tumors, and monitoring adrenal steroid therapy.

Abnormal values: in Cushing's syndrome and
Addison's disease. Secretory disorders cause adrenal hyperfunction or hypofunction.

Note: Under physiological conditions, this hormone is secreted in a circadian rhythm, with concentrations increasing in the morning and decreasing in the evening. It is a classic stress hormone.

A single result is for guidance only and cannot be used to diagnose a disease. Always consult your doctor.

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