Cortisol | Laboratory research

Cortisol An important glucocorticosteroid that is essential for the many functions of the body. Like other glucocorticosteroids, cortisol is synthesized in the area of ​​the adrenal cortex. In the blood, 90% of cortisol is bound to corticosteroid-binding protein (CBG) and albumin. Only a small fraction of cortisol circulates freely and can interact with receptors.

The most important physiological functions of cortisol are - increase in blood glucose levels (by stimulating gluconeogenesis), anti-inflammatory and immunosuppressive action.

Cortisol synthesis and secretion are controlled by negative feedback mechanisms of the hypothalamic-pituitary-adrenal gland. If cortisol levels are low, corticotropin-releasing hormone (CRH) is secreted by the hypothalamus, causing the pituitary gland to release ACTH. ACTH stimulates cortisol synthesis and secretion in the adrenal cortex. Cortisol itself acts on the pituitary gland and hypothalamus through a negative feedback mechanism. In addition, stress increases cortisol secretion.

Normally, serum cortisol concentrations experience daily variability. The maximum concentration (up to 700 nmol / l) is observed in the morning, and the lowest concentration (which is about half of the morning) - 16:00 - 20:00. It is therefore essential to know the timing of the test in order to interpret the results.

Stimulation or inhibition tests may also be performed. Dexamethasone inhibition test (2 variants: 1 mg or 8 mg) is used to determine the cause of the increase in basal cortisol levels.

When should we take a cortisol test?

This test is always prescribed on the recommendation of a doctor, taking into account your condition.

• To assess the level of activity of the hypothalamic-pituitary-adrenal system;
• Itzenko-Cushing Syndrome - Numerous and progressive symptoms of the disease (obesity, hypertension, hyperglycemia, myopathy, hirsutism, plethora, osteoporosis, pathological fractures, red stretch marks, cutaneous and soft tissues of the skin).
• Atypical clinical symptoms for the patient's age (osteoporosis, arterial hypertension);
• Children with growth retardation and overweight;
• Adrenal incidentaloma, with visual signs of adenoma;
• Differential diagnostics of primary and secondary adrenal insufficiency in conjunction with an ACTH study.

How to prepare for the test?

Venous blood is required for analysis.

The test is done on an empty stomach from 7 a.m. to 10 p.m.

Possible interpretation of the results:

Elevated cortisol levels:

• Itzenko-Cushing disease / syndrome;
• Adrenal hyperplasia;
• Ectopic CRH syndrome (corticotropin-releasing hormone);
• Ectopic ACTH syndrome;
• Polycystic ovary syndrome;
• Hypothyroidism (decreased catabolism);
• Hyperthyroidism;
• Hypoglycemia;
• Obesity;
• Depression;
• HIV infection (in adults);
• Cirrhosis of the liver (decreased catabolism);
• Decompensated diabetes mellitus;
• Alcoholism;
• Pregnancy

Decreased cortisol levels:

• Hypopituitarism;
• Addison's disease;
• Condition after taking glucocorticoids;
• Adrenogenital syndrome;
• Hypothyroidism (decreased secretion);
• Liver failure - decreased secretion (cirrhosis, hepatitis);
• Sharp weight loss.