Cortisol in the blood

Reference values (norm) for serum cortisol concentration: at 8:00 a.m. - 200-700 nmol/l (70-250 ng/ml), at 8:00 p.m. - 55-250 nmol/l (20-90 ng/ml); the difference between morning and evening concentrations exceeds 100 nmol/l. During pregnancy, cortisol concentration increases, and the daily rhythm of its secretion is disrupted.

Cortisol is a steroid hormone secreted by the adrenal cortex. It accounts for 75-90% of the corticosteroids circulating in the blood and is metabolized in the liver. The half-life is 80-100 minutes. Cortisol is filtered in the renal glomeruli and excreted in the urine.

The concentration of cortisol in patients with chronic adrenal insufficiency is reduced. In primary and secondary adrenal insufficiency, the content of cortisol in the blood and free cortisol in the urine is also reduced. In individuals with moderate adrenal insufficiency, the concentration of cortisol in the blood may be normal due to a slowdown in the metabolism of the hormone. In this regard, in doubtful cases, it is necessary to conduct functional tests with ACTH preparations. In a healthy person, the concentration of cortisol in the blood after the introduction of these preparations increases by 2 times or more. The absence of a reaction to the introduction of ACTH indicates the presence of primary adrenal insufficiency.

In secondary adrenal insufficiency, the adrenal response to ACTH administration is preserved. It should be remembered that in long-term secondary adrenal insufficiency, adrenal cortex atrophy develops, and the glands lose the ability to increase glucocorticosteroid secretion in response to ACTH administration.

Blood cortisol is elevated in Cushing's disease and syndrome. Blood cortisol concentrations in Cushing's syndrome are usually elevated, but are subject to large fluctuations from day to day, so tests sometimes have to be repeated to confirm the diagnosis. In most patients, the normal daily rhythm of fluctuations in blood cortisol concentration is disrupted, but the most indicative concentrations are those determined at 8 a.m. and 8 p.m. In some patients with Cushing's disease and syndrome, blood cortisol concentrations are normal due to accelerated hormone metabolism or when testing is performed during the inactive phase of Cushing's disease. In such cases, dexamethasone tests are indicated. A decrease in cortisol during the test by 2 times or more compared to the background allows us to exclude Cushing's disease, while the absence of suppression of cortisol secretion by 50% or more confirms the diagnosis of this disease.

The syndrome of ectopic ACTH production is characterized by a significant increase in the rate of cortisol secretion compared to other forms of hypercorticism. If in Itsenko-Cushing's disease the rate of cortisol secretion is approximately 100 mg/day, then in ectopic tumors it reaches 200-300 mg/day.

The level of cortisol in the blood may be elevated in emotional people (reaction to venipuncture), with hypothyroidism, liver cirrhosis, terminal conditions, uncompensated diabetes mellitus, asthmatic conditions, and alcohol intoxication (in non-alcoholics).

An increased concentration of cortisol in the blood with the preservation of the daily rhythm of excretion is observed during stress, pain syndrome, fevers, Itsenko-Cushing syndrome.

An increase in the concentration of cortisol in the blood with the loss of the daily rhythm of excretion (the daily rhythm is monotonous) is observed in acute infections, meningitis, tumors of the central nervous system, acromegaly, right ventricular failure, liver failure, renal arterial hypertension, hyperfunction of the pituitary gland, depression, estrogen intake, etc.

A decrease in the concentration of cortisol in the blood is detected in primary hypofunction of the adrenal cortex, Addison's disease, and pituitary dysfunction.

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