Reference values (norm) of cortisol concentration in blood serum: at 8.00 - 200-700 nmol / l (70-250 ng / ml), at 20.00 - 55-250 nmol / l (20-90 ng / ml); the difference between the morning and evening concentrations exceeds 100 nmol / l. During pregnancy, the concentration of cortisol increases, the daily rhythm of its excretion is disturbed.
Cortisol is a steroid hormone secreted by the adrenal cortex. It is 75-90% of the corticosteroids circulating in the blood, is metabolized in the liver. The half-life is 80-100 min. Cortisol is filtered in the renal glomeruli and is removed with urine.
The concentration of cortisol in patients with chronic insufficiency of the adrenal cortex is reduced. With primary and secondary adrenal insufficiency, the content of cortisol in the blood and free cortisol in the urine is also reduced. In people with moderate adrenal insufficiency, the concentration of cortisol in the blood can be normal due to a slowing of the metabolism of the hormone. In this regard, in doubtful cases, it is necessary to carry out functional tests with ACTH preparations. In a healthy person, the concentration of cortisol in the blood after the administration of these drugs increases by 2 times or more. The lack of response to the introduction of ACTH testifies to the presence of primary adrenal insufficiency.
With secondary adrenal insufficiency, the adrenal response to the introduction of ACTH is preserved. It should be remembered that with long-lasting secondary adrenal insufficiency, adrenocortical atrophy develops, and they lose the ability to increase the secretion of glucocorticosteroids in response to the introduction of ACTH.
Cortisol in the blood is elevated in case of illness and Isenko-Cushing syndrome. The concentration of cortisol in the blood with Isenko-Cushing syndrome is usually increased, but is subject to large fluctuations from day to day, so to confirm the diagnosis, sometimes you have to repeat the research. In most patients, the normal daily rhythm of fluctuations in the concentration of cortisol in the blood is disturbed, but the concentrations at 8 and 20 hours are most indicative. In some patients with Isenko-Cushing's disease and syndrome, the concentration of cortisol in the blood is normal because of the acceleration of hormone metabolism or Research during the inactive phase of the Itenko-Cushing disease. In such cases, dexamethasone tests are indicated. Reduction of cortisol in a sample 2 times or more in comparison with the background allows excluding the Itenko-Cushing's disease, whereas the absence of inhibition of the secretion of cortisol by 50% or more confirms the diagnosis of this disease.
For the syndrome of ectopic ectopic production of ACTH, a significant increase in the secretion rate of cortisol is characteristic in comparison with other forms of hypercorticism. If the rate of secretion of cortisol is approximately 100 mg / day in the course of the Itenko-Cushing's disease, then at ectopic tumors it reaches 200-300 mg / day.
The content of cortisol in the blood can be increased in emotional people (reaction to the vein puncture), hypothyroidism, liver cirrhosis, terminal conditions, uncompensated diabetes mellitus, asthmatic conditions, alcohol intoxication (in non-alcoholics).
Elevated concentration of cortisol in the blood with preservation of the daily rhythm of excretion is observed under stress, pain syndrome, fevers, Isenko-Cushing syndrome.
An increase in the concentration of cortisol in the blood with the loss of the daily rhythm of excretion (daily rhythm monotonous) is noted in acute infections, meningitis, CNS tumors, acromegaly, right ventricular failure, liver failure, renal arterial hypertension, pituitary hyperphysia, depression, estrogen administration, etc.
Reducing the concentration of cortisol in the blood is revealed with primary hypofunction of the adrenal cortex, Addison's disease, impaired functions of the pituitary gland.
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