Adrenocorticotropic hormone in serum

Reference concentration values ​​of ACTH in serum: at 8.00 - less than 26 pmol / l, at 22.00 - less than 19 pmol / l.

ACTH - a peptide consisting of 39 amino acid residues with a molecular weight of about 4500. The secretion of ACTH in blood is exposed to circadian rhythms, the concentration is maximal at 6 a.m., and the minimum - about 22 hr strong stimulator of ACTH -. Stress. The half-life in the blood is 3-8 minutes.

Cushing's disease - one of the most severe and difficult it roendokrinnyh-hypothalamic-pituitary diseases genesis followed involving adrenal and forming a total of Cushing syndrome and related disorders of all types of exchange. Pathogenetic basis of Cushing's disease is a violation of feedback in the functional system of the hypothalamus-pituitary-adrenal cortex, characterized by constantly increased activity

pituitary hyperplasia kortikotrofov or, much more frequently, the development of ACTH-producing pituitary adenomas and hyperplasia of both adrenal cortex. In most cases, Itenko-Cushing's diseases show adenomas of the pituitary gland( macroadenomas in 5%, microadenomas in 80% of patients).

Iteco-Cushing's disease is characterized by a simultaneous increase in blood levels of ACTH and cortisol, as well as increased daily urinary excretion of free cortisol and 17-ACS.The determination of ACTH in the blood is necessary for differential diagnosis of the disease and various forms of the Itenko-Cushing syndrome( Table).The secretion of ACTH is significantly reduced in patients with corticosteroid and adrenal cortex cancer( Isenko-Cushing syndrome).In people with the disease and Cushing's syndrome, ectopic ACTH( ACTH secretion pathological tumor negipofizarnogo origin, often bronchus cancer or Timo-mine) ACTH concentration in the blood increased. For differential diagnosis between the last two diseases, a KRG test is used. With the Itenko-Cushing's disease, the secretion of ACTH after CRH administration is significantly increased. ACTH-producing tumor cells of non-hypophyseal localization have no CRH receptors, so the concentration of ACTH at this sample does not change significantly.

ectopic ACTH secretion syndrome often develops in lung cancer, carcinoid cancer and bronchus, malignant thymoma, primary carcinoids of the thymus and other tumors of the mediastinum. Less often, the syndrome accompanies tumors of the parotid glands, urinary and gallbladder, esophagus, stomach, colon, melanoma, and lymphosarcoma. Ectopic production of ACTH is also found in tumors of endocrine glands: cancer cells of the islets of Langerhans, medullary thyroid carcinoma, pheochromocytoma, neuroblastoma, ovarian cancer, testes, prostate gland. Due to the prolonged high concentration of ACTH, hyperplasia of the adrenal cortex develops in the blood and the secretion of cortisol increases. Table

differential diagnosis of Cushing

Table differential diagnosis of Cushing

concentration of ACTH in the blood may be from 22 to 220 pmol / L or more. In the diagnostic plan, in the syndrome of ectopic ACTH production, concentrations of ACTH in the blood above 44 pmol / L are considered clinically significant.

The best method for distinguishing the pituitary and ectopic sources ACTH is a simultaneous bilateral study of blood from the lower cavernous sinuses for ACTH.If the concentration of ACTH in the cavernous sinuses is significantly higher than in the peripheral blood, then the hypothyroid is the source of hypersecretion of ACTH.If the gradient between ACTH content in cavernous sinuses and peripheral blood is not traced, the source of increased hormone formation is most likely a carcinoid tumor of another localization.

Primary insufficiency of the adrenal cortex( Addison's disease).With primary adrenal insufficiency, as a result of destructive processes in the adrenal cortex, the production of HA, mineralocorticoids and androgens decreases, which leads to disruption of all types of metabolism in the body.

The most frequent laboratory signs of primary adrenal insufficiency are hyponatremia and hyperkalemia.

With primary adrenocortical insufficiency, the concentration of ACTH in the blood is significantly increased - by 2-3 times or more. Violation of the rhythm of secretion - the content of ACTH in the blood in both morning and evening is increased. With secondary adrenal insufficiency, the concentration of ACTH in the blood decreases. To assess the residual reserve of ACTH, a test with CRH is performed. If the pituitary gland is deficient, there is no reaction to CRH.When the process is localized in the hypothalamus( absence of CRH), the test can be positive, but the response of ACTH and cortisol to CRH administration is delayed. Primary adrenal insufficiency is characterized by a decrease in the concentration of aldosterone in the blood.

Secondary and tertiary adrenal insufficiency occurs as a result of brain damage, followed by a decrease in ACTH production and development of secondary hypoplasia or atrophy of the adrenal cortex. Usually, secondary adrenal insufficiency develops simultaneously with panhypopituitarism, but sometimes an isolated insufficiency of ACTH congenital or autoimmune is also possible. The most common cause of tertiary adrenal insufficiency is the long-term use of HA in high doses( treatment of inflammatory or rheumatic diseases).Suppressing the secretion of CRH with the subsequent development of adrenal insufficiency is a paradoxical consequence of the successful treatment of the Itenko-Cushing syndrome.

Nelson's syndrome develops after total removal of the adrenal glands with Isenko-Cushing's disease;is characterized by chronic supra-chewing insufficiency, hyperpigmentation of the skin, mucous membranes and the presence of a pituitary tumor. Nelson's syndrome is characterized by an increase in the concentration of ACTH in the blood. When conducting differential diagnosis between Nelson's syndrome and ectopic secretion of ACTH, it is necessary to conduct a simultaneous two-sided study of blood from the lower cavernous sinuses for ACTH, which allows us to clarify the localization of the process.

After surgical treatment( transsphenoidal operation with the removal of corticotropinoma), the determination of the concentration of ACTH in the blood plasma allows one to assess the radicality of the operation.

In pregnant women, the concentration of ACTH in the blood can be increased. The main diseases and conditions in which the concentration of ACTH can vary are given in Table.

Table Diseases and conditions in which the concentration of ACTH in the blood serum