A peptide hormone secreted by the pituitary gland of vertebrates. It can promote the tissue proliferation of adrenal cortex and the production and secretion of corticosteroids.
The production and secretion of ACTH is directly regulated by the hypothalamic corticotropin releasing factor (CRF). Excessively secreted corticosteroids, in turn, can affect the pituitary and hypothalamus, reducing their activity. ACTH prepared from shark, frog, ostrich, mammalian pituitary are all thirty-nine peptides. The obvious structural difference is reflected in the carboxy-terminal region of the molecule (positions 25-33). The amino acid sequence of the amino terminal part (positions 1-24) is relatively consistent, and it is the central area of biological activity.
Secretory process
It is pulsed and strained, and the frequency and amplitude of release are related to the rhythm of alternating day and night. It can be used for anti-inflammatory and anti-allergy in medicine. Plasma adrenocorticotropic hormone (ACTH) is secreted by the pituitary gland and is a straight-chain polypeptide composed of 39 amino acids. The physiological role of ACTH is to promote adrenal hyperplasia, synthesis and secretion of adrenocortical hormones. The secretion of ACTH is controlled by the regulation of CRH in the hypothalamus. The determination of ACTH is mainly used for the etiological examination of Cushing disease caused by pituitary tumor or ectopic ACTH syndrome and the primary adrenal cortex.
Plasma ACTH is secreted in a pulsating manner, the highest from 8 am to 10 am. At night it is half of the morning. No such difference means abnormal
Reference
8 am 2.2 ～ 17.6pmol / L
6 pm 1.1 ～ 8.8pmol / L
Addison disease, congenital adrenal hyperplasia, ectopic ACTH syndrome, and ectopic CRH tumors can cause ACTH due to factors such as autoimmune, tuberculosis, fungal infections, tumors, leukemia, etc. Increase. Especially when heterologous ACTH syndrome. ACTH at midnight was significantly higher than the normal range, and the pattern of day and night disappeared.
Benign or malignant adrenal cortical tumors, double adrenal nodular hyperplasia or small nodular dysplasia, secondary to hypothalamic-pituitary lesions caused by ACTH deficiency caused by adrenal insufficiency can reduce ACTH.
ACTH measurement is mainly based on the radioimmunoassay method. There are extraction method and direct method. The latter method is simple but easy to be interfered by other substances. ACTH is extremely unstable, and is prone to degradation by proteases at room temperature. Blood samples should be anticoagulated with EDTA, and the plasma should be separated immediately and refrigerated. It can be stable for several months by freezing.
ACTH secretion function should be combined with other measurements, including: blood cortisol concentration and 17-OHCS.
Once the adrenocortical function test determines that the patient has hypercortisolism or adrenal hyperfunction, in order to determine the treatment plan, the etiology is clear, that is, whether it is primary hyperplasia of adrenal cortex or secondary to ACTH secreting tumor or hypothalamus When CRH is excessively secreted, the hypothalamic-pituitary-adrenal dynamic test is very important in this respect.
ACTH
Plasma adrenocortical hormone target = _blank> Adrenocorticotropic hormone This is an important test to judge the cause of adrenal cortical dysfunction, the location of the lesion and guide the treatment plan.
Plasma ACTH showed a circadian rhythm change within 24 hours, with the highest concentration at 8 am and the lowest concentration at 12 midnight. The ratio between the two was greater than 2. 8 am: 2.2 to 22.0 pmol / L (10 to 100 PG / ml) 12 midnight: 1.1 to 4.4 pmol / L (5 to 20 pg / mI)
- Increased physiology:
Stress conditions such as pain, mental stimulation, anger, and pregnancy can cause increased secretion.
- Pathological increase:
(1) Hypothalamus-pituitary dysfunction, increased ACTH secretion, such as pituitary adenoma, etc. At this time, plasma cortisol and urine free cortisol (UFC) also increase. (2) Primary adrenal insufficiency, such as Addison's disease, congenital adrenal hyperplasia, etc., because the level of cortisol in the body is too low, the pituitary gland stimulates compensatory secretion of ACTH increases. At this time, plasma cortisol and UFC reduce.
(3) The tissues other than the pituitary gland secrete heterologous ACTH, such as lung cancer, thymus cancer, pancreatic cancer and other cancer tissues. At this time, plasma ACTH, cortisol, and UFC are all elevated, and further hypothalamic-pituitary dysfunction needs to be assisted Identification.
(4) Non-specific increase, such as acute trauma, surgery, myocardial infarction and other stress states, generally lasts for a short time.
- Pathological reduction:
(1) Hypothalamus-pituitary dysfunction, reduced ACTH secretion, such as brain surgery, brain trauma, cerebral ischemic necrosis, intracranial tumor compression, radiotherapy, etc., resulting in decreased pituitary secretion function. At this time, plasma cortisol and UFC Also reduced.
(2) Primary cortisol syndrome caused by adrenocortical adenoma or cancer, due to excessive cortisol levels in the body, stimulates the pituitary gland to compensate for the decrease of ACTH. At this time, plasma cortisol and UFC will increase.
Same as "plasma cortisol".
Under stress conditions, such as burns, injuries, poisoning, and when an attack causes the body to respond to an alert response, ACTH secretion is increased, which immediately stimulates the release of adrenal cortex hormones and improves resistance.
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