Somatotropic hormone (STH) or growth hormone has a polypeptide structure, is secreted by adenophypophysis and is stored in the granule of the gland. The secretion has a pulsating character and is accomplished under the action of physiological factors, increasing during stress, and decreasing significantly during sleep. The secretion is controlled by two hypothalamic hormones: the somatotropin releasing hormone and somatostatin or the somatotropin-releasing hormone inhibiting hormone. STH favors the growth of tissues and organs acting in relation to androgens and thyroid hormones, and stimulates cartilage proliferation with long bone growth. Insufficient STH secretion is usually congenital and is due to pituitary lesions or hypothalamus deficiency hormone deficiency. Lack of somatotropin is clinically translated into the child by pituitary nanosis.
Somatotropin hyper secretion occurs as a result of a pituitary tumor and manifests in the child by gigantism, and in the adult by acromegaly.
Human growth hormone (somatotropin) is essential in the growth process, and in adults it plays an important role in metabolic activities. It is synthesized in the acidophilic cells of the anterior pituitary, and its secretion from the intracellular storage granules is regulated by hormone-releasing hormone (GHRH) hormones and SRAT (somatotropin release-inhibiting factor). Its synthesis depends on neurotransmitters, such as serotonin, dopamine, norepinephrine, and growth hormone releasing peptides. It is also secreted in response to effort, stress, deep sleep, hypoglycemia, glucagon, insulin, thyroid hormones, estrogen, testosterone and vasopressin. In plasma, there are several monomeric and oligomeric isoforms (big GH and big big GH). The circulating GH-binding protein, which is similar to the extracellular domain of the tissue receptor of hGH.
HGH stimulates RNA production, protein synthesis, mobilizes fatty acids in stores and has transient antagonistic effects of insulin; elevated prolonged levels may induce alteration of glucose tolerance.
An excess of adult growth hormone will generate acromegaly.
A test is useful for confirming hypo- or hyperpituitarism, so that appropriate therapy can be initiated as soon as possible. Determination of the hormone can be performed under both basal and post stimulation conditions (physical exercise, arginine, glucagon or insulin) or suppression (after 100 g of glucose). A single determination of HGH has a limited value due to marked fluctuations in serum concentration. Stimulation or suppression tests provide much more information.
Elevated levels can be met postprandial after physical activity, deep sleep, stress, anxiety, sex hormone deficiency, especially androgens, increased levels of free fatty acids; low levels can occur in hunger, protein deficiency, metabolic unbalanced diabetes. These are some side effects, but of course there are no rare Somatropin side effects.