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Endocrine system diagnosis
Last reviewed: 05.07.2025
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The endocrine system includes endocrine glands that secrete the corresponding hormones into the blood. These glands include the pituitary gland, thyroid gland, parathyroid glands, islet apparatus of the pancreas, adrenal glands, including the cortex and medulla, testicles, ovaries, pineal gland, thymus gland. The endocrine system is functionally closely connected with the nervous system. Their interaction is achieved largely due to the hypothalamus, which produces hormones that enhance or inhibit the activity of the cells of the anterior pituitary gland, which in turn secrete the so-called tropic hormones that affect the function of the said endocrine glands.
It has now been established that, in addition to the endocrine glands, a number of other organs also contain cells that secrete hormonally active substances. Thus, the cells of the juxtaglomerular apparatus of the kidneys secrete renin, which participates in the formation of angiotensin. Erythropoietin is formed in the kidneys, which stimulates erythropoiesis. Neuroendocrine peptides - endorphins, etc. - are formed in the central nervous system. Natriuretic peptide is formed in the atria, which promotes the excretion of sodium and water by the kidneys. In the gastrointestinal tract, there are clusters of cells related to the so-called APUD system and forming polypeptide hormones that affect the function of the digestive system. The thymus gland produces hormonally active substances that participate in the differentiation of T-lymphocytes and the functioning of the immune system. Prostaglandins, thromboxane and prostacyclin, and a number of other substances are close to hormones in their meaning and role in the body.
Most hormones secreted by the endocrine glands circulate in combination with blood proteins (e.g., glucocorticosteroids, thyroid hormones) and exert their effects by binding to cellular receptors in target tissues.
Regulation of hormone secretion is based on a feedback system: if a hormone release changes the function of the corresponding target organ and as a result the internal environment of the body changes, then substances that inhibit hormone secretion begin to be produced. The hypothalamus-pituitary system takes a special part in this regulation: tropic hormones of the pituitary gland stimulate the function of other endocrine glands, hormones secreted by these glands suppress the secretion of hormones in the hypothalamus and pituitary gland. This regulatory system operates in a certain rhythm, which should be taken into account when assessing, for example, their content in the blood. The diversity of biologically active substances with different effects, features of regulation of their formation make the clinical manifestations of these effects extremely diverse, although many of them are quite characteristic of both states of increased and decreased production of hormonally active substances.
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