Definition
A secondary adrenal cortex insufficiency is caused by a deficiency of the hormone ACTH (adrenocorticotropic hormone). This hormone is naturally produced in the pituitary gland and has a stimulating effect on the production of cortisol and the sex hormones, the so-called androgens. Pathological changes in the pituitary gland, also known as the adenohypophysis, can disturb the secretion of ACTH. As a result, the stimulating effect on the adrenal cortex does not occur and the body is undersupplied with cortisol and androgens.
Possible causes
The cause of secondary adrenal insufficiency is usually a tumorous change in the pituitary gland. This is part of the human brain and produces certain hormones, such as ACTH (Adrenocorticotrophic Hormone). The hormones of the adenohypophysis act as a messenger substance to other organs or tissues, as well as stimulating the adrenal cortex and stimulating it to produce the organ-specific hormones.
The secretion of ACTH normally leads to the secretion of cortisol and androgens in the adrenal cortex. If the effect of ACTH is absent, the adrenal cortex lacks the drive to produce these hormones. As a result, there is a deficiency of cortisol and androgens, which can manifest itself in a number of symptoms. The intake of cortisol, which is used as a drug in many diseases, can also lead to a reduced secretion of ACTH. Some authors speak of tertiary adrenal insufficiency in this context, which is why the external supply of cortisol should be neglected at this point as the cause of secondary adrenal insufficiency.
The diagnosis
The diagnosis of secondary adrenal insufficiency is based on a physical examination, blood values and special tests that allow the differentiation of adrenal insufficiency according to its cause. A secondary adrenal insufficiency generally shows a decreased cortisol level. ACTH (adrenocorticotropic hormone) levels in the blood are also lowered due to a dysfunction of the pituitary gland, resulting in a lack of hormone production.
Cortisol deficiency alone does not allow any conclusions to be drawn as to the cause of adrenal cortex insufficiency. The ACTH level in the blood and the result of the ACTH test are therefore decisive, especially for differentiation into a primary or secondary disorder. The ACTH test involves administering the hormone ACTH to the affected individuals, which leads to a slight increase in cortisol in the case of a secondary disorder. In primary insufficiency, on the other hand, such an effect usually does not occur.
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