Adrenal disorders

Clinical information

The function of the adrenal cortex is to synthesise numerous steroid hormones. These are divided into glucocorticoids (e.g. cortisol), mineralocorticoids (e.g. aldosterone) and sex hormones (e.g. androgens). The amount and timing of the hormone production is primarily regulated by the adrenocorticotropic hormone (ACTH). ACTH in turn is controlled by the corticotropin-releasing hormone (CRH).

Synthesis of aldosterone, the main regulator of salt and water in the body, is also controlled by the amount of sodium and potassium in the blood and by the renin-angiotensin-aldosterone system (RAAS).

Hormone production in the adrenal cortex can be impaired by different diseases, resulting in a hormone over- or underproduction. This leads to hypo- or hyperfunction of different organs and to various diseases.

Diagnostics

Hyperfunction of the adrenal cortex is associated with Conn’s syndrome, Cushing’s syndrome and adrenogenital syndrome.

Chronic cortisol excess leads to Cushing’s syndrome. It can be caused by ACTH overproduction due to a tumour in the pituitary gland or by cortisol overproduction due to a tumour in the adrenal gland. Cushing’s syndrome can also be caused by an excess of cortisol-like components from medication. Cortisol measurements in blood, saliva or urine and a dexamethasone suppression test are recommended for Cushing’s syndrome diagnostics.

Aldosterone overproduction results in hyperaldosteronism. The most common symptom is high blood pressure. Up to ten percent of all cases of hypertension are caused by primary hyperaldosteronism (Conn’s syndrome). In Conn’s syndrome, the renin concentration is simultaneously decreased, while the secondary form of hyperaldosteronism is a result of overstimulation of the RAAS. It is recommended to determine the aldosterone-renin concentration in suspected cases of hyperaldosteronism.

In adrenogenital syndrome, cortisol production is impaired by congenital enzyme defects. Increased amounts of cortisol precursors (e.g. 17-OH progesterone) are produced, but not the functional hormone. Due to the lack of negative feedback, the accumulation of precursors leads to increased production of androgens.

Hypofunction of the adrenal cortex causes adrenal cortex insufficiency. The most frequent cause of primary adrenal cortex insufficiency is Addison’s disease. Because of the autoimmune-induced destruction of hormone-producing cells of the adrenal cortex (autoantibodies against adrenal cortex), it can no longer synthesise hormones. Diagnostics is based on the combined measurement of cortisol and ACTH.