In spite of its small size, the adrenal gland is a very important endocrine organ. The adrenal gland is composed of a cortex and a medulla. Both of which are actively engaged in hormones and neurotransmitters synthesis and secretion. The cortex of the adrenal gland secretes three known hormones. These hormones are androgens and corisol and aldosterone. The adrenal medulla is a nervous tissue analogue in which it synthesizes and secretes norepinephrine and epinephrine neurotransmitters. The difference between these two neurotransmitters as far as structure is concerned is by a methyl group which is attached to the amine group of epinephrine. Both of these hormones are secreted in the sympathetic part of the nervous system.
A disorder of the adrenal cortex is a congenital disease which is called congenital adrenal hyperplasia. In this congenital disease the adrenal cortex is unable to synthesize cortisol in sufficient amount due to a deficiency in specific enzymes in the cortisol synthetic pathway. This leads in turn to an increase in the secretion of adrenocorticotropic hormone or ACTH from the pituitary gland which in turn is supposed to stimulate the synthesis of more cortisol. Thus cortisol precursors accumulate due to their inability to be converted into cortisol. Instead they are converted into androgens. Therefore one of the clinical symptoms of this disorder is male pattern characteristics in females. The treatment to this disorder is supplements of cortisol in the diet.
Another disorder that the adrenal gland can have is cortisol excess in the blood or hypercortisolemia. This disorder can happen as a result of a pituitary adenoma in which the excess adrenocorticotropic hormone that is secreted by the pituitary stimulates the synthesis and secretion of excessive amount of cortisol. This disorder is called cushing syndrome. Another cause to cushing syndrome is adrenal cortex adenoma or adrenal cortex carcinoma, in which the gland oversecretes cortisol due to the tumor.
Excessive administration of cortisol in the diet which is used as an antiinflammatory agent, in addition to its use as an immune system suppressant can lead also to cushing syndrome.
Symptomes of cushing syndrome include among other things acne and hypertension. The hypertension is a direct result of cortisol effect on the body.
Another condition that is associated with adrenal hyperfunction is hyperaldosteronism or Conn's syndrome. This is a rare codition that is usually caused or triggered by an adenoma in the adrenal cortex. Aldosterone functions usually by stimulating the renal tubules of the kidney to reabsorb filtered sodium. Along with sodium is water reabsorbed by way of osmosis. Increased secretion of aldosterone or hyperaldosteronism leads to excessive conservation or reabsorption of sodium and water in the renal tubules. This leads clinically to accumulation of fluids (edema) in the body and hypertension. The treatment to this condition is the administration of diuretics or aldosterone antagonists.
The final disorder that we discuss here is a hyperfunction disorder of the adrenal medulla. In this case the secretion and synthesis of epinephrine and norepinephrine is excessive. Thus leading to a condition that is known clinically as pheochromocytoma. This condition can arise due to a malignant or benign tumor of the adrenal medulla. The clinical symptoms of this condition is hypertension without an apparent reason. The treatment is by surgery to remove the tumor or by antihypertensive drugs.