Adrenal insufficiency is a general term for any condition in which plasma levels of cortisol are chronically lower than normal.
CORTISOL AND ALDOSTERONE ARE ESSENTIAL TO LIFE
Cortisol is one of the few hormones essential for life.
(The four hormones essential to life: insulin, parathyroid hormone, cortisol, and aldosterone: because these hormones are essential to life if you do not have them you die in few days)
In the absence of cortisol, a person would die rather quickly.
CAUSES OF ADRENOCORTICAL INSUFFICIENCY
Adrenocortical insufficiency can result from many causes:
- Primary adrenocortical insufficiency, also called Addison’s disease occurs due to loss of adrenal cortical function and all layers of the adrenal cortex undersecrete. The most common cause of this is autoimmune attack and consequent destruction of the cortex by production of adrenal cortex-attacking antibodies. In this condition, the immune system mistakenly recognizes the patient’s own adrenal cells as “foreign”. The resultant immune reaction causes the destruction of large portions of the adrenal gland.
Because of this, widespread destruction of the gland, all layers of the adrenal cortex undersecrete. Therefore, not only cortisol but also aldosterone levels is grossly inadequate in primary adrenocortical insufficiency.
Primary adrenocortical insufficiency may also occur when infectious diseases such as tuberculosis infiltrate the adrenal cortex and destroy the tissues. This is not very common, however.
Primary adrenocortical insufficiency from any of the causes is also called Addison’s disease, after the nineteenth the physician who first identified this syndrome.
2. Secondary adrenocortical insufficiency may occur because of a hypothalamic or pituitary defect, resulting in insufficient ACTH secretion.
THE DIFFERENCE BETWEEN PRIMARY AND SECONDARY ADRENOCORTICAL INSUFFICIENCY
Note that in Addison’s disease both cortisol and aldosterone are deficient, whereas in secondary form of the disorder, only cortisol is deficient, because aldosterone secretion is independent of ACTH stimulation.
SYMPTOMS OF ADRENOCORTICAL INSUFFICIENCY
Generally, the symptoms of adrenocortical insufficiency can be life threatening if not treated aggressively.
Symptoms associated with aldosterone deficiency, if severe enough, can be fatal because aldosterone is essential to life.
- The decrease in aldosterone concentration creates K+ retention (hyperkalemia) caused by reduced K+ excretion in the urine, and Na+ depletion (hyponatremia) caused by excessive urinary losses of Na+.
- The former disturbs cardiac rhythm (causing arrhythmia). The latter reduces ECF volume; the loss of salt and water balance can result in hypotension (lowered blood pressure).
Symptoms of cortisol deficiency are often less dramatic that those caused by aldosterone deficit. They include:
- poor response to stress
- hypoglycemia, caused by reduced gluconeogenic activity, and lack of permissiveness for many metabolic activities.
The secondary form of adrenocortical insufficiency is less threatening because aldosterone secretion, which is independent of the ACTH, is maintained by the renin-angiotensin system.