Addison's disease, or primary adrenal insufficiency, is the inadequate production and release of hormones from the adrenal glands. The adrenal glands are found on top of both kidneys and are responsible for the production of epinephrine, norepinephrine, androgens, glucocorticoids and aldosterone. The adrenal glands help with electrolytes such as sodium and potassium.
Hypothalamic Regulation
The hypothalamic-pituitary-adrenal axis regulates the adrenal glands by negative feedback inhibition. The hypothalamic pituitary adrenal axis refers to the communication between the glans thaty involves the release of chemicals from the hypothalamus, which causes subsequent release of chemicals from the pituitary and eventually the adrenal glands. Negative feedback inhibition refers to the inhibition of the stimulus by an overproduced substance; for example, too much aldosterone inhibits hypothalamic stimulation of the pituitary.
Hypothalamic-Pituitary-Adrenal Axis or HPA axis
The hypothalamus stimulates the pituitary gland by producing CRH, or corticotropic releasing hormone. CRH causes the release of ACTH, or adrenocorticotropic hormone from the pituitary gland. ACTH stimulates the adrenal gland to produce and release glucocorticoids and aldosterone.
Aldosterone
Mineralocorticoids are a group of hormones that regulate sodium and potassium in the body. Aldosterone is the most important mineralocorticoids. Aldosterone stimulates the absorption of sodium and the excretion of potassium in the kidneys. Low blood sodium stimulates the HPA axis, which leads to the release of aldosterone from the adrenal glands and cause an increase retention of sodium in the kidneys.
Addison's Disease
Addison's disease is the destruction of the adrenal glands, preventing their response to ACTH. Lack of response to ACTH means reduced production of glucocorticoids and mineralocorticoids. In Addison's disease there is high ACTH, low sodium and high potassium in the blood. Low blood sodium also means that a person with Addison's disease will have a low blood pressure; when sodium is absorbed in the kidney, water is absorbed as well and therefore sodium absorption is important for maintaining blood pressure. Treatment for Addison's disease is intravenous administration of hydrocortisone and is authorized by a physician.
