The adrenal gland synthesizes steroid hormones in
the cortex and catecholamines in the medulla. Adrenal
insufficiency refers to a state of deficiency
of adrenal gland hormone production in the cortex. It affects about
1 to 4 people per 100,000 in the U.S.1
Adrenal crisis is a life-threatening exacerbation
of adrenal insufficiency due to increased physiologic demand (e.g.,
infection) or decreased supply (e.g., discontinuation of steroid
therapy) of cortisol. It usually occurs in response to a major stress,
such as acute myocardial infarction, sepsis, surgery, major injury,
trauma, or other illnesses in any patient with primary or secondary
adrenal insufficiency. In this situation, the adrenal gland fails
to mount a stress response via increasing circulating cortisol levels.
The most frequent iatrogenic cause of acute adrenal crisis
is rapid withdrawal of steroids in patients with adrenal atrophy
secondary to long-term steroid administration. About 20% of
acquired immunodeficiency syndrome patients eventually develop adrenal
insufficiency.2,3 Currently, patients
with major head trauma develop pituitary insufficiency much more
frequently than previously recognized.4 Head trauma affects
adrenocorticotropic hormone (ACTH) production, which decreases secretion
of cortisol from the adrenal gland.
Primary adrenal insufficiency, or Addison disease,
is due to intrinsic adrenal gland dysfunction and results
in decreased cortisol and aldosterone production. Approximately
90% of the gland must be destroyed for clinical adrenal
insufficiency to develop.5 The
causes include infection [e.g., tuberculosis, human immunodeficiency
virus (HIV)], drugs, adrenal hemorrhage (from use of warfarin,
sepsis, and trauma), sarcoidosis, autoimmune disorders,
metastases, and congenital adrenal hyperplasia.
Secondary adrenal insufficiency is due to
hypothalamic-pituitary dysfunction causing inadequate ACTH production.
This results in cortisol deficiency only. This may be
caused by withdrawal of prolonged steroid therapy, pituitary disease,
head trauma, or postpartum pituitary necrosis (Sheehan syndrome).
The adrenal gland is made up of the cortex (outer layer) and
medulla (inner layer) producing steroid hormones and catecholamines,
respectively. The adrenal cortex produces three categories of steroids.
These include the glucocorticoids (cortisol),
mineralocorticoid (aldosterone), and gonadocorticoids
(sex hormones: testosterone and estrogen).
Glucocorticoids are produced from the zona glomerulosa, whereas
the latter two groups of steroids are produced from both the zona
fasciculata and zona reticularis.
Cortisolis secreted from the cortex of
the adrenal gland in response to direct stimulation by ACTH. ACTH
secretion is stimulated by the hormone corticotropin-releasing factor
released from the hypothalamus. This occurs in a diurnal rhythm,
with higher levels secreted in the morning and lower levels in the
evening. Plasma cortisol suppresses the release of ACTH by negative
feedback inhibition. Cortisol facilitates the patient’s
stress response, affecting the heart, vascular bed, water excretion, electrolyte
balance, potentiation of catecholamine action, and control
of water distribution. It affects
the fat, protein, and carbohydrate metabolism by producing the glucose
by glycogenolysis and neoglycogenesis. It is involved in immunologic
and inflammatory responses and affects calcium metabolism. It ...