Adrenal Insufficiency

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Presentation :

• Characteristic findings include:
  • weight loss
  • fatigue, anorexia, nausea, vomiting, abdominal pain
  • orthostatic hypotension
  • hypoglycemia
  • eosinophilia
  • hyperpigmentation (primary adrenal insufficiency only)
  • hyponatremia and hyperkalemia (primary adrenal insufficiency only)
  • hypercalcemia

Pathophysiology :

• Primary: caused by adrenal failure
  • Results in loss of cortisol, aldosterone, and adrenal androgens
  • Autoimmune adrenalitis is the most common cause
• Secondary: caused by caused by impaired ACTH secretion by pituitary
  • Causes only cortisol and adrenal androgen deficiencies (aldosterone synthesis is not ACTH dependent)
  • Glucocorticoid use then withdrawal is the most common cause of secondary insufficiency

Diagnostic Testing:

• An 8:00 AM serum cortisol <3 μg/dL confirms cortisol deficiency and values >18 μg/dL exclude the diagnosis.
  • If cortisol deficiency confirmed use morning ACTH level to determine source of insufficiency
    • ACTH elevated (adrenal failure) => Adrenal CT
    • ACTH normal or suppressed => Pituitary MRI
  • If AM cortisol is intermediate use cosyntropin testing. Stimulated serum cortisol >18 μg/dL excludes adrenal insufficiency.

Treatment :

• Oral hydrocortisone 15 to 25 mg/d (standard dose)
• Oral fludrocortisone (primary adrenal insufficiency)
• Oral hydrocortisone 2 to 10 times standard dose during periods of physiologic stress, including minor surgery
• IV hydrocortisone 100 mg followed by 50 mg every 6 h for major stress (major surgery, trauma, critical illness, childbirth)
• Fludrocortisone is not required in primary adrenal insufficiency if the hydrocortisone dose >40 mg/d

Prognosis:

References: