Overview
Definition
A rare, chronic endocrine disorder in which the adrenal glands do not produce sufficient steroid hormones (glucocorticoids and often mineralocorticoids).
Epidemiology
Rare. Can present insidiously or as a life-threatening adrenal crisis.
Etiology & Risk Factors
- Autoimmune adrenalitis (most common cause in developed countries)
- Tuberculosis (most common cause worldwide)
- Metastatic cancer to adrenals
- Adrenal hemorrhage (e.g., Waterhouse-Friderichsen syndrome in meningococcemia)
Clinical Symptoms
- Profound fatigue and weakness
- Weight loss and anorexia
- Hyperpigmentation of skin and mucous membranes (due to excess ACTH/MSH)
- Orthostatic hypotension
- Salt craving
Clinical Approach
Diagnosis
- Morning Cortisol: Low
- ACTH level: Markedly elevated (lack of negative feedback)
- Cosyntropin (synthetic ACTH) Stimulation Test (Definitive): Cortisol fails to rise appropriately > 18 mcg/dL after 30-60 mins
- Basic Metabolic Panel: Hyponatremia, Hyperkalemia, Non-anion gap metabolic acidosis (due to aldosterone deficiency)
Management
- Glucocorticoid replacement: Hydrocortisone (often given 2-3 times daily to mimic circadian rhythm)
- Mineralocorticoid replacement: Fludrocortisone
- Stress dosing: Patients MUST double or triple their glucocorticoid dose during illness, surgery, or major stress to prevent crisis
Complications
- Adrenal Crisis (Addisonian Crisis): Life-threatening cardiovascular collapse, severe hypotension refractory to fluids, severe abdominal pain, and hypoglycemia. Requires IMMEDIATE IV hydrocortisone.