Addison's disease is caused by insufficient cortisol (and often aldosterone) production from the adrenal glands — usually from autoimmune destruction. It requires lifelong replacement with hydrocortisone and fludrocortisone. The most critical aspect of management is recognizing adrenal crisis — a life-threatening emergency — and knowing when to stress-dose.
Addison's disease (primary adrenal insufficiency) occurs when the adrenal glands are damaged and cannot produce enough cortisol — and often aldosterone. Without treatment it is fatal; with appropriate hormone replacement, most patients live normally. The key challenges are recognizing when to increase doses during illness and preventing adrenal crisis.
Causes
- Autoimmune adrenalitis (~80–90%): The immune system destroys the adrenal cortex — the same process as other autoimmune conditions. Often associated with other autoimmune diseases (Hashimoto's, Type 1 diabetes, celiac disease)
- Tuberculosis (historically leading cause worldwide)
- Bilateral adrenal hemorrhage (e.g., from meningococcal infection — Waterhouse-Friderichsen syndrome)
- Metastatic cancer to the adrenal glands
- Adrenoleukodystrophy (genetic; young males)
Signs & Symptoms
Symptoms develop slowly over months to years, often misattributed to depression or chronic fatigue:
- Fatigue and muscle weakness — the most universal complaint
- Hyperpigmentation — darkening of skin in sun-exposed areas, skin creases, scars, and mucous membranes; caused by elevated ACTH cross-reacting with melanocyte receptors
- Unintentional weight loss and decreased appetite
- Nausea, vomiting, abdominal pain
- Orthostatic hypotension — dizziness when standing (low aldosterone → sodium and fluid loss)
- Salt craving — the body attempts to compensate for sodium loss
- Hypoglycemia (low blood sugar)
- Low sodium, high potassium on blood tests
- Depression, irritability
🚨 Adrenal Crisis — Medical Emergency: Triggered by illness, surgery, trauma, or severe stress, adrenal crisis presents with severe weakness, confusion, vomiting, and cardiovascular collapse (very low blood pressure, shock). Treat immediately with hydrocortisone 100mg IV/IM and IV saline — do not wait for labs. Call 911. Every patient with Addison's disease should carry an emergency hydrocortisone injection kit.
Diagnosis
- Morning cortisol: Low cortisol (<3 mcg/dL virtually diagnostic; >18 mcg/dL rules out adrenal insufficiency)
- ACTH stimulation test (cosyntropin test): Gold standard — administer synthetic ACTH and measure cortisol at 0, 30, 60 minutes. Peak cortisol <18–20 mcg/dL = adrenal insufficiency
- ACTH level: Elevated in Addison's (primary) — distinguishes from secondary adrenal insufficiency (pituitary)
- Adrenal antibodies (21-hydroxylase Ab): Positive in autoimmune adrenalitis
- Electrolytes: low sodium, high potassium (from aldosterone deficiency)
Treatment
Hydrocortisone (15–25 mg/day in 2–3 divided doses) replaces cortisol. The largest dose is taken in the morning to mimic the natural diurnal rhythm. Fludrocortisone (0.05–0.2 mg/day) replaces aldosterone and is critical for blood pressure and sodium balance.
Stress Dosing Rules
| Situation | Action |
|---|---|
| Mild illness (fever <38.5°C, minor surgery) | Double usual hydrocortisone dose for duration of illness |
| Moderate illness (fever >38.5°C, vomiting, ER visit) | Triple dose or use IM emergency injection; seek medical care |
| Major surgery, unconscious, unable to take oral medications | IV hydrocortisone 100mg — inform anesthesia team in advance |
| Unable to keep oral medications down (vomiting) | Use emergency IM hydrocortisone injection immediately; call 911 |
Living Well with Addison's Disease
- Wear a medical alert bracelet at all times — "Adrenal Insufficiency — Needs Cortisol in Emergency"
- Carry an emergency hydrocortisone injection kit (Solu-Cortef Act-O-Vial or pre-filled syringe)
- Educate family members on how to administer emergency injection
- Provide all healthcare providers (dentist, surgeon, ER) with your diagnosis and steroid requirements
- Never run out of medication — refill before supplies deplete
Key Takeaways
- Addison's disease = adrenal insufficiency — insufficient cortisol and aldosterone production
- Most common cause is autoimmune destruction of the adrenal cortex (~80–90% of cases)
- Key symptoms: fatigue, hyperpigmentation, salt craving, low blood pressure, weight loss
- Adrenal crisis is a life-threatening emergency — treat with hydrocortisone 100mg IV/IM immediately
- Treatment: hydrocortisone (cortisol replacement) + fludrocortisone (aldosterone replacement) daily
- Stress dosing — double or triple dose during illness; IV steroids during surgery
- Always wear a medical alert bracelet and carry an emergency injection kit
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