Addison's Disease vs Cushing's Syndrome
Addison's Disease vs Cushing's Syndrome
Addison's disease and Cushing's syndrome are opposite adrenal disorders that are frequently compared on the NCLEX. Addison's involves insufficient cortisol production (adrenal insufficiency), while Cushing's involves excessive cortisol (hypercortisolism). Their clinical presentations are mirror images of each other, making this comparison a high-yield NCLEX topic.
Comparison Table
Key Differences
- →Addison's is cortisol DEFICIENCY (hypoadrenalism); Cushing's is cortisol EXCESS (hypercortisolism); they are exact opposites
- →Addison's causes hypotension, hypoglycemia, hyperkalemia, and bronze skin; Cushing's causes hypertension, hyperglycemia, hypokalemia, and moon face with buffalo hump
- →Addisonian crisis is a life-threatening emergency triggered by stress, infection, or abrupt steroid withdrawal; it presents with severe hypotension, dehydration, and shock
- →The most common cause of Cushing's syndrome is iatrogenic (exogenous corticosteroid use such as chronic prednisone therapy)
Clinical Relevance
- •Never abruptly discontinue corticosteroids in patients on long-term therapy because it can precipitate Addisonian crisis due to suppressed adrenal function; always taper the dose
- •Teach Addison's patients to wear a medical alert bracelet and increase steroid doses during illness or stress to prevent adrenal crisis
- •Cushing's patients are immunosuppressed due to excess cortisol and are at high risk for infection; monitor for subtle signs because the inflammatory response is blunted
Study Tips
- ✓Think of Addison's as everything is DOWN (cortisol, BP, glucose, sodium) except potassium; Cushing's is everything is UP (cortisol, BP, glucose, sodium) except potassium
- ✓Memory aid: Addison's = Add steroids (the patient needs cortisol replacement); Cushing's = Cushion-like body (moon face, buffalo hump, truncal obesity)
- ✓For NCLEX, if you see bronze skin with hypotension and hyperkalemia, choose Addison's; if you see moon face with hypertension and hyperglycemia, choose Cushing's
FAQs
Common questions about this comparison
Addisonian crisis (acute adrenal crisis) is a life-threatening emergency caused by a sudden drop in cortisol, usually triggered by stress, illness, surgery, or abrupt withdrawal of corticosteroids. It presents with severe hypotension, dehydration, hyponatremia, hyperkalemia, hypoglycemia, and shock. Nursing interventions include IV fluid resuscitation with normal saline, IV hydrocortisone (Solu-Cortef) 100 mg bolus, correction of hypoglycemia with D50, continuous cardiac monitoring for hyperkalemia, and vasopressors if needed.
Long-term exogenous corticosteroid use suppresses the hypothalamic-pituitary-adrenal (HPA) axis through negative feedback. The adrenal glands atrophy and stop producing cortisol naturally. If steroids are suddenly stopped, the adrenals cannot immediately resume cortisol production, resulting in acute adrenal insufficiency (Addisonian crisis). Steroids must always be tapered gradually to allow the HPA axis to recover.