Adrenal Disorders: Addison's Disease and Cushing's Syndrome

The adrenal glands produce cortisol, aldosterone, and androgens, which regulate metabolism, fluid balance, and the stress response. Addison's disease is adrenal insufficiency (too little hormone), while Cushing's syndrome is adrenal excess (too much hormone). Recognizing the opposite patterns of these two disorders is high-yield for nursing exams and safe clinical practice.

Addison's vs Cushing's: Quick Comparison

• Cortisol: Addison's low / Cushing's high
• Aldosterone: Addison's low / Cushing's normal or high
• Blood pressure: Addison's hypotension / Cushing's hypertension
• Sodium: Addison's low (hyponatremia) / Cushing's high or normal
• Potassium: Addison's high (hyperkalemia) / Cushing's low (hypokalemia)
• Blood sugar: Addison's low (hypoglycemia) / Cushing's high (hyperglycemia)
• Weight: Addison's weight loss / Cushing's weight gain with central obesity
• Skin: Addison's hyperpigmentation / Cushing's purple striae, easy bruising
• Fat distribution: Cushing's shows moon face and buffalo hump
• Energy: Both cause fatigue; Cushing's also causes muscle wasting

Memory trick: Addison's is "all down" (low cortisol, sodium, BP, sugar). Cushing's is "all up" (high cortisol, BP, sugar).

Addison's Disease (Adrenal Insufficiency)

Addison's disease is primary adrenal insufficiency caused by destruction of the adrenal cortex, leading to deficient cortisol and aldosterone. It is life-threatening without treatment.

Causes

• Autoimmune destruction — most common, 70–80% of cases
• Tuberculosis — historically the leading cause; still common in developing countries
• Adrenal hemorrhage from sepsis, trauma, or anticoagulants
• Metastatic cancer involving the adrenal glands
• Surgical removal of adrenal glands
• Sudden withdrawal of long-term steroids (secondary adrenal insufficiency)

Signs and Symptoms

• Chronic fatigue and weakness (early and persistent)
• Weight loss and anorexia
• Hyperpigmentation — hallmark sign in primary Addison's (skin creases, scars, gums, pressure points)
• Hypotension, often orthostatic
• Hyponatremia and hyperkalemia from aldosterone deficiency
• Hypoglycemia from cortisol deficiency
• Salt craving
• Nausea, vomiting, diarrhea

Diagnosis

• Cosyntropin (ACTH) stimulation test — gold standard; in Addison's, cortisol does not rise appropriately after synthetic ACTH
• Electrolytes: hyponatremia, hyperkalemia, hypoglycemia

Treatment

• Hydrocortisone to replace cortisol
• Fludrocortisone to replace aldosterone
• Lifelong hormone replacement
• Stress dosing — double or triple the dose during illness, surgery, or trauma

Addisonian Crisis (Emergency)

Addisonian crisis is life-threatening acute adrenal insufficiency, often precipitated by infection, trauma, surgery, or stress.

• Signs: severe hypotension, shock, hyponatremia, hyperkalemia, hypoglycemia
• Assess ABCs and secure airway first
• Administer IV hydrocortisone immediately
• Give IV normal saline for hypotension
• Monitor potassium and glucose closely

Nursing Priorities and Patient Teaching

• Monitor blood pressure, weight, and electrolytes
• Teach strict medication adherence — never skip doses
• Teach stress dosing during illness, surgery, or trauma
• Wear medical alert identification
• Report weakness, dizziness, vomiting, or confusion (crisis signs)

Cushing's Syndrome (Adrenal Excess)

Cushing's syndrome results from chronic exposure to excess cortisol. It may be endogenous (body overproduces) or exogenous (steroid medications — the most common cause).

Causes

• Exogenous steroids (e.g., long-term prednisone) — most common
• Pituitary adenoma (Cushing's disease) — excess ACTH stimulates the adrenals
• Adrenal adenoma or carcinoma — autonomous cortisol production
• Ectopic ACTH production (e.g., small cell lung cancer)

Signs and Symptoms

• Central obesity with truncal weight gain and thin extremities
• Moon face (rounded, red, full)
• Buffalo hump (fat pad on upper back)
• Purple striae on abdomen, thighs, breasts
• Thin, fragile skin; easy bruising
• Poor wound healing; recurrent infections
• Hypertension from sodium and water retention
• Hyperglycemia / diabetes mellitus
• Hypokalemia
• Osteoporosis and fractures
• Muscle wasting and weakness
• Mood changes (depression, irritability, psychosis)
• Hirsutism and menstrual irregularities in women

Diagnostic Tests

• 24-hour urinary free cortisol — measures cortisol excretion
• Dexamethasone suppression test — in Cushing's, cortisol remains high
• Midnight salivary cortisol — elevated

Treatment

• If steroid-induced: taper gradually — never stop abruptly
• Surgical removal of pituitary or adrenal tumors
• Radiation therapy for pituitary tumors
• Cortisol-blocking medications (ketoconazole, metyrapone)

Nursing Priorities and Patient Teaching

• Monitor blood pressure and blood glucose
• Provide skin care to prevent breakdown
• Protect from infection (immunosuppression)
• Provide emotional support for body image changes
• Never stop steroids abruptly — taper as directed
• Monitor BP and blood sugar at home; report infection signs promptly

Lab Findings at a Glance

• Serum sodium: Addison's low / Cushing's normal or high
• Serum potassium: Addison's high / Cushing's low
• Blood glucose: Addison's low / Cushing's high
• Serum cortisol: Addison's low / Cushing's high
• ACTH: Addison's high (primary) / Cushing's low or high depending on cause

Common Exam Traps

• Addison's → hyperpigmentation; Cushing's → purple striae
• Addison's → hypotension; Cushing's → hypertension
• Addison's → hyponatremia + hyperkalemia; Cushing's → hypernatremia + hypokalemia
• Exogenous steroids are the most common cause of Cushing's
• Autoimmune destruction is the most common cause of Addison's
• Addisonian crisis → IV hydrocortisone first
• In Cushing's, never stop steroids abruptly — taper slowly

Key Takeaways

• Addison's = adrenal insufficiency (low cortisol/aldosterone); Cushing's = adrenal excess (high cortisol).
• Addison's is treated with lifelong hydrocortisone and fludrocortisone, with stress dosing during illness, surgery, or trauma.
• Addisonian crisis is an emergency: ABCs, IV hydrocortisone, and IV normal saline.
• Cushing's is most often caused by exogenous steroids; manage by tapering steroids or removing tumors — never stop steroids abruptly.
• Remember the opposite electrolyte and vital sign patterns: Addison's = low Na, high K, low BP, low glucose; Cushing's = high Na, low K, high BP, high glucose.
• Nursing priorities for both: monitor electrolytes, BP, and glucose; ensure medication adherence; and confirm patients wear medical alert identification.