Primary Adrenal Insufficiency (Addison's Disease)
The triad of hyperkalemia, paralytic ileus, and vomiting is most characteristically caused by primary adrenal insufficiency (Addison's disease), particularly during an adrenal crisis. 1
Pathophysiology
Primary adrenal insufficiency disrupts both glucocorticoid and mineralocorticoid production. The loss of aldosterone leads to:
- Hyperkalemia - Aldosterone normally promotes renal potassium excretion; its absence causes potassium retention 1
- Hyponatremia - Impaired sodium reabsorption
- Hypotension - Volume depletion from salt and water loss
The glucocorticoid deficiency and electrolyte disturbances directly cause gastrointestinal manifestations:
- Vomiting and nausea - Classic presenting symptoms 1
- Paralytic ileus - Hyperkalemia itself impairs intestinal motility 2, 3
- Abdominal pain - May mimic an acute abdomen during crisis 1
Clinical Recognition
According to the Endocrine Society guidelines, adrenal crisis presents with 1:
- Severe weakness and hypotension
- Marked acute abdominal symptoms (pain, nausea, vomiting, abdominal tenderness)
- Laboratory findings: hyponatremia, hyperkalemia, hypoglycemia
Critical pitfall: The combination of vomiting with hyperkalemia is counterintuitive since vomiting typically causes hypokalemia through GI losses. This paradoxical presentation should immediately raise suspicion for adrenal insufficiency 1.
Mechanism of Ileus
Hyperkalemia causes paralytic ileus through multiple mechanisms 2, 3:
- Direct neuromuscular effects causing generalized muscle weakness
- Impaired intestinal smooth muscle contractility
- GI symptoms manifest as nausea, vomiting, and paralytic ileus
Research demonstrates that severe hyperkalemia (>7-10 mEq/L) consistently produces gastrointestinal manifestations including paralytic ileus 2, 3.
Diagnostic Clues
Look for these specific features 1:
- Hyperpigmentation - Particularly in sun-exposed areas, skin creases, mucosal membranes (primary adrenal insufficiency only)
- Postural hypotension with marked drop
- Weight loss and chronic fatigue preceding acute presentation
- History of autoimmune disease (most common cause in Western countries)
Other Causes to Consider
While primary adrenal insufficiency is the classic cause, severe hyperkalemia from any etiology can produce this triad 2, 3:
- Potassium toxicity - Massive oral intake overwhelming renal excretion (rare with normal kidneys) 2
- Medication-induced - ACE inhibitors/ARBs with renal impairment 4
- Poisoning - Digoxin toxicity (inhibits Na+/K+ ATPase) 3
However, these alternative causes lack the characteristic hyperpigmentation and typically have clear exposure histories.
Immediate Management Priority
This is a medical emergency requiring 1:
- Immediate glucocorticoid replacement - Hydrocortisone 100mg IV bolus
- Volume resuscitation - Normal saline infusion
- Hyperkalemia treatment - Calcium gluconate for cardiac protection, insulin/glucose for potassium shift 2, 5
The hyperkalemia and ileus will resolve with correction of the underlying adrenal insufficiency - this distinguishes it from primary hyperkalemic causes where GI symptoms may persist 1, 6.