Hyponatremia is commonly observed during acute attacks of AIP. What is the mechanism?
- A Renal tubular acidosis from porphyrin deposition
- B SIADH secondary to autonomic dysfunction and neurotoxicity ✓
- C Adrenal insufficiency
- D Osmotic diuresis from glycosuria
Correct answer: B. SIADH secondary to autonomic dysfunction and neurotoxicity
Explanation
Hyponatremia in AIP is due to syndrome of inappropriate antidiuretic hormone secretion (SIADH), driven by autonomic and hypothalamic disturbance during acute attacks. It corrects with treatment of the porphyric attack. Renal tubular acidosis and adrenal insufficiency are not features. Glycosuria does not occur in AIP.
Reference: Harrison's Principles of Internal Medicine, 21st ed.
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