Post-gastrectomy, a patient develops symptoms of early dumping syndrome: flushing, palpitations, diarrhea, and syncope 15–30 minutes after eating. What is the pathophysiological mechanism responsible for these symptoms?

• A Reactive hypoglycemia due to excess insulin secretion 2–3 hours post-meal
• B Bacterial overgrowth in the afferent limb causing bile salt deconjugation
• C Reduced gastric acid production causing malabsorption of fat-soluble vitamins
• D Rapid delivery of hyperosmolar chyme to jejunum causing fluid shift and vasoactive peptide release (GIP, VIP, glucagon) ✓

Explanation

Early dumping syndrome (15–30 min post-meal) is caused by rapid transit of hyperosmolar gastric contents into the jejunum, triggering massive fluid shift from the intravascular compartment into the gut lumen, causing hypovolemia, and stimulating release of vasoactive peptides including GIP, VIP, glucagon, neurotensin, and serotonin. These produce vasomotor symptoms (flushing, tachycardia, hypotension) and GI symptoms (nausea, diarrhea). Late dumping (2–3 hours post-meal) is due to reactive hypoglycemia from rapid glucose absorption followed by excessive insulin secretion. Afferent loop syndrome is a complication of Billroth II with bilious vomiting.

Reference: Bailey & Love's Short Practice of Surgery, 27th ed.

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