Introduction: Vasoactive intestinal peptide (VIP) is a neuropeptide hormone that plays a role in regulating gastric acid secretion and vasodilation. Elevated VIP levels can present as: watery diarrhea, hypokalemia, and achlorhydria (WDHA). Elevated VIP is seen in pancreatic tumors, specifically VIP-omas, and rarely pheochromocytomas.
There are less than 30 case reports of pheochromocytoma secreting VIP. Prompt identification and management of pheochromocytoma secreting VIP includes timely identification of electrolyte derangements, a careful history, and prompt imaging and laboratory data.
Description: A 58-year-old female was admitted to the Intensive Care Unit (ICU) with watery diarrhea, hyponatremia (Na+ 104), witnessed seizure event, and hypokalemia. Prior to admission, the patient experienced fourteen daily episodes of secretory diarrhea consistent with watery stool for the past 2 weeks. Stool tests were negative for infection. CT abdomen and pelvis revealed a 6.7 x 5.4 x 6.8 cm heterogenous well-circumscribed left adrenal mass. Laboratory work-up was significant for 24 hour urine metanephrine and normetanephrine levels of 8988 ug/L and 1452 ug/L, respectively. Aldosterone/renin, thyroid, and calcitonin levels were within normal limits. Gastrin level was mildly elevated but thought to be elevated due to pantoprazole. Serum VIP was found to be elevated at 206 pg/mL. The patient underwent appropriate sodium correction and was subsequently started on alpha and then beta blockade. Her diarrhea had minimal response to loperamide throughout hospitalization, but began to resolve autonomously during blockade. She declined trial of octreotide. Perioperative management was uneventful, and the patient successfully underwent adrenalectomy without complication. At one week follow-up patient had complete resolution of diarrhea.
Discussion: Classic manifestations of a pheochromocytoma include episodic hypertension, headaches, palpitations, diaphoresis, and sweating in response to the release of catecholamines. The overshadowing vasodilatory effects of VIP resulting in excessive volume depletion likely counteracted the catecholamine surg that is often associated with pheochromocytomas, delaying diagnosis. Electrolyte derangements, alpha and beta blockade, and perioperative course should be managed in the ICU.
