Ata Ppgl Gi Symptom Management

Manage gastrointestinal symptoms from catecholamine excess in pheochromocytoma and paraganglioma

STEP 1 — Gather Information

Assess bowel movement frequency, stool consistency, abdominal distension, pain, nausea/vomiting; measure plasma-free metanephrines or 24‑hour urinary fractionated metanephrines/catecholamines; review blood pressure trends and abdominal imaging if obstruction suspected.

STEP 2 — Rule In / Rule Out

Rule out mechanical obstruction (e.g., adhesions, tumor mass) with CT abdomen/pelvis; if imaging shows no mechanical cause and catecholamines are markedly elevated, rule in catecholamine‑induced GI dysmotility.

STEP 3 — Classify or Stratify

Classify severity: mild constipation (≤3 stools/week), paralytic ileus (absent bowel sounds, distension), megacolon (colonic diameter >6 cm), or intestinal pseudo‑obstruction/perforation (signs of ischemia or free air).

STEP 4 — Decide

For mild constipation: start oral metyrosine 0.5 g/day, titrate to 2–3 g/day as needed; add IV phentolamine 5 mg bolus then infusion if oral inadequate. For ileus/pseudo‑obstruction: give IV phentolamine 1 mg/kg bolus followed by infusion 0.1–0.5 mg/kg/h plus oral metyrosine; if perforation suspected, obtain surgical consult immediately.

Clinical Guardrails / Mimics / Pitfalls

Avoid metoclopramide or domperidone (risk hypertensive crisis); selective α‑blockers (doxazosin) are ineffective for motility; monitor for hypotension and nausea during phentolamine; do not delay surgery if perforation signs appear.

Concrete Clinical Example

A 45‑year‑old with known SDHB‑related PPGL presents with 5‑day constipation, abdominal distension, and nausea. BP 150/95 mmHg, urinary normetanephrine 12× ULN. CT shows no mechanical obstruction. Start oral metyrosine 1 g/day and IV phentolamine infusion; after 12 hours, bowel movements resume and distension improves.

Source: Japan Endocrine Society Clinical Practice Guideline for the Diagnosis and Management of Pheochromocytoma and Paraganglioma 2025, Japan Endocrine Society, 2025, DOI: 10.1507/endocrj.EJ25-0165