When hypertensive crisis mimics septic shock: A case report of pheochromocytoma-induced severe lactic acidosis following GLP-1 receptor agonist administration

Rationale: Pheochromocytoma is a rare catecholamine-secreting tumor that may present atypically with severe lactic acidosis and systemic inflammatory features, closely mimicking sepsis and delaying diagnosis. A possible interaction with glucagon-like peptide-1 (GLP-1) receptor agonists has been suggested but remains poorly understood. Patient concerns: A 48-year-old woman with type 2 diabetes mellitus presented with acute nausea, vomiting, chills, severe abdominal pain, and hypertensive crisis within hours of self-administering tirzepatide, a dual GLP-1/glucose-dependent insulinotropic polypeptide receptor agonist. She was febrile, tachycardic, and markedly hypertensive, with severe lactic acidosis and systemic inflammatory markers suggestive of sepsis. Diagnoses: Initial evaluation favored sepsis; however, negative cultures, sustained severe hypertension, hyperlactatemia disproportionate to perfusion status, and elevated urinary normetanephrines redirected the evaluation toward an endocrine cause. The clinical and biochemical picture supported a diagnosis of probable pheochromocytoma. Imaging revealed a fat-containing left adrenal mass initially suggestive of myelolipoma, representing a diagnostic pitfall. Interventions: The patient was managed with intravenous fluids, a continuous nicardipine infusion, and oral alpha-blockade with doxazosin. Empiric broad-spectrum antibiotics were started and later discontinued as infection became unlikely. Beta-blockade was withheld until adequate alpha-blockade was achieved. Supportive care and electrolyte correction were provided. Outcomes: Blood pressure and lactate improved over 48 hours with clinical stabilization. The patient was discharged on oral alpha-blockade with plans for outpatient functional imaging ( 64 Cu-DOTATATE positron emission tomography) and definitive surgical evaluation. Lessons: Pheochromocytoma should be considered in patients presenting with unexplained lactic acidosis and hypertensive crisis, even when sepsis appears likely. Catecholamine-driven type B lactic acidosis can closely mimic infectious shock. Fat-containing adrenal lesions do not exclude pheochromocytoma, and biopsy should be avoided. The temporal association with GLP-1 receptor agonist exposure is hypothesis-generating and warrants further investigation as use of these agents continues to expand.