BACKGROUND
Severe obstructive sleep apnea and acute physiological stress can complicate interpretation of metanephrine testing for pheochromocytoma and paraganglioma (PPGL).
CASE REPORT
A 23-year-old woman with class III obesity, previously diagnosed hypertension, and a maternal history of postpartum cardiomyopathy presented with edema, exertional dyspnea, palpitations, and severe hypertension. Echocardiography showed an ejection fraction of 30%, and chest computed tomography angiography identified subsegmental pulmonary emboli. Urinary metanephrines were reported as elevated during the acute illness, prompting evaluation for PPGL. Abdominal magnetic resonance imaging and reportedly normal repeat outpatient metanephrine testing reduced suspicion for PPGL, although quantitative repeat results and testing conditions were unavailable. Subsequent polysomnography demonstrated severe obstructive sleep apnea, with an apnea-hypopnea index of 46.8 events/hour and an oxygen saturation nadir of 77%. Continuous positive airway pressure (CPAP) was initiated alongside guideline-directed heart-failure treatment. Obstructive sleep apnea was considered a possible contributor within a multifactorial presentation; other endocrine causes of secondary hypertension were not documented as excluded. An ejection fraction of 40% was reported during cardiac evaluation, but its timing relative to CPAP initiation could not be established.
CONCLUSIONS
Severe obstructive sleep apnea should be considered in patients with obesity, hypertension, and witnessed apneas when metanephrine testing raises concern for PPGL. The biochemical findings require interpretation in the context of acute illness and appropriate reassessment after clinical stabilization. This case does not establish obstructive sleep apnea as the cause of the cardiac dysfunction or pulmonary emboli.

Keywords: Heart Failure, Systolic; Pulmonary Embolism; Sleep Apnea, Obstructive; Pheochromocytoma