A 36-year-old female presents to her family physician stating that she has episodes where her heart races, and at these times, she sweats and has a bad headache. She is raising two children on her own, and the episodes often coincide with stressful periods. She is concerned she is having anxiety attacks. Her vital signs are a temperature of 98.7°F, pulse of 82 bpm, and blood pressure of 107/71 mm Hg. Which of the following tests would be most useful for establishing her diagnosis?
a. Measurement of plasma free metanephrines
b. Measurement of plasma catecholamines
c. Serial blood pressures
d. Blood culture
e. CT scan of the head