A 41-year-old woman comes to the physician for a 4-month history of increasing fatigue. She is an avid traveler and visited Honduras 6 months ago. Serum laboratory studies show:
Sodium 137 mEq/L
Potassium 5.6 mEq/L
Bicarbonate 22 mEq/L
Leukocytes 8,000/μL
Eosinophils 26%
Which of the following is the next best step in diagnosis?
A) ACTH stimulation test
B) Dexamethasone suppression test
C) Measure serum iron and ferritin
D) Stool nematode toxin test
E) Stool smear for ova and parasites
