A 35-year-old man presents with fatigue, loss of libido, and lethargy for the last 3 years. He has no medical history. He takes a multivitamin but no other medications. He smokes 1 pack of cigarettes every week and drinks 1 glass of wine each night. He does not use drugs. He is the manager at a retail clothing store.

His review of symptoms is notable for a 15-pound weight loss since his last visit 3 years ago. Vitals are: temperature 37.4 °C, heart rate 95 beats/minute, blood pressure 110/65 mm Hg, respiratory rate 14 breaths/minute, and oxygen saturation 99% on room air. Findings on his head, ears, eyes, nose, and throat examination as well as examinations of his neck, heart, lung, abdomen, and neurologic status are all normal. His skin appears tanned, even under his clothes.

You order laboratory studies that show a normal complete blood count, sodium level of 130, potassium level of 5.1, chloride level of 110, bicarbonate level of 25, blood urea nitrogen level of 13, creatinine level of 0.8, and glucose level of 90. The early morning serum cortisol level is 2.5 µg/dL. You suspect primary adrenal insufficiency.

Answer Options:

random serum cortisol and adrenocorticotropic hormone (ACTH) levels

24-hour urine cortisol excretion

standard high-dose short adrenocorticotropic hormone (ACTH) stimulation test

antiadrenal antibodies

low-dose corticotrophin stimulation test