A 45-year-old woman presents with a several-month history of…
A 45-year-old woman presents with a several-month history of progressive fatigue, muscle weakness, unintentional weight loss of 15 pounds, and episodes of dizziness upon standing. On examination, you note diffuse hyperpigmentation of her skin, particularly in the palmar creases and buccal mucosa, and a blood pressure of 90/60 mmHg. You suspect primary adrenal insufficiency. Which of the following laboratory panels would be the most appropriate initial investigation to order?