Question

A 42-year-old woman presents to the clinic with a 6-month history of progressive weight gain, generalized weakness, and easy bruising. Her medical history includes new-onset type 2 diabetes mellitus and treatment-resistant hypertension. Blood pressure is 168/102 mm Hg. Physical examination reveals a plethoric face, dorsocervical fat pad, prominent violaceous abdominal striae, and significant proximal muscle weakness. She denies the use of over-the-counter supplements, intra-articular injections, or prescribed medications other than her antihypertensives. Laboratory testing shows a serum potassium of 3.1 mEq/L and a fasting blood glucose of 145 mg/dL. Endogenous hypercortisolism is suspected, and surgical management may be required if a central etiology is confirmed.

Arrange the following diagnostic laboratory evaluations in the most appropriate sequential order to definitively establish the diagnosis and source of this patient's condition, from the initial step to the final invasive evaluation.