Cushing’s Syndrome: The Daily PANCE Blueprint

The answer is A. Measure 24-hour urinary free cortisol

This patient’s presentation is consistent with Cushing syndrome, which is characterized by weight gain (particularly central obesity), easy bruising, muscle weakness, and hypertension. The rounded face (“moon face”) and the fat pad between the shoulders (“buffalo hump”) are also classic features of Cushing syndrome. The next step in evaluation is to confirm the presence of hypercortisolism by measuring 24-hour urinary free cortisol. This is a highly sensitive and specific initial screening test for Cushing syndrome, which measures the total amount of cortisol excreted in the urine over a 24-hour period. Other screening tests for hypercortisolism include late-night salivary cortisol and the 1 mg overnight dexamethasone suppression test.

Incorrect Answer Explanations:

• B. Order a brain MRI with focus on the pituitary gland
  A brain MRI to evaluate the pituitary gland is indicated only after confirming hypercortisolism. If Cushing syndrome is confirmed, the next step is to determine the source of excess cortisol production. This typically involves further biochemical testing, followed by imaging. MRI of the pituitary is used to identify an ACTH-secreting pituitary adenoma (Cushing disease), but it should not be done as the initial step.
• C. Perform a thyroid uptake and scan
  A thyroid uptake and scan would be indicated in the evaluation of hyperthyroidism, but this patient does not present with symptoms consistent with thyroid hormone excess. Her TSH is within the normal range, and her symptoms (weight gain, bruising, muscle weakness) are more indicative of Cushing syndrome rather than thyroid disease.
• D. Initiate treatment with metformin
  While this patient has elevated fasting glucose levels, which suggests insulin resistance or diabetes, initiating treatment with metformin is not the most appropriate next step. The underlying cause of her symptoms needs to be evaluated first. The hyperglycemia seen here is likely secondary to Cushing syndrome, and treating the underlying condition is key to addressing her metabolic abnormalities.
• E. Refer for a sleep study to evaluate for sleep apnea
  Obesity and fatigue can be associated with obstructive sleep apnea (OSA); however, this patient’s constellation of symptoms—easy bruising, muscle weakness, central obesity, and a buffalo hump—is more consistent with Cushing syndrome rather than OSA alone. A sleep study would not address the primary pathology here, and further evaluation of hypercortisolism should be prioritized.