If Cushing’s syndrome is suspected in the evaluation of osteoporosis, which additional test should be considered?

• A. Fasting glucose test.
• B. BMI measurement.
• C. Cortisol level testing.
• D. TSH test.

Answer: (C)

When osteoporosis prompts consideration of a secondary cause, showing hypercortisolism is essential because excess cortisol directly undermines bone health. Cortisol overactivity both decreases bone formation and increases bone resorption, while also reducing calcium absorption from the gut and increasing urinary calcium loss. Testing cortisol levels helps confirm or rule out Cushing’s syndrome as the contributing factor, with common screening options including 24-hour urinary free cortisol, overnight dexamethasone suppression test, or late-night salivary cortisol. The other tests listed don’t specifically diagnose Cushing’s: fasting glucose can be altered by many factors, BMI is just a weight measure, and TSH evaluates thyroid function rather than cortisol excess.