An individual on long-term exogenous glucocorticoid administration?

NEET PG Pathology
#1

Which box in the schematic below represents the most likely serum findings for an individual on long-term exogenous glucocorticoid administration?

image

  1. Box A
  2. Box B
  3. Box C
  4. Box D
  5. Box E

View Explanation

Increased serum cortisol, which produces clinical symptoms of Cushing’s syndrome, may be secondary to excess ACTH production or independent of ACTH production. Causes of increased cortisol levels that are independent of ACTH (box E in the diagram) may involve abnormalities of the adrenal gland itself, such as a cortical adenoma or cortical carcinoma, or they may involve exogenous (iatrogenic) corticosteroids. Increased cortisol levels that are dependent on ACTH are associated with excess ACTH production (box B in the diagram) and may result from an abnormality of the pituitary itself, such as a tumor of the anterior pituitary (Cushing’s disease), or from the ectopic production of ACTH outside of the pituitary, such as paraneoplastic syndromes, one example being small cell carcinoma of the lung.

The high-dose dexamethasone suppression test is used to distinguish ACTH-induced Cushing’s disease from the ACTH-independent type. Dexamethasone suppresses pituitary ACTH production, but has no effect on the adrenal gland. Therefore decreased cortisol levels with dexamethasone administration indicate the anterior pituitary as the cause of the ACTHinduced cortisol overproduction.