What is the relation of 'steroid suppression test' with parathyroid gland?

Answer 1

My impression is that the steroid suppression test (Dexamethasone test) is to help differentiate between primary hyperparathyroidism from hypercalcaemia secondary to increased corticosteroids levels. Idea 1: corticosteroids reduce calcium and phosphate absorption and inhibits bone formation (this is the catabolic arm of the cortisol stress response). Therefore, if there is a high level of corticosteroids, the result would be decreased serum calcium and phosphate. Idea 2: Lowered serum calcium and phosphate levels would in turn upregulate parathyroid hormone production to increase serum calcium and phosphate levels caused by Idea 1. Idea 3: A patient with hypercalcaemia could be given a steroid suppression test. If the hypercalcaemia were secondary to the steroids, then one would expect a responsive lowering of parathyroid hormones.