Cortisol Assay, 2 Samples: PRE (Baseline) and POST Dexamethasone Suppression
Specimen
PRE: 0.5 mL serum in red top, white top, or serum separator tube for baseline sample (labeled PRE); each POST: 0.5 mL serum in red top, white top, or serum separator tube for each post sample (labeled POST)
Test Description
This test measures cortisol concentrations before and after administration of exogenous dexamethasone (0 hours followed by an 8 hour sample). This is only a two cortisol assay. The low dose dexamethasone suppression test, a three cortisol sample test (CDEX3), is preferred for diagnosing hyperadrenocorticism. The high-dose dexamethasone suppression test, a three cortisol sample test, is used to differentiate pituitary-dependent from adrenal tumor hyperadrenocorticism.