Relationship between Cortisol Increment and Basal Cortisol: Implications for the Low-Dose Short Adreno- corticotropic Hormone Stimulation Test, Suhail A.R.

Background: We analyzed the low-dose (1 g) rapid adrenocorticotropic hormone test (LDST) in 17 patients with a normal hypothalamic-pituitary-adrenal axis to determine reference intervals for the LDST on the basis of poststimulation cortisol increments. Methods: We analyzed test results for 17 patients (14 females and 3 males; age range, 18–46 years) who had received a 2-mL aliquot of low-dose (1 g) adrenocorti-cotropic hormone prepared from one 250-g vial of Synacthen diluted in 500 mL of sterile normal saline solution. Sampling took place at 0, 20, 30, and 60 min post stimulation. The cortisol increment was plotted against basal cortisol. Results: We observed a marked interdependence of the basal cortisol concentration with the increase in cortiso