The short Synacthen test in acute hospital admissions

Summary. objective We wished to define the cortisol response to 250 μg intramuscular tetracosactrin (Synacthen) in acute hospital admissions, using a modern Immunoassay for cortisol. design We performed a prospective study of, as near as possible, a consecutive series of 161 admissions to a single unit. patients We studied 50 patients (age range 67–98, mean 80.3 years, 31‐female, 19‐male) admitted as an emergency, from whom it was possible to obtain informed consent, and whom it was possible to study within 24 hours of admission.measurements We measured baseline, increment and peak serum cortisol following administration of 250 μg intramuscular tetracosactrin between 0800 and 0900 hours. results Baseline cortisol concentrations ranged from 288 to 1585 nmol/I (mean 706; median 665). Peak cortisol concentrations ranged from 602 to 2265 nmol/I (mean 1076; median 999). Baseline and peak cortisol concentrations showed a significant correlation ( P < 0.001). Increment varied from 10 to 747 nmol/I (mean 374; median 336) and did not correlate with baseline. conclusions In acute hospital admissions, baseline serum cortisol between 0800 and 0900 hours should exceed 250 nmol/I. Peak serum cortisol after 250 μg intramuscular tetracosactrin should exceed 600 nmol/I. Calculation of the increment is of no value.