title: Comparison of tests of stress-released cortisol secretion in pituitary disease.
abstract: OBJECTIVE
  We wished to compare peak and incremental rise in plasma cortisol in response to insulin induced hypoglycaemia (IIH) stress test, i.m. glucagon stimulation test (IMGST) and short Synacthen test (SST) in patients with pituitary disease, using a modern radioimmunoassay for cortisol. We compared the three stimulants using receiver operator characteristic (ROC) plots, assuming a cortisol threshold of 500 nmol/l or 580 nmol/l for the IIH stress test which we used as the standard from which to evaluate the SST and the IMGST.
  
  
  METHODS
  We prospectively studied 16 patients (8F, 8M mean age 43.69 +/- 3.72 years) admitted to the investigation ward for IIH stress test and who were asked to undergo two additional tests (IMGST and SST) on consecutive days.
  
  
  METHODS
  We measured serum cortisol at baseline, 30, 45, 60, 90 and 120 minutes during the IIH stress test; baseline, 150 and 180 minutes during GST, and baseline and 30 minutes during the SST.
  
  
  RESULTS
  There was a significant rise in cortisol from baseline in all tests (P < 0.001). There was no significant difference among the peak plasma cortisol responses or the incremental rises in plasma cortisol following IMGST, SST and IIH stress test (repeated measures ANOVA F = 0.704, P = 0.503; F = 0.238, P = 0.79). The ROC plots clearly showed that the SST has poor diagnostic utility at both IIH thresholds, compared with the IMGST.
  
  
  CONCLUSIONS
  The peaks and incremental rises in cortisol following all three tests are comparable. Using the insulin induced hypoglycaemia stress test as a reference and peak cortisol thresholds of 500 and 580 nmol/l as discriminating variables, the short Synacthen displayed poor diagnostic utility when compared to the i.m. glucagon stimulation test. The short Synacthen may be misleading if used as a screening test as advocated by a number of authors.
authors.affiliation: Department of Endocrinology, General Infirmary at Leeds, UK.
authors.forename: S M
authors.initials: SM
authors.lastname: Orme
authors.forename: S R
authors.initials: SR
authors.lastname: Peacey
authors.forename: J H
authors.initials: JH
authors.lastname: Barth
authors.forename: P E
authors.initials: PE
authors.lastname: Belchetz
mesh_terms: D000328:Adult; D000704:Analysis of Variance; D003366:Cosyntropin; D005260:Female; D005934:Glucagon; D006801:Humans; D006854:Hydrocortisone / Q000097:blood / Q000378:metabolism*; D007273:Injections, Intramuscular; D007328:Insulin; D008297:Male; D008875:Middle Aged; D010900:Pituitary Diseases / Q000097:blood / Q000175:diagnosis* / Q000503:physiopathology; D010901:Pituitary Function Tests; D010902:Pituitary Gland / Q000503:physiopathology*; D011237:Predictive Value of Tests; D011446:Prospective Studies; D011863:Radioimmunoassay
chemical_list: D007328:Insulin; D003366:Cosyntropin; D005934:Glucagon; D006854:Hydrocortisone