Can the gold standard be beaten? How reliable are various modifications of the Synacthen test compared to the insulin tolerance test.

摘要

Criteria for the evaluation of the insulin tolerance test (ITT) andSynacthen test are still a matter of debate. The objective of thestudy was to make a comparison of serum and salivary cortisolduring four stimulation tests. Sixty four healthy volunteersunderwent the ITT, the Synacthen test with 1 (LDST), 10 (MDST)and 250 (HDST) μg dose of ACTH. Maximum serum cortisolresponse was observed at the 90 min of the ITT (49 %), HDST(89 %) and MDST (56 %) and at the 40 min of the LDST (44 %).Results expressed as 95 % confidence intervals: 408.0-843.6and 289.5-868.1 nmol/l in the IIT at 60 and 90 min. In the HDSTand the MDST serum cortisol reached the maximum at 90 min542.6-1245.5 and 444.2-871.3 nmol/l. Levels of salivary cortisolfollowed the same pattern as serum cortisol. Salivary cortisolreached the maximum response in the HDST and the MDST at90 min and at 40 min in the LDST. We confirmed good reliabilityof all tests with respect to timing of response and maximumresponse compared to the ITT. We proved that the MDST testcan provide the similar response in serum cortisol to the HDST.Measuring either salivary cortisol or ACTH levels did not provideany additional benefit then measuring serum cortisol by itself.