The authors sought to determine whether the performance of the
dexamethasone suppression test (DST) could be enhanced by expressing
cortisol as a function of dexamethasone. Because cortisol concentration is
a function of the reciprocal of dexamethasone concentration, this
relationship was approximated by calculating the product of cortisol and
dexamethasone as a dexamethasone suppression index. Preliminary assessment
of test performance measures (sensitivity, specificity, and predictive
power) showed that use of the dexamethasone suppression index was an
improvement over the use of cortisol levels alone. Factoring dexamethasone
levels into post-dexamethasone cortisol level measures may enhance the
utility of neuroendocrine assessment in psychiatry.Abstract Teaser