Plasma dexamethasone levels in children given the dexamethasone suppression test

Abstract

To determine whether children who demonstrate dexamethasone suppression test (DST) nonsuppression have lower plasma dexamethasone levels than DST suppressors, we administered the DST to 73 patients ranging in age from 5–14 years. Plasma dexamethasone levels and postdexamethasone cortisol levels were measured at 4:00 pm on day 2. We found: (1) DST nonsuppressors had significantly lower plasma dexamethasone levels ( p < 0.03) than suppressors; similar trends were observed when the population was divided into depressed and nondepressed patients; (2) mg/m 2 dose of dexamethasone was directly correlated with plasma dexamethasone ( p < 0.003) and inversely correlated with postdexamethasone plasma cortisol levels ( p < 0.04); and (3) a statistically significant inverse correlation between plasma dexamethasone levels and postdexamethasone cortisol levels ( p < 0.04). Our findings show that plasma dexamethasone levels are important in evaluating DST results in psychiatrically disturbed children and suggest that dexamethasone dosage for use in the DST in children might be better calculated in terms of body surface area.