TY - JOUR
T1 - Plasma dexamethasone concentrations and the dexamethasone suppression test
AU - Ritchie, James C.
AU - Belkin, Beth M.
AU - Ranga, K.
AU - Krishnan, R.
AU - Nemeroff, Charles B.
AU - Caroll, Bernard J.
N1 - Funding Information:
From the Departments of Psychiatry (J.C.R., B.M.B., K.R.R.K., C.B.N., B.J.C.) and Pharmacology (C.B.N.), versity, Durham, NC. Supported in part by NIMH Grants MH 39593, MH 40159, and MH 42510. Address reprint requests to Dr. J. C. Ritchie, Department of Psychiatry, Duke University, Durham, NC 27710. Received February 16, 1988; revised January 23, 1989.
Copyright:
Copyright 2014 Elsevier B.V., All rights reserved.
PY - 1990/1/15
Y1 - 1990/1/15
N2 - Altered bioavailability or altered pharmacokinetics of dexamethasone (dex) may contribute to a positive Dexamethasone Suppression Test (DST) in psychiatric patients. We measured plasma dex and plasma cortisol concentrations in 32 patients with primary major depressive disorder (MDD), 14 patients with other psychiatric disorder, and 16 normal controls. Cortisol was measured by the competitive protein binding (CPB) assay and dex by RIA (IgG Corp.). Additionally, cortisol was measured by a fluorescent polarization immunoassay (FPIA) available on the Abbott TDx analyzer in an attempt to validate this method for the use in the DST. The agreement between FPIA and CPB cortisol results was excellent. Depressed nonsuppressors, by definition, had significantly higher mean plasma cortisol concentrations than depressed suppressors, psychiatric controls and normal volunteers at 8:00 AM, 3:00 PM, and 10:00 PM postdex. When DST nonsuppressors and suppressors were compared regardless of diagnostic group, plasma dex concentrations were significantly lower (p < 0.01) in the DST nonsuppressors. There was a significant negative correlation between plasma cortisol levels and plasma dex levels across all subjects at 8:00 AM (r = -0.365, n = 44, p < 0.05). When the subjects were sorted by diagnostic category, there was a strong, but not statistically significant, trend toward lower plasma dex concentrations in the melancholic nonsuppressors versus the melancholic suppressors and between the psychiatric control non-suppressors and the corresponding suppressors group. These relationships disappeared when we restricted our analyses to an empirically derived middle range of plasma dex concentrations within which the DST results were considered to be valid. We conclude that bioavailability or pharmacokinetics of dex may significantly contribute to DST results. Further investigation is needed to determine whether or not the quantification of dex and its metabolites and their determination at which specific timepoints during the DST will enhance the predictive or interpretive value of the DST in psychiatric patients.
AB - Altered bioavailability or altered pharmacokinetics of dexamethasone (dex) may contribute to a positive Dexamethasone Suppression Test (DST) in psychiatric patients. We measured plasma dex and plasma cortisol concentrations in 32 patients with primary major depressive disorder (MDD), 14 patients with other psychiatric disorder, and 16 normal controls. Cortisol was measured by the competitive protein binding (CPB) assay and dex by RIA (IgG Corp.). Additionally, cortisol was measured by a fluorescent polarization immunoassay (FPIA) available on the Abbott TDx analyzer in an attempt to validate this method for the use in the DST. The agreement between FPIA and CPB cortisol results was excellent. Depressed nonsuppressors, by definition, had significantly higher mean plasma cortisol concentrations than depressed suppressors, psychiatric controls and normal volunteers at 8:00 AM, 3:00 PM, and 10:00 PM postdex. When DST nonsuppressors and suppressors were compared regardless of diagnostic group, plasma dex concentrations were significantly lower (p < 0.01) in the DST nonsuppressors. There was a significant negative correlation between plasma cortisol levels and plasma dex levels across all subjects at 8:00 AM (r = -0.365, n = 44, p < 0.05). When the subjects were sorted by diagnostic category, there was a strong, but not statistically significant, trend toward lower plasma dex concentrations in the melancholic nonsuppressors versus the melancholic suppressors and between the psychiatric control non-suppressors and the corresponding suppressors group. These relationships disappeared when we restricted our analyses to an empirically derived middle range of plasma dex concentrations within which the DST results were considered to be valid. We conclude that bioavailability or pharmacokinetics of dex may significantly contribute to DST results. Further investigation is needed to determine whether or not the quantification of dex and its metabolites and their determination at which specific timepoints during the DST will enhance the predictive or interpretive value of the DST in psychiatric patients.
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U2 - 10.1016/0006-3223(90)90646-J
DO - 10.1016/0006-3223(90)90646-J
M3 - Article
C2 - 2294980
AN - SCOPUS:0025166631
VL - 27
SP - 159
EP - 173
JO - Biological Psychiatry
JF - Biological Psychiatry
SN - 0006-3223
IS - 2
ER -