[Skip to Content]
[Skip to Content Landing]
Article
May 1985

Plasma Cortisol Determination for the Dexamethasone Suppression TestComparison of Competitive Protein-Binding and Commercial Radioimmunoassay Methods

Author Affiliations

From the Department of Psychiatry, Duke University, Durham, NC (Mr Ritchie and Dr Carroll); and the University of Michigan, Mental Health Research Institute, Ann Arbor (Mss Olton and Shively and Dr Feinberg).

Arch Gen Psychiatry. 1985;42(5):493-497. doi:10.1001/archpsyc.1985.01790280075007
Abstract

• Quality control serum samples and postdexamethasone plasma pools were used to compare 16 commercial cortisol radioimmunoassay kits with the competitive protein-binding assay for plasma glucocorticoids that we used to standardize the dexamethasone suppression test (DST). Thirteen radioimmunoassays gave higher criterion values for the DST than those established using the competitive protein-binding assay. The range of radioimmunoassay criterion values was 4.34 to 8.70 μ Possible explanations are given for these findings, and their importance to the clinical utility of the DST are emphasized. Each laboratory should validate its own criterion cortisol value for depression based on local data, including appropriate control groups.

×