483. - Determination of salivary cortisol by non-radioisotopic immunoassay

Abstract

T measurement of cortisol in saliva has received considerable attention over the past few years. In blood, cortisol is largely bound to plasma proteins, whereas saliva contains no corticosteroid-binding proteins (1). Salivary cortisol has been correlated directly with the biologically active, nonprotein-bound plasma cortisol (1–3). Under stimulation, changes in salivary cortisol may be greater in magnitude than those observed in plasma (4). In addition, the cortisol level in saliva is not affected by physiological variations in the rate of saliva production or by cigarette smoking. Thus, these and other factors have led us to believe that measurement of salivary cortisol is a valid assessment of cortisol responsivity. Such a measurement has been applied to assess neuroendocrine disturbances in patients with affective disorders (2), children at risk for a psychoactive substance use disorder (5), and patients with chronic posttraumatic stress disorder (6). Salivary cortisol concentrations are ,10% of those in plasma, therefore, the method used to assay salivary cortisol requires a sensitive, but tedious radioimmunoassay (4,7). The purpose of our present study is to test whether another nonisotopic immunoassay is suitable for salivary cortisol measurement. The dissociation-enhanced lanthanide fluoroimmunoassay (DELFIAt) is a solid phase timeresolved fluoroimmunoassay, which has been applied extensively to determine serum and urine cortisol levels. The present findings suggest that the DELFIA procedure without cortisol extraction provides a reliable, accurate, and convenient alternative to assay for salivary cortisol.