engleski

Enzyme-linked immunosorbent assay for determining cortisol in saliva

Cortisol is one of the main hormonal regulators of the stress response. In saliva cortisol is traditionally analysed by radioimmunoassays (RIA). The use of radioisotopes, hazardous solvents and expensive scintillation counters is sometimes not desirable, thus there was a need to develop equally sensitive, yet low-cost, high throughput and safe method. Here we describe an enzyme-linked immunosorbent assay (ELISA) for indirect assay of cortisol in saliva. In the assay, an immobilized anti-cortisol antibody is used to capture cortisol in the sample. Using competition with biotin-labeled cortisol (tracer) and streptavidin/alkaline-phosphatase detection system we were able to acurately measure cortisol at levels normally found in saliva (1- 30 nmol/l) with acceptable inter- and intra-assay coefficients of variation (6,96% and 2,67%). Using this method we have analysed circadian variations of cortisol in diagnosed PTSD patients, active professional soldiers and control individuals. Interestingly, though PTSD is considered to be a single disorder, we found that PTSD patients separate into two well characterised groups, one with significantly smaller and one with significantly increased circadian variations of cortisol.

stress; cortisol; saliva

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