Measurement of Cortisol in Saliva Using a Commercial Radioimmunoassay Developed for Serum. Messung von Speichel-Cortisol mittels eines kommerziellen Serum-Radioimmunoassays

Abstract

A commercially available radioimmunoassay developed for the determination of coriisol in human plasma and serum was used to measure salivary cortisol. Clearly elevated levels for spiked saliva (3-10 fold: P/B regression: y = 1.9x + 6.4; r = 0.983) were found. We suggest that differing biochemical conditions in the standard material (plasma) and the sample matrix (saliva) were responsible for the elevated measurements. For this reason we adapted the assay by replacing the original plasma standards by in-house saliva standards. In addition the concentrations of the antibodies and the tracer were decreased and the time for incubation was increased. After adaptation, cortisol could be measured in excellent accordance with the amounts added to the saliva samples (P/B regression: y = 1.03x -0.01; r = 0.998). The 50% intercept was 8 ng/ml. We measured intra-assay variation coefficients of 7.9% (1 ng/ml) and 6.1% (10 ng/ml), respectively. Inter-assay variation coefficients were 11.2% (1 ng/ml) and 9.6% (10 ng/ml), respectively. Saliva samples of healthy volunteers measured after adaptation were in good accordance with data from in-house assays reported in the literature. There was no disturbing influence of either dental care or food intake on the reproducibility of salivary cortisol levels by this specific assay (p=0.76 and p>0.05, respectively). After adaptation, the assay is therefore a reliable tool for salivary cortisol measurement. · Zusammenfassung: Ein kommerziell erhältlicher Radioimmunoassay zur Messung von Cortisol in humanem Plasma und Serum wurde auf seine Verwendbarkeit zur Messung von Cortisol im Speichel über-prüft. Es ergaben sich 3-10fach erhöhte Werte in Speichelproben, welche mit exogenem Cortisol versetzt wurden (P/B Regression: y = l,9x + 6,4; r = 0,983). Wir nehmen an, daß die unterschiedliche biochemische Zusammensetzung des Standardmaterials (Plasma) und der Probenmatrix (Speichel) der Grund.für die falsch-hohen Messungen ist. Der Assay wurde fol-

Testing the Effect of Medical Positive Reinforcement Training on Salivary Cortisol Levels in Bonobos and Orangutans

“…All training sessions were carried out between 19 th February and 24 th April 2008 and started at 14:00±10 min. This time window for medical PRT was chosen for two reasons: First, to avoid interference with feeding times and therefore with food, which may affect measurements of enzymes and hormones in saliva [62] but see also [63] . Second, midday was chosen for sample collection to minimize confounding effects of diurnal variation of salivary cortisol [58] , [64] .…”

Validation of a Commercial Enzyme-Linked Immunosorbent Assay for Allopregnanolone in the Saliva of Healthy Pregnant Women

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