Intraindividual stability of cortisol and cortisone and the ratio of cortisol to cortisone in saliva, urine and hair.

Background Cortisol, cortisone and the ratio of cortisol to cortisone in saliva, urine and hair are acute, short-term and long-term biomarkers to reliably assess the activity of hypothalamic-pituitary-adrenal (HPA) axis and 11 β -hydroxysteroid dehydrogenase (11 β -HSD). One key issue is whether these biomarkers have intraindividual relative stability. Salivary, urinary and hair cortisol was proven to show considerable long-term intraindividual relative stability. However, currently unknown is whether cortisone and the ratio in saliva, urine and hair show intraindividual relative stability. Methods The present study utilized a longitudinal design to validate long-term stability within two weeks of three biomarkers in saliva and urine, and long-term stability within twelve months of three hair biomarkers. Salivary, urinary and hair steroids were measured with high performance liquid chromatography tandem mass spectrometry. Results Three biomarkers in urine and hair showed moderate test-retest correlations with coefficient ( r ) ranging between 0.22 and 0.56 and good multiple-test consistencies with coefficient of intraclass correlation ( ICC ) ranging between 0.42 and 0.67. Three single-point salivary biomarkers showed weak to moderate test-retest correlations ( r’s between 0.01 and 0.38) and poor to fair multiple-test consistencies ( ICC’s between 0.29 and 0.53) within two weeks. Three single-day salivary biomarkers showed moderate test-retest correlations ( r’s between 0.23 and 0.53) and good multiple-test consistencies ( ICC’s between 0.56 and 0.66) within two weeks. Conclusions Three biomarkers in urine and hair showed moderate long-term intraindividual relative stability. Three single-point salivary biomarkers showed weak to moderate short-term and long-term intraindividual relative stability, but three single-day salivary biomarkers showed moderate short-term and long-term intraindividual relative stability. [ABSTRACT FROM AUTHOR]