Evaluation of the Level of Salivary and Serum Cortisol

In spite of its convenience and inexpensiveness, measurement of salivary cortisol has not gained widespread popularity. Indeed, even though its usefulness in the assessment of activity of hypothalamic-pituitary-adrenal (HPA) axis has been reported in various clinical conditions, several centers are still resistant to adopting this procedure. The aim of this study is to evaluate the correlation between salivary and serum cortisol by radioimmunoassay (RIA). This descriptive crass-sectional study carried out in September to February 2005 on 80 patients at laboratory of Ghaem Hospital of Mashhad University of Medical Sciences. A total of 42 women and 38 men aged 46 16.5 were studied. Paired saliva and serum samples were obtained after specialized protocols. Salivary and blood samples were collected at 8 to 9 A.M. Cortisol in saliva and total cortisol in serum were measured with a commercial radioimmunoassay (RIA). Mean serum cortisol was 19.72 8.35 and mean salivary cortisol was 0.18 0.07 µg/dL. Significant linear correlation was found between salivary and serum total cortisol (r=0/35, p<0.001). Results indicate that salivary cortisol measures with radioimmunoassay (RIA) can be used in place of serum total cortisol, based on the evidence that salivary level represents the biologicaly active and free fraction of this hormone, and is non invasive and unstressful.