Salivary cortisol

Measuring cortisol levels in saliva at night has excellent specificity and sensitivity for screening Cushing's syndrome. Saliva contains more than 99% of water, of which organic matter accounts for about 0.5% and inorganic matter accounts for about 0.2%. In addition, there are a small number of red blood cells, epithelial cells and so on. There are many factors that affect saliva secretion, such as internal and external factors. Therefore, the saliva composition is not constant enough, and the collection time is preferably limited to 2 to 4 hours in the afternoon.