Measuring cortisol levels in saliva at night has excellent specificity and sensitivity for screening Cushing's syndrome. Water in saliva accounts for more than 99%, 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 affecting salivary secretion, such as internal and external factors. Therefore, the saliva composition is not constant enough, and the collection time should be limited to 2-4h in the afternoon.
Decrease: seen in adrenal cortical tuberculosis and atrophy, hypophysis, hypothyroidism, chronic consumptive diseases, amyloidosis, leukemia, congenital adrenocortical hyperplasia, CBG (corticosterone binding globulin) deficiency, etc. Rise: in adrenal hyperplasia, tumor (such as adrenal tumor, pancreatic cancer, thyroid cancer, testicular cancer, breast cancer), simple obesity, surgery, trauma, myocardial infarction, oat cell lung cancer, hyperthyroidism and so on.
When collecting saliva, rinse with warm water and collect it 5-10min after rinsing. When collecting, you can directly use a catheter to suck from the opening of each gland, or collect the naturally flowing saliva in a clean test tube. If it is not easy for saliva to flow out naturally, you can use a small amount of sterile absorbent cotton to put it under the tongue for a few minutes, and take out the extruded cotton ball to get saliva.