Late-night saliva cortisol test

What this test is

Cortisol is a stress hormone. Normally it drops very low late at night. In Cushing's syndrome, a rare illness with too much cortisol, it stays high. A saliva sample taken at bedtime can check for this. It is a proven test, but only when other signs point to Cushing's, such as easy bruising, a red round face, new wide purple stretch marks, or weak thigh and shoulder muscles. Without those signs, a high result is more likely to be a false alarm than real disease. If the test is abnormal, your doctor will repeat it or use a second test, and may send you to a hormone specialist.