Another simple technique to calculate time difference in Excel is using the TEXT function: 1  Calculate hours between two times: =TEXT(B2-A2, h) 2  Return hours and minutes between 2 times: =TEXT(B2-A2, h:mm) 3  Return hours, minutes and seconds between 2 times: =TEXT(B2-A2, h:mm:ss)
Because cortisol levels change throughout the day, the timing of a cortisol test is important. A cortisol blood test is usually done twice a dayâonce in the morning when cortisol levels are at their highest, and again around 4 p.m., when levels are much lower. Cortisol may also be measured in a urine or saliva test. For a cortisol urine test, your health care provider may ask you to collect all urine during a 24-hour period. This is called a 24-hour urine sample test. It is used because cortisol levels vary throughout the day.
Overnight suppression test: Serum cortisol is checked at baseline, then dexamethasone (typically 8 mg) is given orally between 11 pm and midnight. Cortisol level is then checked between 8 am and 9 am the next morning.he 24-hour urine free cortisol test may be used during the second day of the standard test as an end point; however, data suggest that serum cortisol has higher diagnostic accuracy and conducting both tests is not recommended.