Endocrine tests are usually hormone tests and the best time depends on the specific content of the test. Endocrine tests vary in time depending on the hormone. Sex hormones are usually checked on day 2-3 of the menstrual cycle; cortisol is usually taken at 8:00 am, 4:00 pm and 0:00 pm during the night when cortisol secretion peaks in inpatients, and at 8:00 am in outpatients; prolactin is best checked at 10:00 am; growth hormone is usually measured at 11:00-1:00 pm at night; insulin is measured at 7:00 am: Insulin is measured at 7:00-8:00 a.m. on an empty stomach, then half an hour, one hour, two hours and three hours after a meal; thyroid hormone tests can be performed at any time of the day, etc. Endocrine tests usually require patients to take blood after 10 minutes of rest so that blood taken during activity or emotional stress does not reflect the true basal level.