<qa>  How many blood samples are collected for the TRH test?The TRH test procedure will be the same for healthy volunteers and patients. All participants fast from midnight before the morning of the test. In the morning, a catheter flexible plastic tube is inserted into an arm vein for easy injection of the TRH and collection of blood samples. Blood pressure is monitored before and during the test. A blood sample is drawn, and then TRH is given through the catheter over a 1-minute period. Another nine blood samples are collected over a 3-hour period from the time of the TRH injection for measuring levels of various hormones. A total of less than 4 tablespoons of blood is taken for the test. 