 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. 