Insulin Tolerance Test
Blood samples will be drawn five times at different intervals. A first sample for blood glucose, cortisol, and growth hormone will be taken between 6 am and 8 am.
Then, insulin will be given through the IV. The insulin should make the blood glucose level go down, which should make the GH level go up. Blood samples will be collected at 30, 60, 90, and 120 minutes for glucose, cortisol, and growth hormone.
If the blood sugar has not dropped to a certain level after 45 minutes, a repeat dose of insulin will be given. The blood sample will be collected 75 minutes and 150 minutes later.
If the blood sugar levels fall too low, a high dose of sugar will be given by IV, followed by a sugar infusion.
Growth Hormone-Releasing Hormone, Arginine, Growth Hormone-Releasing Peptide
The blood sample will be drawn five times at different intervals. The first sample will be taken between 6 am and 8 am.
Arginine or GH-releasing peptide will be given through the IV for 30 minutes.
Once the arginine or GH-releasing peptide has been administered, GH-releasing hormone will be given by IV.
This should stimulate the pituitary to release GH. The last four blood samples will be drawn every 30 minutes following both infusions.
Note: GHRH is not currently available commercially in the United States.