To begin the diagnostic process, your doctor will take a medical history and conduct a physical exam. Then he or she may recommend the following steps:
- GH and IGF-I measurement. After you've fasted overnight, your doctor will take a blood sample to measure your levels of GH and IGF-I. Elevated levels of these hormones suggest acromegaly.
- Growth hormone suppression test. This is the definitive method for verifying acromegaly. In this test, your blood levels of GH are measured before and after you drink a preparation of sugar (glucose). Normally, glucose ingestion depresses levels of GH. If you have acromegaly, your GH level will tend to stay high.
- Imaging. Your doctor may recommend that you undergo an imaging procedure, such as magnetic resonance imaging (MRI), to help pinpoint the location and size of a tumor of your pituitary gland. If radiologists, who usually perform the procedures, see no tumor of your pituitary gland, they may look for nonpituitary tumors that might be responsible for high levels of GH.