Diagnosing Acromegaly: An Introduction
In order to make an
acromegaly diagnosis, the doctor will ask a number of questions about a person's medical history, including current symptoms, whether there is a family history of any medical problems, and any medicines the patient is taking. The doctor will also perform a physical exam, looking for any signs of acromegaly, and will order certain tests.
Tests used to help diagnose acromegaly and determine the
acromegaly causes can include:
- Blood tests to measure growth hormone (GH) and/or insulin-like growth factor 1 (IGF-1) levels
- Glucose tolerance test
- Magnetic resonance imaging (MRI scan)
- Computed tomography (CT scan).
GH Levels and Diagnosing Acromegaly
If a doctor suspects a patient has acromegaly, he or she can measure the GH level in the blood after a patient has fasted overnight to determine if it is elevated. However, a single measurement of an elevated blood GH level is not enough to make an acromegaly diagnosis. GH is secreted by the pituitary in spurts, and its concentration in the blood can vary widely from minute to minute. At any given time, a patient with acromegaly may have a normal GH level, whereas a GH level in a healthy person may be five times higher.
Glucose Tolerance Test Used in Diagnosing Acromegaly
Because of these problems, more-accurate information can be obtained when GH is measured under conditions in which GH secretion is normally suppressed. Physicians often use the oral glucose tolerance test to diagnose acromegaly, because ingestion of 75 grams of the sugar glucose lowers blood GH levels less than 2 ng/mL (nanograms per milliliter) in healthy people. In patients with GH overproduction, this reduction does not occur. The glucose tolerance test is the most reliable method of confirming an acromegaly diagnosis.
