There are several ways to diagnose acromegaly. The type of assessments and when you have them may be different for each person and depends on your medical history and treating physician.
Growth hormone (GH) level
GH is released from the pituitary gland in spurts, or pulses. The rate of the pulses changes depending on the time of day and is slightly different for each person. Because of the variability in the pulses, measuring GH in the blood is not useful on its own to make a diagnosis. Instead, the GH level in the blood is used with other assessments to confirm a diagnosis.
IGF-1 (insulin-like growth factor-1) level
IGF-1 hormone is released from the liver in response to GH release, or secretion, from the pituitary gland. IGF-1 is not released in the same spurt, or pulse, pattern as GH, thus high levels of IGF-1 are a better indicator of too much GH in the blood. Remember, GHRH (growth-hormone-releasing hormone) from the hypothalamus causes GH release from the pituitary gland, which causes IGF-1 production and release from the liver.
GH response to oral glucose tolerance testing
GH has many effects on the body, one of which is sugar, or glucose, metabolism. Too much GH in the blood can cause your blood sugar to rise.
Your doctor can assess how well your body tolerates sugar by giving you a very sugary drink and then measuring your GH levels at different time points after you finish the drink. This process is called an oral glucose tolerance test. If you have acromegaly, your GH levels will remain high after this test.
Prolactin hormone level
Some pituitary adenomas produce and release the hormone prolactin in addition to GH. If the adenoma is releasing prolactin, you may have symptoms of milk discharge from the breasts, infertility, low sex drive, and impotence.
MRI (magnetic resonance imaging)
MRI scans allow doctors to take pictures of organs and tissues inside the body. An MRI scan of the pituitary gland will help your doctor determine if there is a pituitary adenoma causing acromegaly.
Other assessments for acromegaly
Your doctor may order other assessments to aid in the diagnosis of acromegaly including assessing the levels of other pituitary hormones to see if they are lower because of the adenoma.
After your diagnosis, your doctor may order more assessments to see how acromegaly is affecting your body and determine your course of treatment.
Other assessments your doctor may order after your diagnosis include:
- Colonoscopy to see if polyps are growing inside your colon
- Echocardiogram and electrocardiogram to see how acromegaly is affecting your heart
- Sleep assessment to see if your sleep is being affected (if you have sleep apnea)
- Fasting glucose and HbA1c blood work to assess your blood sugar levels
Check out the true-2-me guest editorial on treatment Considerations for Acromegaly