Acromegaly Tests: Why Blood Tests and Imaging Have Different Jobs

If an endocrinology referral includes several unfamiliar test names, ask the team to write down what each appointment is for. Keep the preparation instructions and the results conversation beside those names, so you know what happens next.

IGF-I helps assess growth-hormone activity

Growth-hormone levels change throughout the day. Clinicians can measure insulin-like growth factor I, or IGF-I, to assess growth-hormone activity. NIDDK says a high IGF-I level usually suggests acromegaly.¹

Ask the clinician how your result fits with the reason for referral and whether another test is needed. Request an explanation of the next step before trying to draw a conclusion from a laboratory flag yourself.

The glucose drink tests the hormone response

NIDDK describes an oral glucose tolerance test in which a person drinks a sugary liquid and has repeated blood samples. The team measures growth hormone: it normally falls after the drink, while insufficient suppression supports the diagnosis of acromegaly.¹

Confirm that your appointment is for this growth-hormone assessment. Ask the clinic for its own instructions about food, drink, medicines, arrival time and how long to allow. Contact it if any instruction is unclear or conflicts with another treatment plan. Do not change prescribed medicine on your own.

Imaging looks for the cause

After blood tests confirm excess growth hormone, imaging can locate and measure a possible tumor. MRI is the preferred pituitary scan; CT may be used when MRI is unsuitable. If no pituitary tumor is found, clinicians investigate other possible tumor locations.¹

Ask which scan has been requested and who will discuss it with you. Give the imaging team the information its screening form requests, and ask for help completing anything you do not understand.

Put the findings into one conversation

Before leaving the results appointment, ask what the team has established, what remains uncertain and which follow-up is needed. Request a written plan with the next appointment and the contact for questions.

If you have several reports, ask the clinician to explain how they fit together. Keep your questions with the full reports rather than keeping only an isolated number in your notes.

My Body Changed. Now What? includes the Visit Brief. Use it to organize questions for the specialist discussion; it does not interpret hormone tests. See the book.