What Is a Glucagon Test?

A glucagon test is a lab test to measure the amount of glucagon, a hormone produced by the pancreas, in a patient's blood. A doctor may order this test in cases of suspected pancreatic or pituitary gland malfunction to learn more about a patient's hormone levels. Patients may need to fast before the test, and the doctor will provide more information on how to prepare for the glucagon test in cases where this is necessary. Test results may take several hours to days, depending on where the test is performed.

The pancreas use glucagon to control blood sugar. When blood sugar levels drop, the pancreas produce more of this hormone, triggering the liver to release stored glucose into the bloodstream to stabilize blood sugar levels. A patient with low blood sugar, warning signs of diabetes, or unusual weight loss may be a candidate for a glucagon test. A doctor can also order it if he suspects that a patient's pituitary gland is not functioning right, as this will have an impact on pancreatic function.

In the test, a nurse or technician takes a sample of blood for analysis in a lab. With a fasting glucagon test, the patient cannot eat or drink right before the test, to get a sample of the hormone level when blood sugar is low and the hormone should be high. Nurses may conduct a series of tests after offering food to the patient to see how levels change in response to consuming dietary sugars. This test can be uncomfortable, as low blood sugar may make patients feel irritable, restless, or tired.

Normal glucagon test results will show around 50 to 100 picograms per milliliter of this hormone. It is important to be aware that different labs use their own references, and results may vary between labs. If the test is being repeated, it is advisable to have it done at the same lab facility. Otherwise, variations between results might be attributable to different reference samples and lab techniques, instead of an actual change in the patient's condition.

At the same time a doctor requests a glucagon test, she may also ask the patient to consider other testing for hormones like insulin, depending on the reason for the test. This will require drawing additional blood samples. As always when a lab test is ordered, if a patient is not sure about why the test has been requested, he can ask for clarification and discuss the goal of testing, possible results, and what the next step in treatment might be, depending on the nature of the results.