Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic. An elastic band is placed around the upper arm to apply pressure and cause the vein to swell with blood.

A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the band is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.

In infants or young children:
The area is cleansed with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any bleeding.

Radioimmunoassay (RIA) is a specific laboratory technique.

• Infant test or procedure preparation (birth to 1 year)
• Toddler test or procedure preparation (1 to 3 years)
• Preschooler test or procedure preparation (3 to 6 years)
• Schoolage test or procedure preparation (6 to 12 years)
• Adolescent test or procedure preparation (12 to 18 years)

Glucagon levels may be measured in persons who show symptoms of mild diabetes, unexplained weight loss, or a particular skin rash (necrolytic migratory erythema).

Glucagon is a hormone that is produced by cells in the pancreas. It helps to regulate blood sugar levels. As the level of blood sugar is decreased, the pancreas releases more glucagon, and vice versa. The hormone acts by stimulating the liver to release glucose.

In a rare syndrome, a pancreatic tumor can produce excess glucagon.

Abnormal glucagon levels may indicate:

• Pancreatic tumor-- glucagonoma (glucagon-secreting tumor)
• Multiple endocrine neoplasia (MEN) I

• Excessive bleeding
• Fainting or feeling lightheaded
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)
• Multiple punctures to locate veins