Glucagon is secreted by the cells of the islets of Langerhans in response to decreased blood glucose levels. Its actions are opposed by insulin. Elevated glucagon levels are associated with conditions that produce actual hypoglycemia or a physiological need for greater blood glucose (e.g., trauma, infection, starvation, excessive exercise) and with insulin lack. Thus, elevated glucagon levels may be found in severe or uncontrolled diabetes mellitus, despite hyperglycemia.

• Trauma, infection, starvation, and excessive exercise may lead to elevated levels, as will acute pancreatitis, pheochromocytoma, uncontrolled diabetes mellitus, and uremia.
• Failure to follow dietary restrictions before the test may lead to falsely decreased levels.

• Suspected glucagonoma as indicated by elevated levels (as high as 1000 pg/mL) in the absence of diabetic ketoacidosis, uremia, pheochromocytoma, or acute pancreatitis
• Confirmation of glucagon deficiency related to loss of pancreatic tissue as a result of chronic pancreatitis, pancreatic neoplasm, or surgical resection (Arginine infusion, which normally leads to elevated glucagon levels, may be used for further confirmation of the deficiency state.)
• Suspected renal transplant rejection, as indicated by rising plasma glucagon levels (Glucagon levels may rise markedly several days before serum creatinine begins to rise.)

Nursing Care Before the Procedure

General client preparation is the same as that for any test involving collection of a peripheral blood sample (see Appendix I).

• For this test, the client should fast from foods for 8 hours before the study. Water is permitted.

A venipuncture is performed and the sample is collected in either a green- or a lavender-topped tube, depending on the laboratory performing the test. The sample should be handled gently to avoid hemolysis and sent to the laboratory immediately.

Nursing Care After the Procedure

Care and assessment after the procedure are the same as for any test involving the collection of a peripheral blood sample.

• Resume usual diet as soon as possible after the sample has been obtained.
• Complications and precautions: Assess the test results in relation to insulin and glucose levels.