Name of the Procedure:

Glucagon Tolerance Test Panel for Pheochromocytoma

• Commonly referred to as: Glucagon Stimulation Test
• Technical term: Glucagon Tolerance Panel

Summary

The Glucagon Tolerance Test Panel for Pheochromocytoma measures the body's response to glucagon, a hormone that raises blood sugar levels. By measuring the levels of catecholamines (e.g., adrenaline and noradrenaline) before and after glucagon administration, medical professionals can evaluate the function of the adrenal glands especially in the context of diagnosing pheochromocytoma.

Purpose

This diagnostic test is primarily used to identify pheochromocytoma, a rare tumor of the adrenal gland that can cause excessive production of catecholamines. The goal is to determine if there is an abnormal increase in catecholamines when glucagon is administered, indicating the potential presence of pheochromocytoma.

Indications

• Persistent high blood pressure unresponsive to typical treatments
• Symptoms such as rapid heartbeat, severe headaches, excessive sweating, and tremors
• Family history of pheochromocytoma or genetic conditions associated with it

Preparation

• Patients may be asked to fast for 8–12 hours prior to the test.
• Some medications may need to be paused, as instructed by the doctor.
• Baseline blood tests to measure catecholamine levels may be conducted.

Procedure Description

1. Pre-Test Preparation:

   • The patient will be seated or lying down for a baseline blood draw.
   • An intravenous (IV) line may be set up for blood sample collection.

2. Glucagon Administration:

   • A measured dose of glucagon is injected into the patient.

3. Monitoring and Blood Draws:

   • Blood samples are taken at specific intervals (generally at baseline, then at 1, 2, and sometimes 3 hours post-injection) to measure the levels of catecholamines.

4. Catecholamine Measurement:

   • Blood samples are analyzed in the lab using the Catecholamines, fractionated (CPT code: 82384 x 2) test.

Duration

• The entire procedure generally takes about 2–3 hours.

Setting

• The procedure is performed in a hospital or specialized outpatient clinic equipped for diagnostic testing.

Personnel

• The test is conducted by a nurse or lab technician, often under the supervision of an endocrinologist or medical specialist.
• A lab technician will process and analyze the blood samples.

Risks and Complications

• Common: Mild discomfort at the injection or blood draw site.
• Rare: Severe blood pressure changes or reactions to glucagon, which are usually managed by the attending medical staff.

Benefits

• Accurate diagnosis of pheochromocytoma, leading to appropriate management and treatment.
• Early detection aids in preventing complications associated with untreated adrenal tumors.

Recovery

• Patients can usually return to normal activities immediately after the test.
• Any specific follow-up care will be advised by the doctor based on the results.

Alternatives

• 24-hour urine collection for catecholamines and metanephrines.
• Imaging studies like MRI or CT scans to identify adrenal gland abnormalities.
• Each alternative has its own pros and cons regarding accuracy, convenience, and patient comfort.

Patient Experience

• Patients may feel anxious about the injections and blood draws, but the procedure is generally well-tolerated.
• Pain management and comfort measures include topical anesthetics at the draw site and assurance from the medical staff about the test's safety.