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Official Description

Glucagon tolerance test

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The glucagon tolerance test, identified by CPT® Code 82946, is a laboratory procedure designed to assess the body's response to glucagon, a hormone that plays a critical role in glucose metabolism. This test measures the levels of glucose and lactate in the blood after glucagon administration. Glucagon is produced by the pancreas and functions to elevate blood sugar levels by prompting the liver to release glycogen, a stored form of glucose, through a process known as glycogenolysis. The glucagon tolerance test is particularly useful in the evaluation and diagnosis of glycogen storage diseases, such as von Gierke's disease and Cori's disease, which are characterized by the body's inability to properly store and utilize glycogen. Prior to undergoing the test, patients are required to fast for a minimum of 14 hours to ensure accurate baseline measurements. During the procedure, an intravenous (IV) line may be established, which can be reported separately, to facilitate the administration of glucagon and the collection of blood samples. Blood samples for glucose and lactate levels are collected at specified intervals—30, 60, 90, and 120 minutes post-injection—either from the IV line or through a separately reportable venipuncture. The analysis of serum or plasma for glucose and lactate is conducted using a quantitative enzymatic method, providing essential data for the assessment of the patient's metabolic response to glucagon.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The glucagon tolerance test is indicated for the evaluation of specific metabolic disorders, particularly those related to glycogen storage. The following conditions may warrant the performance of this test:

  • Glycogen Storage Diseases The test is utilized to differentiate or diagnose glycogen storage diseases, including von Gierke's disease and Cori's disease, which affect the body's ability to store and mobilize glycogen effectively.

2. Procedure

The glucagon tolerance test involves several key procedural steps to ensure accurate measurement of glucose and lactate levels following glucagon administration. The procedure is as follows:

  • Preparation Prior to the test, the patient must fast for a minimum of 14 hours to establish baseline glucose and lactate levels. This fasting period is crucial for obtaining reliable results.
  • IV Line Placement An intravenous (IV) line may be established to facilitate the administration of glucagon and the collection of blood samples. This step may be reported as a separately identifiable procedure.
  • Administration of Glucagon Glucagon is administered either via IV push or intramuscularly (IM) to stimulate the liver's glycogenolysis process. The method of administration should be documented appropriately.
  • Blood Sample Collection Blood samples for glucose and lactate levels are drawn at specific intervals—30, 60, 90, and 120 minutes post-injection. These samples can be obtained from the established IV line or through a separately reportable venipuncture.
  • Laboratory Testing The collected serum or plasma samples are then tested for glucose and lactate levels using a quantitative enzymatic method, which provides precise measurements necessary for evaluating the patient's metabolic response to glucagon.

3. Post-Procedure

After the glucagon tolerance test is completed, patients may be monitored for any immediate reactions to the glucagon administration. It is important to observe the patient for signs of hypoglycemia or other adverse effects. The results of the test will be analyzed and interpreted by the healthcare provider, who will discuss the findings with the patient and determine any further diagnostic or therapeutic steps based on the outcomes of the test.

Short Descr GLUCAGON TOLERANCE TEST
Medium Descr GLUCOSE TOLERANCE TEST
Long Descr Glucagon tolerance test
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) No
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE 1
CCS Clinical Classification 233 - Laboratory - Chemistry and Hematology
Date
Action
Notes
Pre-1990 Added Code added.
Code
Description
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