Test Overview
Test Methodology

Anion Gap is calculated using the sodium, chloride and CO2 results on serum. The formula for calculating the anion gap is: Sodium - (Chloride + CO2) = Anion Gap
See the Sodium, Chloride and CO2 individual tests.

Test Usage

Anion Gap is automatically performed with the following panel tests: Electrolyte Panel (LYTES), Renal Function Panel (RENAL), Basic Metabolic Panel (BASIC) and/or Comprehensive Panel (COMP). It is not available as an individual test. Anion Gap is a calculated test using the sodium, chloride and CO2 results on serum. The formula for calculating is: Sodium - (Chloride + CO2) = Anion Gap

The primary clinical use of the anion gap is to assess acid-base disturbances in patients, particularly metabolic acidosis. A marked increase in anion gap (>25 mmol/L) is almost always evidence of metabolic acidosis. Increased anion gap results can be caused by renal failure, diabetic ketoacidosis, starvation, lactic acidosis, ethylene glycol intoxication and methanol intoxication. Reduced anion gap results are less common. Low anion gap can be associated with hypoalbuminemia, myeloma, and lithium intoxication. Laboratory error in measurement of any of the three components of the calculation (Sodium, chloride or CO2) can invalidate the anion gap result.

Reference Range *

4 - 12 mmol/L

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details
Days Set Up
Daily, 24 hours
Analytic Time

Refer to handbook entry for Electrolyte Panel (LYTES), Renal Function Panel (RENAL), Basic Metabolic Panel (BASIC) or Comprehensive Panel (COMP)

Soft Order Code
AGAP
MiChart Code
Anion Gap
Laboratory
Chemical Pathology
Section
Automation
Specimen Requirements
Collection Instructions

Refer to handbook entry for Electrolyte Panel (LYTES), Renal Function Panel (RENAL), Basic Metabolic Panel (BASIC) or Comprehensive Panel (COMP)

Yellow Top Tube
Normal Volume
Refer to handbook entry for Electrolyte Panel (LYTES), Renal Function Panel (RENAL), Basic Metabolic Panel (BASIC) or Comprehensive Panel (COMP)
Minimum Volume
Refer to handbook entry for Electrolyte Panel (LYTES), Renal Function Panel (RENAL), Basic Metabolic Panel (BASIC) or Comprehensive Panel (COMP)
Billing
Resources