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Test Code AGAP Calculation Anion Gap Calculation, Serum or Plasma

Important Note

Note: Anion Gap cannot be ordered separately. This test is a calculated value that is included in the Basic Metabolic Panel (BMP), BMP with Ionized Calicum (BMPICA), Comprehensive Metabolic Panel (COMP), Electrolyte (LYTE) and Renal Panel (RENAL).  

Specimen Requirements

Container Type:

Optimal: Gold or Mint*

*For STAT requests

Acceptable: Red or Green
Optimal Collection Volume: 

4.5mL; full tube
Minimum Volume:
  • Adults: 1 mL whole blood
  • Neonates: 1 microtainer (400-600 uL)
Collection Instructions:

Gently invert the sample 5-6 times after collection.
Specimen Transport:

Refrigerate
Processing Instructions: 

1. If serum, allow the specimen to clot for 30 minutes.

2. Centrifuge specimen within 2 hours of collection.

3. After centrifugation, specimen tubes without a gel barrier should have the serum or plasma aliquoted to a false bottom container.

4. Keep serum or plasma refrigerated until testing can be performed.

Specimen Stability

Specimen Type Temperature Time

Serum*

Refrigerated

7 days

Room Temperature

7 days

*Note: Heparinized plasma in gel separator tubes is less stable than serum and is only suitable for add-on testing up to 2 days following sample collection.

Specimen Rejection Criteria

Hemolysis

Mild OK; Moderate OK; Gross Reject

Lipemia

Mild OK; Moderate OK; Gross Reject

Icterus

Mild OK; Moderate OK; Gross Reject

Other

Quantity not sufficient

Useful For

The anion gap calculation used at Bronson is with "without K+" formula effective 5/29/2019.

i.e. Na - (Cl + CO2).     

Methodology

Na and Cl: Roche Cobas - Ion-specific electrode

 

CO2: Roche Cobas - Spectrophotometric

Reference Ranges

7-16 mmol/L

Interpretive

Increased anion gaps can be seen in disease states such as uremia with retention of anions, Ketotic states (diabetes or starvation), Toxin ingestion (methanol, salicylate, ethylene glycol, lactic acidosis, or dehydration

 

Decreased anion gaps can be caused by hypoalbuminemia or protein abnormalities such as multiple myeloma.

Day(s) Performed

24/7

Expected TAT

Same day

Performing Laboratory

Bronson Laboratory, Chemistry - Kalamazoo, Battle Creek, Paw Paw, South Haven

Sample Retention Time

7 days

LOINC Code

1863-0