Test Code N/Aautomatically calculated when sodium, chloride and CO2 are ordered
Test Details
Anion Gap
Anion gap is a chemistry calculation using results of an electrolyte panel to determine acid/base balance. This test is most commonly performed in patients who present with altered mental status, unknown exposures, acute renal failure, and acute illnesses.
Methodology
Anion GAP is calculated as follows: (Sodium ) – (Chloride + CO2)
Patient Preparation
None
Preferred Specimen
1.0 mL serum (0.5 mL minimum) collected in serum separator tube (SST/Tiger Top)
Transport Temperature
Refrigerated (ship on frozen cold packs)
Stability
Refrigerated: 7 days
Lab Values
Anion Gap
- Low: <3 mmol/L
- Normal: 3-16 mmol/L
- High: >16 mmol/L
Clinical Significance
Anion Gap
- Elevated level may indicate metabolic acidosis as in diabetic ketoacidosis, lactic acidosis; (rhabdomyolysis) severe muscle break down, kidney failure, aspirin overdose or methanol.
- Low levels very rare. May indicate low serum protein levels possibly due to kidney, liver disorders or malnutrition.
Treatment Options
Anion Gap
- Treatment depends on which electrolyte(s) is out of balance and the extent of that change.
- Identify etiology of elevated Anion GAP.
- Most common symptoms in patients with abnormal anion gap are those who present with altered mental status, unknown exposures, acute renal failure, and acute illnesses.
