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Test Code N/Aautomatically calculated when sodium, chloride and CO2 are ordered
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.
Anion GAP is calculated as follows: (Sodium ) – (Chloride + CO2)
1.0 mL serum (0.5 mL minimum) collected in serum separator tube (SST/Tiger Top)
Refrigerated (ship on frozen cold packs)
Refrigerated: 7 days
- Low: <3 mmol/L
- Normal: 3-16 mmol/L
- High: >16 mmol/L
- 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 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.