What is anion gap?

The anion gap is the difference between cations and anions in urine, plasma or serum. This gap can be used to diagnose metabolic disorders. If a high anion gap is noted, the lab results are often compared to clinical symptoms and representations. If the patient does not display symptoms of a metabolic disorder, but the anion gap measurement was higher than normal there could have been a lab error. The anion gap test is extremely specific and the gap must be measured immediately after collection. Prolonged waiting can lead to abnormal results.

Normal value range

• Negative Pregnancy Adult: 7 to 16 mmol/L
• Pregnancy Trimester One: 10 to 20 mmol/L
• Pregnancy Trimester Two: 10 to 18 mmol/L
• Pregnancy Trimester Three: 11 to 18 mmol/L