Definition & Meaning of "anion gap"

What is an "anion gap"?

An anion gap is a blood test measurement used to help identify the cause of an imbalance in the body’s acid-base levels. It calculates the difference between positive and negative particles in the blood. Positive particles include sodium, while negative particles include chloride and bicarbonate. Bicarbonate is a substance that helps prevent the blood from becoming too acidic. A normal anion gap helps doctors understand if the acid-base imbalance is due to an increase in acids or a loss of bicarbonate.