(see also ABGs)

The base excess/deficit is a calculated number that represents the amount of base that must be added to restore the blood to a normal pH of 7.4. Normal range is +2 to -2 mEq/L.

Base deficit (acidosis) ← pH 7.4 → Base excess (alkalosis)

The parameter is confusing, in that the terms excess and deficit are sometimes used interchangeably. To be correct, excess (signifying metabolic alkalosis) should be reported as a positive number, and deficit (signifying metabolic acidosis) should be reported as a negative number.