Delta-Delta Ratio Calculator

About this calculator

The delta-delta ratio (delta gap / delta ratio) is calculated as (anion gap − 12) / (24 − serum bicarbonate), comparing how much the anion gap has risen against how much bicarbonate has fallen from their normal values, to check whether a high anion gap metabolic acidosis is "pure" or accompanied by a second acid-base disorder.

Emergency physicians, intensivists and nephrologists use the ratio at the bedside: a ratio near 1 suggests a simple high anion gap acidosis, below 1 suggests a co-existing normal anion gap (hyperchloremic) acidosis, and above 2 suggests a concurrent metabolic alkalosis or pre-existing elevated bicarbonate — a distinction that changes fluid and electrolyte management in conditions like diabetic ketoacidosis with vomiting.