Delta ratio Assessment <0.4Hyperchloraemic normal anion gap acidosis 0.4 – 0.8 Combined high AG and normal AG acidosis Note that the ratio is often <1 in acidosis associated with renal failure 1 - 2 Uncomplicated high-AG acidosis Lactic acidosis: average value 1.6 DKA more likely to have a ratio closer to 1 due to urine ketone loss (if patient not dehydrated) >2 Pre-existing increased [HCO 3 - ]: concurrent metabolic alkalosis pre-existing compensated respiratory acidosis ratio = Anion gap/[HCO 3 - ] = (AG – 12)/(24 - [HCO 3 - ])
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