Hyperchloraemic acidosis: another misnomer?

OBJECTIVE

To review the term hyperchloraemic acidosis.

DATA SOURCES: Articles and reviews from peer reviewed journals on acid-base physiology.

SUMMARY OF REVIEW: The concept of hyperchloraemic acidosis is well established in medicine and regularly taught to medical students. Unfortunately, it is yet another medical misnomer. Hyperchloraemic acidosis is only likely to exist with normal plasma sodium concentrations. This is because the acidosis is due to a decreased strong-ion-difference rather than the hyperchloraemia alone. If hyponatraemia is present, an identical acidosis can exist without hyperchloraemia; or if hypernatraemia is present there may be hyperchloraemia without acidosis. Even those who cling to the bicarbonate centred approach to acid-base physiology should recognise that describing acid-base changes in terms of chloride alone is less meaningful than considering both the strong cations and the strong anions. For those clinicians, using the Stewart approach the value of the terms "strong ion acidosis" and "strong ion alkalosis" should be readily apparent.

CONCLUSIONS

The use of the term hyperchloraemic acidosis is a misnomer as the chloride ion may be elevated or depressed in the absence of an acid bade abnormality.