Topiramate and acidosis: a case review questions the usual explanation

Reexamining the available laboratory data

The authors revisited published cases of topiramate-associated acidosis using Stewart’s physicochemical model. Their aim was to reassess the mechanisms based on the available laboratory data, rather than relying on the usual classification.

This was therefore neither a trial comparing treatments nor a follow-up study capable of estimating the frequency of this adverse effect. The review primarily seeks to determine whether the conventional explanation accurately describes the reported abnormalities.

Abnormalities the usual anion gap did not reveal

According to the abstract, all patients with true metabolic acidosis had an increased strong ion gap. This finding suggests an excess of unmeasured anions that the conventional anion gap did not detect.

Hyperchloremia was common, but not universal. The authors also report that the role of chloride had often been misclassified. These observations challenge a uniform description of topiramate-associated acidosis, without establishing the origin of the unmeasured anions.

A normal pH did not always tell the whole story

Several patients had normal pH or bicarbonate levels despite substantial physicochemical abnormalities. The abstract describes mixed disturbances involving respiratory alkalosis and effects related to weak acids.

One illustrative case notably combined an elevated strong ion gap with a normal anion gap in the setting of hypocapnia. The value of this observation lies in its interpretation: apparently reassuring parameters can coexist with a disturbed acid–base balance.

A refined hypothesis, not new management guidance

This reanalysis suggests that the mechanisms associated with topiramate may be more varied than the usual label implies. However, it does not demonstrate that routinely using this analytical method would improve treatment decisions or clinical outcomes.

The abstract provides neither a prospective comparison of diagnostic approaches nor an evaluation of a management strategy. It therefore does not support turning this physiological proposal into a practical recommendation.

What we can take away

This review calls for a more nuanced explanation of topiramate-associated acidosis. It offers a mechanistic lead, not evidence warranting a treatment change.