Gaps in the anion gap.

OBJECTIVE

To review limitations of the use of serum anion gap in clinical practice.

DATA SOURCES

Original reports and reviews.

STUDY SELECTION

Sources containing the most recent pertinent information.

DATA SYNTHESIS

Theoretical and practical limitations beset the use of serum anion gap. Awareness of these limitations reduces but does not eliminate wrong diagnoses based on the anion gaps.

CONCLUSIONS

Serum anion gap has a limited value in the differential diagnosis of acid-base disorders and can be misleading.