Cedars-Sinai

Medical Staff Pulse Newsletter

Core Labs Updating Anion Gap Calculation

Beginning Dec. 16, the Core Laboratories within the Department of Pathology and Laboratory Medicine will update the anion gap calculation to include potassium. This calculation normally includes the difference between the major measured cations and anions in blood serum/plasma.

We have historically used the following calculation:

Na - (Cl + HCO3)

Which will now go to:

(Na + K) - (Cl + HCO3)

The update should provide a slightly more accurate estimate of the anion gap. With this update to the calculation, we will also be updating the reference interval from 8-20 mmol/L to 10-20 mmol/L. This change to the reference interval doesn't coincide with the calculation change directly, but rather to current cited sources that include potassium.

If you have questions, contact Kimia Sobhani at kimiasobhani@cshs.org, or Anders Berg, PhD, at anders.berg@cshs.org.