During a recent shift, a question arose regarding whether to use the measured or corrected sodium to calculate the anion gap in a critically ill patient with DKA.
Recall that the anion gap provides an estimation of unmeasured anions - in this case acetoacetate and beta-hydroxybutyrate.
Glucose is electrically neutral and therefore does not affect the anion gap.
When calculating the anion gap in a patient with DKA, use the actual (measured) serum Na, rather than the corrected value.