Abstracts

Rationale: Previous studies have shown that carbamazepine (CBZ) may cause significant hyponatremia.  It is unclear whether the hyponatremia is sustained and if the initial post carbamazepine Na+ level was predictive of the future Na+ levels. Most previous reports did not report pre CBZ Na+ concentrations. Methods: Retrospective clinical data in the Epic Electronic Health Record were extracted from the University of Minnesota’s Clinical Data Repository. Data on Na+ levels were collected in patients who were treated with CBZ in a tertiary medical center. ANOVA was applied to compare mean measurement values between the five Post-CBZ Na+ levels and the Pre-CBZ Na+ levels in the included patient cohorts.  Patients were included in the study if their Na+ levels were available before and after CBZ was started.  Na+ levels were measured at least 5 times post CBZ use in each patient. Results: We identified 981 patients who were treated with carbamazepine at outpatient and/or inpatient settings.  We compared pre-CBZ sodium levels with 1st to 5th Na levels and among the 1st to 5th Na levels after CBZ was started.  Post-CBZ Na+   levels were lower than the pre-CBZ Na+ levels (Pre CBZ = 140.1; 1st Post = 139.5; 2nd Post = 139.3; 3rd Post = 139.4; 4th Post = 139.1; 5th Post = 139.0) (p < 0.0001)  Post-CBZ Na+ levels were also compared among each measurements and with pre-CBZ Na+ levels in this group of patients.As a group, the 1st post CBZ Na+ level was predictive of the future Na+ levels Conclusions: This is the first study in which pre-CBZ Na+ levels were available for a large population. 1st post CBZ Na+ level was predictive of future Na+ levels in patients who were treated with CBZ. Funding: None