The utility of routine electrolytes and blood cell counts in patients with chest pain

The objective of the study was to determine whether the routine screening laboratory tests, electrolytes (E) and hemoglobin and hematocrits (H/H), could have been safely avoided in ED patients presenting with chest pain. Retrospective case series over a 3-month period were reviewed. Acceptable indications for E and H/H test ordering were prospectively developed using American College of Emergency Physicians (ACEP) guidelines. Charts were reviewed to determine whether any indications were present, whether the E and H/H laboratory tests were abnormal, and whether the abnormal test affected treatment or disposition. Patients were excluded if they had an abnormal electrocardiogram (ECG) indicating ischemia or electrolyte abnormality. This resulted in 191 patients meeting inclusion criteria. Sixty-eight patients did not have any criteria for ordering E or H/H. Of these, only one (1.5%) had an abnormal laboratory test. The sensitivity of the guidelines for predicting an abnormal laboratory test was 96% (95 CI, 82 to 100%) and the specificity was 46% (95CI, 38 to 54%). There were no interventions, consultations, or any change in disposition based on E or H/H testing in these patients. Of the 123 patients that met at least one criteria for ordering laboratory tests, 27 (18%) had an abnormal result. It was concluded that practice guidelines may reduce the number of E and H/H tests ordered without missing significant abnormalities. A prospective trial is needed to validate these findings.