Background Procalcitonin (PCT) is a biomarker that shows good sensitivity and specificity in identifying septic patients. Methods This study investigated the diagnostic accuracy of PCT in a community hospital setting and how it compared to that of lactic acid. It explored the impact on patient care before and after PCT implementation regarding costs and length of stay. Two comparative groups were analyzed using an exploratory descriptive case–control study with data from a 19-month period after PCT implementation and a retrospective quasi-experimental study using a control group of emergency department patients diagnosed with sepsis using data before PCT implementation. Results Post-procalcitonin implementation samples included 165 cases and pre-procalcitonin implementation sample included 69 cases. From the 165 sepsis cases who had positive blood cultures, PCT had a sensitivity of 89.7%. In comparison, lactic acid's sensitivity at the current cutoff of 18.02 mg/dL (2.0 mmol/L) was 64.9%. There was a 32% decrease in median cost before and after PCT implementation, even with the length of stay remaining at 5 days in both time periods. Conclusions There was a significant decrease after the implementation of PCT in cost of hospitalization compared to costs before implementation. This cost is highly correlated with length of stay; neither the hospital nor the intensive care unit length of stay showed a difference with before and after implementation. There was a positive correlation between lactic acid and PCT values. PCT values had a higher predictive usefulness than the lactic acid values.