Objectives: This review examines the role of serum procalcitonin (PCT) as a diagnostic marker for sepsis and its potential implications in anaphylaxis. Elevated PCT levels, often associated with bacterial infections, can complicate diagnosis when seen in anaphylaxis, especially when clinical features overlap with sepsis. Methods: We conducted a literature review on PCT in anaphylaxis to highlight key patterns and present two cases of anaphylactic shock initially misdiagnosed as sepsis due to elevated PCT levels. Results: The review supports that elevated PCT can occur in anaphylaxis, stressing the need for thorough patient history and symptom evaluation. In both cases, elevated PCT led to initial sepsis diagnoses, but further investigation identified anaphylaxis triggered by sulfamethoxazole/trimethoprim (SMX/TMP). Conclusions: These findings emphasize the need for considering anaphylaxis in differential diagnoses when elevated PCT levels are observed. Increased awareness of PCT's potential association with allergic drug reactions is essential to ensure timely recognition, avoid diagnostic delays, and improve patient outcomes.
Keywords: allergic drug reaction; allergy; anaphylactic shock; anaphylaxis; differential diagnosis; misdiagnosis; procalcitonin; sepsis; sulfamethoxazole; trimethoprim.