Procalcitonin (PCT) Test: A Key Biomarker in Detecting Severe Bacterial Infections
Introduction P rocalcitonin (PCT) is a small protein made by certain cells in the body, mainly in the thyroid gland , lungs, and intestines. Normally, healthy people have almost undetectable amounts of PCT in their blood. PCT has emerged as one of the most reliable biomarkers for the early detection of systemic bacterial infections and sepsis. Initially identified by Le Moullec in 1984 as a 116–amino acid residue, its clinical importance was not recognized until 1993, when Assicot and colleagues demonstrated a strong correlation between elevated serum PCT levels and bacterial infections , particularly sepsis confirmed by blood cultures. Unlike other inflammatory markers such as C-reactive protein (CRP) , which lack the specificity to differentiate between bacterial and non-bacterial infections, PCT has proven to be more precise. It remains low in viral infections and decreases once effective antibiotic treatment begins, making it a useful tool in guiding antimicrobial therapy. T...