The Procalcitonin test is popularly known by the name PCT and is highly effective in diagnosing bacterial Sepsis. Procalcitonin is a peptide precursor to the hormone calcitonin and consists of 116 amino acids. It is normally produced by the thyroid gland. The PCT levels increase in the blood due to severe bacterial infection as the immune cells also start producing them. PCT is regarded as the best biomarker for diagnosing severe systemic inflammation, infection and sepsis. This test is also ordered in the case of pneumonia or meningitis and for diagnosing urinary tract infections in children.