The Procalcitonin (PCT) test is used to assess the presence of systemic or severe bacterial infections, particularly in cases of suspected sepsis. It is recommended to perform this test when the patient exhibits signs indicative of sepsis, such as clammy and sweaty skin, chills, high fever, severe pain, rapid breathing, palpitations, confusion, or reduced urine output. The PCT test may also be appropriate in specific infections like pneumonia, meningitis, and severe urinary tract infections. Furthermore, it is considered an important indicator for monitoring and guiding the effectiveness of antibiotic treatment.