Procalcitonin (PCT) in Serum or Plasma

Why Is This Test Done?

Your doctor may order a procalcitonin test to evaluate suspected bacterial infections, such as pneumonia, sepsis, or other serious illnesses. It can also help determine if antibiotics are needed and monitor their effectiveness. In some cases, it may be used alongside other tests to distinguish between bacterial and viral infections.

What Does a High or Low Result Mean?

Elevated procalcitonin levels often indicate a bacterial infection. Very low or normal levels suggest a viral infection or no significant bacterial involvement. However, results can vary based on the severity and type of infection, so they should be interpreted by your healthcare provider in the context of your overall health and symptoms.

How Is the Test Performed?

A blood sample is drawn from a vein, usually in your arm. The blood is then processed to separate serum or plasma, which is sent to a lab for analysis. The test measures the concentration of procalcitonin in the sample using immunoassay methods.

What Are Common Causes of Abnormal Results?

High procalcitonin levels can be caused by bacterial infections (e.g., pneumonia, sepsis), certain cancers (e.g., lung cancer), or inflammatory conditions. Low levels may be seen in viral infections, non-bacterial inflammatory diseases, or during recovery from bacterial infections.