What Is a Procalcitonin Test Used For?

A procalcitonin test is used to detect or rule out sepsis.

Procalcitonin is a peptide (a small chain of amino acids) produced by the body, usually in response to bacterial infections or tissue injury. Procalcitonin levels in the blood may increase when systemic bacterial infections and sepsis are present. A procalcitonin test measures levels of procalcitonin in the blood, and is used to determine if there is bacterial sepsis present, which is a severe, systemic, potentially life-threatening infection. 

A procalcitonin test is used to detect or rule out sepsis, a severe, systemic, potentially life-threatening infection. 

Symptoms of sepsis include:

• Fever
• Chills
• Fast breathing/trouble breathing
• Fast heartbeat 
• Confusion
• Lightheadedness 
• Dizziness
• Cool clammy skin or red flushed skin
• Loss of appetite
• Urinating less than usual
• Skin rashes 
• Belly pain 
• Severe diarrhea with cramping
• Other problems with the heart, kidneys, or brain

A procalcitonin test is used to help determine:

• Whether there is a risk a person’s condition will progress to severe sepsis, septic shock, or death
• If the cause of the infection is bacterial or not
• Whether a secondary bacterial infection has developed in patients with tissue damage due to trauma or surgery, burns, or a viral illness such as pneumonia
• What antibiotic treatments are needed or to monitor the effectiveness of treatments already administered 
• If a kidney infection is present in children with urinary tract infections (UTIs)

Other tests that may be ordered along with a procalcitonin test include:

• Complete blood count (CBC)
• C-reactive protein (CRP)
• Cultures (e.g., blood culture, urine culture)
• Blood gases
• Lactate
• Cerebrospinal fluid (CSF) analysis

A procalcitonin test is performed by a regular blood draw and is calculated in a lab. Results and ranges are indicated as follows:

• Normal: 0 to 0.05 micrograms per liter (µg/L)
• Low risk of sepsis: less than 0.5 µg/L
• Possible sepsis: between 0.5 µg/L and 2 µg/L
• Moderate to high risk of sepsis: 2 µg/L and 10 µg/L
• Severe sepsis: 10 µg/L or greater

Complications of a procalcitonin test are typically minor and the same as they would be for any blood draw, and may include:

• Pain at the site of injection
• Bleeding
• Infection
• Swelling
• Bruising
• Blood clot formation
• Nerve damage
• A hard lump