What is a Procalcitonin Test?
A procalcitonin test measures the level of procalcitonin in your blood. Normally, you have very low levels of procalcitonin in your blood. But if you have a serious bacterial infection, the cells in many parts of your body will release procalcitonin into your bloodstream. A high level of procalcitonin in your blood may be a sign of a serious infection or sepsis.
Sepsis (also called septicemia) is your immune system's extreme response to an infection, usually from bacteria. Sepsis happens when an infection you already have spreads into your bloodstream and triggers a chain reaction throughout your body. It causes inflammation and blood clots. Without quick treatment, sepsis can rapidly lead to tissue damage, organ failure, or even death.
Infections that lead to sepsis most often start in your lungs, urinary tract, skin, or digestive system. A procalcitonin test can help your health care provider diagnose if you have sepsis from a bacterial infection or if you have a high risk of developing sepsis. This may help you get the right treatment quickly before your condition worsens.
Other names: PCT test
What is it used for?
A procalcitonin test is mostly used if you are seriously ill and your provider thinks you may have a systemic infection (an infection that affects your entire body). The test helps find out whether bacteria or a virus is causing your infection. For example, a procalcitonin test can help tell the difference between bacterial and viral pneumonia. This matters because antibiotics may help bacterial infections, but not viral infections.
The test may be used to help:
- Diagnose or rule out a bacterial infection and/or sepsis
- Find out how serious a sepsis infection may be
- Make treatment decisions
- Monitor how well treatment is working
- Diagnose kidney infections in children with urinary tract infections
This test is usually used in the hospital for very sick people who are in the emergency room or have already been admitted to the hospital.
Why do I need a procalcitonin test?
You may need this test if you have symptoms of sepsis or a serious bacterial infection that could become sepsis. Symptoms of sepsis include:
- Fever or chills
- Clammy or sweaty skin
- Extreme pain
- Rapid heartbeat
- Shortness of breath
- Low blood pressure
Sepsis is a medical emergency. If your or your loved one has an infection that's not getting better or is getting worse, get medical help right away.
What happens during a procalcitonin test?
A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.
Will I need to do anything to prepare for the test?
You don't need any special preparation for a procalcitonin test.
Are there any risks to the test?
There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.
What do the results mean?
High procalcitonin levels mean that you:
- Most likely have sepsis
- May have a high risk of developing severe sepsis and septic shock, a life-threatening condition when your organs don't get enough blood to work properly
- May have a serious systemic bacterial infection that increases your risk for sepsis
The higher your procalcitonin levels, the higher your risk for sepsis and septic shock.
Moderate to mildly high levels of calcitonin may be sign of:
- The earlier stages of a systemic bacterial infection
- Kidney infection, in children only
- Conditions other than infections, such as tissue damage from trauma, serious burns, recent surgery, severe heart attack
Slightly high levels of procalcitonin mean that you are unlikely to develop sepsis, but they may be a sign of:
- A local bacterial infection, such as a urinary tract infection
- An infection from another cause, such as a virus
- A systemic bacterial infection that is just beginning
If you are being treated for a bacterial infection, decreasing or low procalcitonin levels mean that your treatment is working.
Learn more about laboratory tests, reference ranges, and understanding results.
Is there anything else I need to know about a procalcitonin test?
A procalcitonin test won't show what type of bacteria is causing an infection. To make a full diagnosis, your provider will likely order other tests. But a procalcitonin test does give you important information about your risk for sepsis, so you can start treatment sooner, if needed, and avoid more serious illness.
- AACC [Internet] Washington D.C.; American Association for Clinical Chemistry; c2022. Do We Need Procalcitonin for Sepsis?; 2015 Feb [cited 2022 Apr 19]; [about 2 screens]. Available from: https://www.aacc.org/publications/cln/articles/2015/february/procalcitonin-for-sepsis
- Balci C, Sungurtekin H, Gürses E, Sungurtekin U, Kaptanoğlu, B. Usefulness of procalcitonin for diagnosis of sepsis in the intensive care unit. Crit Care [Internet]. 2002 Oct 30 [cited 2022 Apr 19]; 7(1):85–90. Available from: https://ccforum.biomedcentral.com/articles/10.1186/cc1843
- Centers for Disease Control and Prevention [Internet]. Atlanta: U.S. Department of Health and Human Services; Sepsis; [updated 2021 Aug 19; cited 2022 Apr 19]; [about 1 screen]. Available from: https://www.cdc.gov/sepsis/basic/index.html
- Children's Minnesota [Internet]. Minneapolis (MN): Children's Minnesota; c2022. Chemistry: Procalcitonin; [updated 2020 Dec 7; cited 2022 Apr 19]; [about 4 screens]. Available from: https://www.childrensmn.org/references/lab/chemistry/procalcitonin.pdf
- Cleland DA, Eranki AP. Procalcitonin. [Updated 2021 Aug 11; cited 2022 Apr 21]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2022 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK539794/
- LabCorp [Internet]. Burlington (NC): Laboratory Corporation of America; c2022. Procalcitonin; [cited 2022 Apr 19]; [about 7 screens]. Available from: https://www.labcorp.com/test-menu/33581/procalcitonin
- Mayo Clinic: Mayo Medical Laboratories [Internet]. Mayo Foundation for Medical Education and Research; c1995–2022. Test ID: PCT: Procalcitonin, Serum; [cited 2022 Apr 19]; [about 3 screens].Available from: https://www.mayocliniclabs.com/test-catalog/overview/83169#Clinical-and-Interpretive
- Meisner M. Update on Procalcitonin Measurements. Ann Lab Med [Internet]. 2014 Jul [cited 2022 Apr 19]; 34(4): 263–273. Available from: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4071182
- Merck Manual Professional Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2022. Sepsis and Septic Shock; [reviewed 2021 Sep; cited 2022 Apr 19]; [about 5 screens]. Available from: https://www.merckmanuals.com/home/infections/bacteremia,-sepsis,-and-septic-shock/sepsis-and-septic-shock
- Merck Manual Professional Version [Internet]. Kenilworth (NJ): Merck & Co. Inc.; c2022. Sepsis and Septic Shock; [reviewed 2021 Sep; cited 2022 Apr 19]; [about 8 screens]. Available from: https://www.merckmanuals.com/professional/critical-care-medicine/sepsis-and-septic-shock/sepsis-and-septic-shock
- National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests; [updated 2022 Mar 24; cited 2022 Apr 19]; [about 7 screens]. Available from: https://www.nhlbi.nih.gov/health/blood-tests
- Samsudin I, Vasikaran SD. Clinical Utility and Measurement of Procalcitonin. Clin Biochem Rev [Internet]. 2017 Apr [cited 2022 Apr 21];38(2):59-68. PMID: 29332972; PMCID: PMC5759088.
- Testing.com [Internet]. Seattle (WA): OneCare Media; c2022. Procalcitonin; [modified 2020 Dec 21; cited 2022 Apr 19]; [about 9 screens]. Available from: https://www.testing.com/tests/procalcitonin/