Procalcitonin
- Also Known As:
- PCT

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.At a Glance
Why Get Tested?
To help diagnose sepsis if you are critically ill and to help determine your risk of progressing to severe sepsis and septic shock; to help identify serious bacterial infections and to distinguish between bacterial and non-bacterial conditions; to help guide antibiotic treatment
When To Get Tested?
When you are seriously ill and have signs and symptoms of a systemic infection or sepsis; when you have signs and symptoms that may be due to a bacterial infection and your healthcare practitioner wants to determine whether antibiotics would be effective; at intervals to monitor effectiveness of antibiotic treatment
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
None
You may be able to find your test results on your laboratory’s website or patient portal. However, you are currently at Testing.com. You may have been directed here by your lab’s website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab’s website or portal, or contact your healthcare practitioner in order to obtain your test results.
Testing.com is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.
The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.
If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.
Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called “normal” values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.
While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are “within normal limits.”
For more information, please read the article Reference Ranges and What They Mean.
What is being tested?
Procalcitonin is a substance produced by many types of cells in the body, often in response to bacterial infections but also in response to tissue injury. The level of procalcitonin in the blood can increase significantly in systemic bacterial infections and sepsis. This test measures the level of procalcitonin in the blood.
Sepsis is the body’s serious, overwhelming and sometimes life-threatening inflammatory response to a bacterial infection. Normally, a person’s immune system targets an infection, confining the bacteria and limiting its response to the infected area. However, some infections may begin in one site of the body and then spread to the blood (bacteremia) and possibly to other sites. With sepsis, the body produces a generalized inflammatory response to the infection. This can cause a significant rise or fall in body temperature, increased heart rate and breathing rate, and a decrease in blood pressure. If not treated successfully, sepsis can progress to severe sepsis.
Other conditions can also increase procalcitonin in the blood, but usually procalcitonin is only mildly to moderately elevated. Examples of these conditions include tissue damage due to events such as trauma, surgery, pancreatitis, burns, cardiogenic shock (related to a heart attack), acute organ transplant rejection, and kidney involvement in urinary tract infections in children.
The procalcitonin test is useful in helping to detect sepsis and severe bacterial infections in the early stages and to distinguish between a bacterial infection and other non-bacterial causes of signs and symptoms in a seriously ill person.
Common Questions
Related Content
On This Site
Tests: C-Reactive Protein, Complete Blood Count, Blood Culture, CSF Analysis
Elsewhere On The Web
MedlinePlus Medical Encyclopedia: Sepsis
MedlinePlus Medical Encyclopedia: Septic shock
American Lung Association: Pneumonia
Centers for Disease Control and Prevention: Sepsis
Sepsis Alliance
National Institute of General Medical Sciences: Sepsis Fact Sheet
View Sources
Sources Used in Current Review
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Kaplan, L. (2016 August 16 Updated). Systemic Inflammatory Response Syndrome Workup. Medscape Drugs and Diseases. Available online at http://emedicine.medscape.com/article/168943-workup#showall. Accessed on 1/22/17.
Douglas, D. (2016 March 16). Procalcitonin Guidance Curbs Antibiotic Use in Critically Ill. Reuters Health Information. Available online at http://www.medscape.com/viewarticle/860394. Accessed on 1/22/17.
Lin, J. and Yap, S. (2015 November 24 Updated). Procalcitonin. Medscape Drugs and Diseases. Available online at http://emedicine.medscape.com/article/2096589-overview. Accessed on 1/22/17.
(2016 September Updated). Sepsis. ARUP Consult. Available online at https://arupconsult.com/content/sepsis. Accessed on 1/22/17.
Cunha, B. (2016 March 18 Updated). Bacterial Sepsis Workup. Medscape Drugs and Diseases. Available online at http://emedicine.medscape.com/article/234587-workup#showall. Accessed on 1/22/17.
(February 2015) Sutirtha Chakraborty, MD. Do We Need Procalcitonin for Sepsis? Ask the Expert, Clinical Laboratory News. Available online at https://www.aacc.org/publications/cln/articles/2015/february/procalcitonin-for-sepsis. Accessed February 2017.
Wacker C, et al. Procalcitonin as a diagnostic marker for sepsis: a systematic review and meta-analysis. The Lancet Infectious Diseases. Volume 13, No. 5, p426–435, May 2013. Available online at https://www.ncbi.nlm.nih.gov/pubmed/23375419. Accessed February 2017.
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Sources Used in Previous Reviews
Yealy, D. et. al. (2009 September 8). Blood Test Narrows Down Need for Antibiotics. MedlinePlus HealthDay News [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/news/fullstory_89106.html. Accessed October 2009.
Brown, A. (2009 June 19). Procalcitonin Testing May Shorten Antibiotic Course in ICU Patients. Medscape Today from Reuters Health Information [On-line information]. Available online at http://www.medscape.com/viewarticle/704569. Accessed October 2009.
Boggs, W. (2009 January 7). Procalcitonin Levels Lower With Blood Stream Infection in Setting of Prior Sepsis. Medscape Today from Reuters Health Information [On-line information]. Available online at http://www.medscape.com/viewarticle/586453. Accessed October 2009.
(2008 December 5). Procalcitonin Discriminates Between Bacterial and Aseptic Meningitis in Children. Medscape Today from Reuters Health Information [On-line information]. Available online at http://www.medscape.com/viewarticle/584813. Accessed October 2009.
Barclay, L. (2009 February 9). Procalcitonin, CRP May Predict Serious Bacterial Infection in Febrile Infants. Medscape Medical News [On-line information]. Available online at http://www.medscape.com/viewarticle/588042. Accessed October 2009.
Barclay, L. (2009 September 16). Procalcitonin Measurements May Reduce Rates of Antibiotic Use for Lower Respiratory Tract Infections. Medscape Medical News [On-line information]. Available online at http://www.medscape.com/viewarticle/708991. Accessed October 2009.
Bennett, N. J. et. al. (Updated 2008 June 26). Bacteremia: Differential Diagnoses & Workup. eMedicine [On-line information]. Available online at http://emedicine.medscape.com/article/961169-diagnosis. Accessed October 2009.
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Clarke, W., Editor (© 2011). Contemporary Practice in Clinical Chemistry 2nd Edition: AACC Press, Washington, DC. Pg 519.
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