At a Glance
Why Get Tested?
To help diagnose sepsis in a person who is critically ill; to help determine the risk of severe sepsis leading to septic shock in a person who has sepsis; to distinguish bacterial from non-bacterial infections
When to Get Tested?
When someone is seriously ill and a doctor wants to distinguish between sepsis and other causes of the illness; to help guide treatment in a patient with sepsis
Sample Required?
A blood sample drawn from a vein in your arm
Test Preparation Needed?
None
The Test Sample
What is being tested?
This test measures the amount of procalcitonin in the blood. Procalcitonin is a precursor to the thyroid hormone calcitonin. It is normally produced by special cells in the thyroid gland called C-cells and is present in low levels in the blood. However, it may also be made by other cells in the body when stimulated by an intense stressor, in particular systemic bacterial infection (sepsis; as opposed to local bacterial infections). Other stressors include infection from other causes, tissue damage due to events such as trauma, surgery, pancreatitis, burns, cardiogenic shock – related to a heart attack – and acute organ transplant rejection.
Levels of procalcitonin in the blood increase rapidly and significantly when a person has sepsis. They are not as markedly elevated when a person has a viral infection or other illnesses, as noted above, which may present with the same symptoms as sepsis. This gives the procalcitonin test the potential to be used to help detect the presence of a severe bacterial infection in its early stages and to distinguish between a bacterial infection and another cause of a seriously ill person's symptoms.
How is the sample collected for testing?
A blood sample is obtained by inserting a needle into a vein in the arm.
NOTE: If undergoing medical tests makes you or someone you care for anxious, embarrassed, or even difficult to manage, you might consider reading one or more of the following articles: Coping with Test Pain, Discomfort, and Anxiety, Tips on Blood Testing, Tips to Help Children through Their Medical Tests, and Tips to Help the Elderly through Their Medical Tests.
Another article, Follow That Sample, provides a glimpse at the collection and processing of a blood sample and throat culture.
Is any test preparation needed to ensure the quality of the sample?
No test preparation is needed.
The Test
How is it used?
The procalcitonin test is relatively new, but its utilization is increasing. Recent studies have shown that it has promise in helping to evaluate the risk that a seriously ill person is developing a systemic bacterial infection. It has primarily been studied in people who present to Emergency Departments or who are admitted to intensive care units (ICUs) and who have symptoms that may be due to sepsis. The procalcitonin test has been approved by the U.S. FDA (Food and Drug Administration) for use in conjunction with other laboratory findings and clinical assessments to assist in the risk assessment of critically ill people for progression to severe sepsis and septic shock. For diagnostic purposes, it is best used during the first day of presentation. It may be used later on to monitor the response to treatment.
Procalcitonin may sometimes be ordered, along with other tests such as a CRP (C-reactive protein), blood culture, CBC (Complete Blood Count), or CSF (cerebrospinal fluid) analysis to help detect or rule out sepsis, bacterial meningitis, or bacterial pneumonia in those who are seriously ill and in children with a fever of unknown origin.
Occasionally, a procalcitonin test may be ordered at intervals to monitor the effectiveness of antimicrobial treatment.
When is it ordered?
The procalcitonin test may be ordered along with other tests, when a seriously ill person has symptoms that suggest that they may have a systemic or severe bacterial infection. When used, it is typically ordered as an early detection tool, within the first day of hospital admission.
Complications of sepsis may include:
- Chills, fever
- Nausea
- Rapid breathing, rapid heartbeat
- Confusion
- Decreased urine output
More severe symptoms include inflammation throughout the body and formation of many tiny blood clots in the smallest blood vessels. One or more organs may begin to stop working (multi-organ failure, MOF) and there may be a dangerous drop in blood pressure.
Rarely, it may be ordered at intervals to monitor antimicrobial therapy in persons suspected of having sepsis.
What does the test result mean?
Low levels of procalcitonin in a seriously ill person represent a low risk of sepsis and progression to severe sepsis and/or septic shock but do not exclude it. Low concentrations may indicate a localized infection that has not yet become systemic or a systemic infection that is less than six hours old. It may also indicate that the person's symptoms are likely due to another cause, such as transplant rejection, a viral infection, or trauma – post-surgery or otherwise.
High levels indicate a high probability of sepsis, that is, a higher likelihood of a bacterial cause for the symptoms. They also suggest a higher risk of progression to severe sepsis and then to septic shock.
Moderate elevations may be due to a non-infectious condition or due to an early infection and, along with other findings, should be reviewed carefully. Decreasing procalcitonin levels in a person being treated for a severe bacterial infection indicate a response to therapy.
Is there anything else I should know?
The procalcitonin test is not considered a replacement for the performance of other laboratory tests. Rather it is additional information that may allow appropriate treatment to be initiated sooner.
Early detection of systemic bacterial infections, including bacterial pneumonia and bacterial meningitis, is important because they can be life-threatening and can be readily treated. However, the inappropriate use of antibiotics in cases where the illness is not bacterial in origin may cause delays in proper treatment, can encourage the development of antibiotic resistant organisms, and is unnecessarily costly.
The procalcitonin test is being studied in additional populations, expanding beyond critically ill ICU patients. As more data are gathered, its clinical usefulness will be better understood and its intended use(s) more fully defined.
Common Questions
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Related Pages
On This Site
Conditions: Meningitis, Wound and Skin Infections, Sepsis
Elsewhere On The Web
Article Sources
NOTE: This article is based on research that utilizes the sources cited here as well as the collective experience of the Lab Tests Online Editorial Review Board. This article is periodically reviewed by the Editorial Board and may be updated as a result of the review. Any new sources cited will be added to the list and distinguished from the original sources used.
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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 through http://www.medscape.com. 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 through http://www.medscape.com. 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 through http://www.medscape.com. 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 through http://www.medscape.com. 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 through http://www.medscape.com. 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 through http://emedicine.medscape.com. Accessed October 2009.
Lehman, C. (Updated 2009 August). Sepsis in Newborns - Neonatal Sepsis. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/NeonatalSepsis.html?client_ID=LTD through http://www.arupconsult.com. Accessed October 2009.
Lehman, C. et. al. (Updated 2009 August). Pancreatitis, Acute. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/PancreatitisAcute.html?client_ID=LTD# through http://www.arupconsult.com. Accessed October 2009.
Goyal, M. (© 2007). Procalcitonin test could help EPs dx serious bacterial illness faster. Emergency Physicians Monthly [On-line information]. Available online at http://www.epmonthly.com/index.php?option=com_content&task=view&id=263&Itemid=15 through http://www.epmonthly.com. Accessed October 2009.
Carroll, J. et. al. (2007 May 17). Acute Pancreatitis: Diagnosis, Prognosis, and Treatment. American Family Physician [On-line information]. Available online at http://www.aafp.org/afp/20070515/1513.html through http://www.aafp.org. Accessed October 2009.
