Procalcitonin

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.

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.

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.

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.