I. Introduction

Sepsis is a serious condition that develops in response to a severe infection. Some of the changes that occur during sepsis result in reduced blood flow to the vital organs, which can lead to organ failure. According to an article published in the journal Critical Care Medicine, sepsis affects approximately 1.7 million American adults each year. Meningitis, inflammation of the membranes covering the spinal cord and brain, is an example of an infection that can increase the amount of procalcitonin in the blood. The causes of meningitis include bacteria, viruses, fungi, certain medications, and injuries to the brain and spinal cord. According to the CDC, approximately 1.2 million cases of bacterial meningitis are diagnosed each year.

This guide provides an overview of the procalcitonin test, including why it’s ordered and how it’s done. It also provides detailed information on sepsis and meningitis, two conditions that can cause increased procalcitonin levels.

II. Overview of the Procalcitonin Test

Why should I get tested?

The purpose of the procalcitonin test is to determine if an individual has a higher-than-normal amount of procalcitonin in the blood. In healthy individuals, almost all procalcitonin is made into calcitonin; thus, very little procalcitonin circulates in the bloodstream. A significant increase in procalcitonin can indicate the presence of a severe infection or the development of sepsis, both of which can have life-threatening consequences without prompt treatment. The procalcitonin test is also used to determine how well an individual is responding to antibiotic treatment. Vijayan et al. suggest that the procalcitonin test may be useful for helping healthcare providers determine when to discontinue antibiotic treatment, which can help prevent antibiotic resistance.

When should I get tested?

The procalcitonin test should be performed as soon as an individual displays signs or symptoms of sepsis or a severe infection. In individuals being treated with antibiotics, the procalcitonin test should also be performed at regular intervals to determine if the antibiotic is effective.

What is required for the test?

The procalcitonin test is performed on a blood sample.

What do I need to do to prepare for the test?

No special preparation is required for the procalcitonin test.

III. The Basics of Sepsis and Meningitis

Sepsis

Sepsis develops when the immune system launches an “overwhelming response” to an infection, releasing pro-inflammatory chemicals into the bloodstream and triggering a series of changes that reduce blood pressure, increase heart rate, and cause shortness of breath. Without treatment, these changes can quickly cause the kidneys or other organs to fail, increasing the risk of death. The CDC estimates that 270,000 Americans die from sepsis each year; furthermore, one out of every three people who die in a hospital has sepsis at the time of death.

Sepsis can happen to anyone, but it’s more common in certain populations. For example, very young and very old people are more likely to develop sepsis than young or middle-aged adults. People with weak immune systems and chronic health problems, such as cancer, kidney disease, and diabetes, have a heightened risk of developing sepsis. Sepsis is also more likely to develop in people suffering from trauma or severe burns.

The most common signs and symptoms of sepsis include rapid heart rate, fever, chills, confusion, rapid breathing, skin rashes, and disorientation. Due to the risk for organ failure and death associated with sepsis, individuals diagnosed with this condition are usually admitted to an intensive-care unit for treatment.

Meningitis

Meningitis develops when something causes inflammation of the meninges, which are the membranes that protect the brain and spinal cord. Sometimes inflammation occurs when an infectious organism, such as a virus or bacterium, comes into contact with the meninges. Meningitis can also occur due to drug allergies, chemical exposure, or tumors of the brain or spinal cord. Viral meningitis is the most common form of the condition, and it can be caused by a variety of viruses, including enteroviruses, HIV, mumps, herpes, and West Nile virus. Enteroviruses are the viruses that live in the digestive tract and cause diseases, such as hepatitis A. Bacterial meningitis is less common than viral meningitis, but it’s also more severe.

Several factors increase an individual’s risk of contracting meningitis. Like sepsis, meningitis is more common in people who are very young (infants and toddlers) or very old. Geography also affects an individual’s risk of contracting meningitis, as the condition is more prevalent in some countries than others. For example, sub-Saharan Africa has a region known as the “meningitis belt” in which there have been up to 1,000 cases of meningitis per 100,000 people during the dry season. In contrast, the United States and other developed nations typically have just 0.12 to three cases of meningitis per 100,000 people per year, according to the CDC.

Attending mass gatherings and sharing living quarters with many people also tend to increase the risk for contracting meningitis. In the United States, many colleges and universities require students living in campus housing to receive the meningitis vaccine due to the risk that a meningitis outbreak could occur in a crowded dormitory. Soldiers living in military barracks also have a slightly increased risk of contracting meningitis, when compared to the general population.

The signs and symptoms of meningitis depend on the underlying cause. Viral meningitis is less severe than bacterial meningitis, so it may cause fatigue, diarrhea, headache, slight fever, and sensitivity to light. Bacterial meningitis causes symptoms, such as nausea, vomiting, confusion and other changes in mental status, fever, chills, stiff neck, and severe headache. Meningitis may also cause rapid breathing, agitation, lack of alertness, and unusual arching of the back and neck. In infants and young children, bulging soft spots and poor feeding are potential signs of meningitis.

In cases of suspected meningitis, confirmation of the diagnosis is made by taking a sample of the individual’s cerebrospinal fluid and analyzing it in a laboratory. In individuals with meningitis, the cerebrospinal fluid may have an unusual color, contain an abnormal number of white blood cells, have a lower-than-normal amount of glucose, or have an increased amount of protein.

IV. How a Procalcitonin Test Works

The procalcitonin test requires a blood sample, which is usually collected by a phlebotomist, a medical professional who has been trained to collect laboratory specimens. Many individuals who need the procalcitonin test have already been admitted to the hospital; if this is the case, a phlebotomist will come to the individual’s bedside to draw blood. If the test is ordered on an outpatient basis, the individual must visit a draw site, which may be located in a hospital, medical clinic, or outpatient laboratory.

Blood samples are collected via a procedure known as venipuncture, which means “to puncture a vein.” During this procedure, a phlebotomist inserts a needle into one of the individual’s veins and allows blood to drain into a glass or plastic collection tube containing an anticoagulant, which is a substance used to prevent the blood from clotting. Once the blood sample has been collected, the phlebotomist mixes the blood with the anticoagulant by inverting the tube.

Laboratory personnel measure the amount of procalcitonin in the individual’s blood sample by using chemiluminescent particle assay or chemiluminescent immunoassay. These methodologies use antibodies labeled with enzymes to detect procalcitonin in the blood.

V. Treatment for Sepsis and Meningitis

Sepsis

Sepsis can be life-threatening, making immediate treatment essential. Even with appropriate treatment, approximately 20% of individuals who develop sepsis die from it, according to the National Institutes of Health. One of the main goals of sepsis treatment is to prevent organ failure. This is accomplished by administering intravenous fluids, which increases blood pressure and helps maintain normal blood flow to the vital organs. If administering fluids doesn’t work, medications known as vasopressors may be used to ensure the vital organs receive an adequate supply of blood. Vasopressors cause the blood vessels to constrict, increasing blood pressure.

In an article prepared for the American Academy of Family Physicians, Dr. Robert L. Gauer states that an individual with sepsis should start antibiotic therapy within one hour of diagnosis. The antibiotic used depends on the underlying cause of the sepsis. Vancomycin is often given to individuals with community-acquired pneumonia, meningitis, and infections of the skin and soft tissues, while piperacillin may be administered for sepsis arising from serious urinary tract infections, pelvic infections, or infections within the abdominal cavity.

Several other treatment methods may be used to prevent complications in people with sepsis. In some individuals, a blood thinner called heparin is used to prevent blood clots from forming. For people who don’t respond to intravenous fluids or vasopressors, corticosteroids may be used to increase blood pressure and prevent organ failure. High blood sugar can make sepsis worse, so individuals with diabetes may have to take insulin to keep their glucose levels under control while they’re in the hospital. In some cases, blood products are administered to improve outcomes in people with sepsis. For example, packed red cells can be used to improve an individual’s oxygen saturation.

Meningitis

The American Academy of Family Physicians recommends starting antibiotic therapy immediately in any individual with suspected meningitis, even if CSF analysis is still in progress. If the individual has bacterial meningitis, a delay in starting antibiotics can be deadly. Should the CSF analysis indicate that the individual has meningitis caused by a virus, fungus, or parasite, the antibiotics can be discontinued. Individuals with meningitis caused by Haemophilus influenzae or Neisseria meningitidis usually take antibiotics for seven days; it may take 21 days or more to eradicate Listeria monocytogenes.

In individuals with bacterial meningitis, corticosteroids may also be used to reduce inflammation, which can prevent complications such as hearing loss. Dexamethasone is typically given to infants and children with H. influenzae type B infections, adults with meningitis caused by S. pneumoniae, and individuals with infections caused by Mycobacterium tuberculosis who do not have HIV. Corticosteroids may also be helpful for children with pneumococcal meningitis. Viral meningitis usually clears up on its own, but antiviral medications may be used to treat people who have meningitis caused by influenza or herpes. When meningitis is caused by a fungus, it’s treated with intravenous antifungal medications.

VI. FAQs

What is a normal procalcitonin level?

In adults, children, and infants over 48 hours old, a normal procalcitonin level is less than 0.1 nanograms per milliliter (ng/mL). Procalcitonin levels are higher in newborns, ranging from less than or equal to 2 ng/mL to less than or equal to 21 ng/mL, depending on how many hours it’s been since birth.

What does an elevated procalcitonin level mean?

An elevated procalcitonin level indicates that something is causing inflammation in the body. Mildly elevated procalcitonin levels, ranging from 0.10 to .49 ng/mL, indicate a minor inflammatory response, which can occur in cases of localized infection. An individual with a procalcitonin level ranging from 0.5 to 1.99 ng/mL has a moderate risk of developing a severe systemic infection. A procalcitonin level between 2.0 and 9.99 ng/mL usually indicates sepsis, but it may also be due to recent trauma. An individual with a procalcitonin level greater than 10 ng/mL has a high likelihood of having sepsis or developing severe septic shock.

Are there any risks to the procalcitonin test?

The procalcitonin test has the same risks as any other blood test. Some people start sweating or feel lightheaded while having their blood drawn. Puncturing a vein also carries a small risk of infection, but the risk is reduced by cleansing the skin with an alcohol wipe before inserting the needle.

If my procalcitonin level is high, will I need additional tests?

Yes. Although procalcitonin is a useful marker for diagnosing and managing sepsis, it can’t determine the cause of an infection. An individual with a high procalcitonin level may need blood cultures or other blood tests to determine if the infection is bacterial, viral, parasitic, or fungal. If an individual may have meningitis, a lumbar puncture will be needed to collect a sample of CSF for analysis. In cases of suspected meningitis, it may also be necessary for the individual to provide a urine sample or have fluid samples collected from the throat or nose.

Can anything other than sepsis or a severe infection cause abnormal procalcitonin levels?

Yes. Procalcitonin levels may be elevated in individuals with medullary thyroid cancer, a rare type of cancer that starts in the C cells of the thyroid gland. These cells secrete calcitonin, which is made from procalcitonin. Increased procalcitonin levels are also seen in people with small cell lung cancer, reduced blood flow to the organs, invasive fungal infections, and recent trauma.

VII. Additional Resources

For more information on sepsis and meningitis, along with the tests used to diagnose and manage these conditions, view these additional resources.

NameWebSummary
MedlinePlusmedlineplus.govMedlinePlus provides an overview of the procalcitonin blood test.
Centers for Disease Control and Preventionwww.cdc.govLearn more about sepsis.
Meningitis Research Foundationwww.meningitis.orgThe MRF offers educational materials on meningitis and a blood infection called septicemia.
Johns Hopkins Medicinewww.hopkinsmedicine.orgFind out more about bacterial meningitis, a life-threatening infection that can cause brain injuries and other severe complications.
American Association for Clinical Chemistrywww.aacc.orgDr. Sutirtha Chakraborty discusses the use of the procalcitonin test in diagnosing sepsis.

VIII. Sources Used in This Article