Procalcitonin Test

Procalcitonin or PCT acts as a precursor to the hormone calcitonin. This means that your body forms procalcitonin from which calcitonin is created. In recent times, procalcitonin has become an excellent biomarker (a biological molecule that indicates a normal or abnormal condition). Procalcitonin acts as an early biomarker for the detection of systemic bacterial infections.

Experts discovered that patients positive for bacterial infections or sepsis also had high serum levels of procalcitonin. However, PCT levels were not elevated in patients with viral infections. Patients administered appropriate antibiotic medications according to their diagnosed diseases saw a fall in their PCT levels. This further indicated that procalcitonin was a biomarker that could specifically differentiate between the presence of bacterial and non-bacterial infections.

Currently, PCT assays have been developed that are 79% accurate in being able to acutely determine if a bacterial species is the cause behind a person's inflammation or disease. Usually, the biological processes of our body ensure that there are very low levels of procalcitonin present in the blood. But the body sees an increase in the production of PCT by 100 to 1000 fold during bacterial infections.

A procalcitonin test measures the level of the hormone PCT in your blood. High levels of procalcitonin indicate the presence of severe bacterial infections such as sepsis. Sepsis occurs when the body responds severely to an infection. Infection from one part of the body, such as your urinary tract or skin, ends up spreading into the bloodstream resulting in sepsis.

This causes the body's immune system to react strongly and results in rapid heartbeat, shortness of breath etc. Untreated sepsis can lead to organ failure or death. The procalcitonin test results will help your doctor determine if you have sepsis or other severe bacterial infections. This helps in timely treatment and avoiding life-threatening complications.

Sepsis, Bacterial infections, Kidney infections, the severity of infection

The procalcitonin test measures the level of PCT hormone in the blood.

An infection or inflammation is suspected when the doctor orders a procalcitonin test. The symptoms under which the test is prescribed includes:

• Fever
• Chills
• Sweating
• Confusion
• Extreme pain
• Feeling tired or fatigued
• Cough
• Pain in chest
• Swollen lymph nodes
• Headache
• Clammy or sweaty
• Flushed skin
• Less frequent urination
• Swelling or soreness
• GI symptoms such as nausea, vomiting, diarrhoea.

Some conditions for which a prolactin test can be prescribed are:

• Severe bacterial infections
• Sepsis
• Pneumonia
• Meningitis
• A child has symptoms of urinary tract infections
• Monitoring the effectiveness of antibiotics therapy

Your doctor may suspect sepsis and order a procalcitonin test in case you have these symptoms:

• Rapid heartbeat
• Rapid breathing
• Shortness of breath

The test is usually performed in the hospital or when a patient comes to the ICU. You might be recommended to take the procalcitonin test at regular intervals if a doctor wants to monitor antibiotic treatment. This also helps a doctor decide if the treatment can be discontinued. The prolactin test is also prescribed if someone has tissue damage due to trauma, surgery or burns.

Doctors prescribe a procalcitonin test when a patient comes in with symptoms of infections such as fever, chills, confusion, dizziness, fatigue, rapid heartbeat, etc. The procalcitonin test results can help your doctor diagnose the severity of the bacterial infection behind your condition. The PCT test is also used as a diagnostic tool to evaluate the effectiveness of a treatment plan.

If you are diagnosed with a bacterial infection, your doctor will prescribe you related antibiotics that can help manage your condition. After that, your doctor may recommend a procalcitonin test every two to three days to evaluate the effectiveness of the treatment. However, decisions for changing antibiotic dosages should not be solely based on procalcitonin levels.

Before  the Test

Typically, no special preparations are required for a procalcitonin test. However, if you are undergoing this test alongside another one, your healthcare provider may advise you on specific dietary restrictions. It's always best to consult with your doctor before the test for personalised guidance.

During the Test

The blood sample will be drawn from a vein in your arm. Here's what you can anticipate during the test:

• The area where the needle will be inserted will be cleaned with an antiseptic.
• A tourniquet band will be placed around your arm to make the veins easier to locate.
• A quick pinch may be felt as the needle is inserted into the vein to draw the blood. This process typically takes a few seconds.
• The collected blood will be stored in a vial or a small test tube labelled with your test details.

After the Test

Once the blood is collected:

• An adhesive plaster will be placed over the puncture site to prevent bleeding.
• Mild bruising may occur, feeling dizzy is less common. You might be advised to rest for a few minutes.
• Consult  with your healthcare provider if you experience bleeding, pain, or rashes at the puncture site.

The procalcitonin test measures one parameter: the level of the PCT hormone in the blood. The level of procalcitonin tends to rise significantly in systemic bacterial infections and sepsis. Sepsis is the body's immune severe and sometimes life-threatening response towards bacterial infection. Usually, the immune system targets the bacteria and limits its response towards the infected area.

Sometimes, an infection may begin in another area and spread to the blood (bacteremia). In sepsis, the body produces a generalised inflammatory response towards the disease that causes various symptoms. If not treated successfully, sepsis can result in life-threatening conditions.

The results of the procalcitonin test do not evaluate the functioning of any organ. It only indicates the presence and severity of a bacterial infection. 

The normal values and reference ranges of the test may vary from lab to lab. Please refer to the ranges mentioned in the report and consult a doctor to understand the interpretation of lab reports.

Procalcitonin test results are interpreted by the doctor supported with findings from clinical evaluations and other laboratory tests. If you are seriously sick and have low prolactin levels, that indicates a low risk of developing sepsis.

It also means a reduced risk of the illness progressing to severe sepsis or septic shock is minor. However, the doctor can order the test again after 2-3 days to monitor the levels.

High procalcitonin levels indicate an increased risk of sepsis and higher chances of the infection progressing to severe sepsis or septic shock. High levels of PCT is also seen in people with serious bacterial infections such as meningitis.

If your procalcitonin test results reveal moderate levels, it can be due to a non-infectious condition or an early infection. This condition should be reviewed carefully and is also seen in kids with kidney infections.

If the procalcitonin levels have decreased during treatment for infection indicates that the treatment is working. Worsening or continuously high levels of prolactin suggests the need for close monitoring and continued therapy.