CRP Test: Normal Range, Causes of High and Low CRP

C-reactive protein is a blood test that measures the level of a substance called C-reactive protein (CRP). The liver produces this protein in case there is any inflammatory process in the body. May rise in a few hours after inflammation and may drop during the time after inflammation has decreased. Doctors use it to help assess inflammation in people with symptoms such as fever, pain, or swelling. It might also serve as a way of monitoring someone's response to treatment of some infections or inflammatory diseases. CRP is a general marker of inflammation and cannot show the exact cause, for example, whether an infection is bacterial or viral, although very high levels are more often seen in bacterial infections. The test's results are evaluated in conjunction with other tests, physical examination, symptoms, and history to interpret the results.

What Is the Normal CRP Range?

CRP levels are measured in mg/L. For a standard CRP, the normal level would be below 5mg/L. However, the reference range for CRP may differ between laboratories. Generally:

• Less than 5mg/L – This is considered to be within normal limits.
• Above 5mg/L – This may indicate inflammation or infection.
• High levels may indicate serious infections, serious injuries, or active inflammatory conditions.

The values provided are general guidelines and should not be used to diagnose. Interpretation of CRP levels depends on a person's symptoms, medical history, and the reference range of the laboratory.

What Causes High CRP Levels?

Generally, high CRP levels indicate that there is some form of inflammation occurring within the body. There are several reasons why CRP levels may increase:

• Infections – Both bacterial and viral infections can cause an increase in CRP. This is due to the immune system fighting off harmful microorganisms. Serious infections can cause a significant increase.
• Inflammatory conditions – Conditions such as rheumatoid arthritis, lupus, and inflammatory bowel disease can cause ongoing inflammation and therefore an increase in CRP.
• Tissue damage – Injuries, burns, surgery and other tissue damage can cause inflammation.
• Long-term health conditions – Obesity, smoking and some metabolic conditions may cause an increase in inflammation.
• Other medical conditions – Some cancers and cardiovascular-related inflammation may be associated with increased CRP levels. However, CRP alone cannot be used to diagnose these conditions.

What Causes Low CRP Levels?

Low CRP is generally associated with low levels of demonstrable inflammation in the body. A normal result is generally reassuring, especially if a person has no evidence or symptoms of an inflammatory condition. A low or undetectable CRP is usually normal and not a health concern. They can be observed in healthy people or in persons who have decreased inflammation following treatment. 

A decline may indicate that the inflammatory process is returning to a normal level if the person had a high CRP level before. A normal or low CRP does not completely rule out infection or inflammation, however. There are conditions that may not show a significant increase, particularly in the early hours of an illness.

How Is a CRP Test Performed?

The CRP test is an easy blood test. A small amount of blood (typically from the arm vein) is drawn by a healthcare professional. This is then taken to a lab to determine the level of C-reactive protein. Typically, a normal CRP test should not be accompanied by a period of fasting. The doctor and/or laboratory may make special arrangements if other tests are also being done. The test is used to see whether inflammation is present and to follow it over time. It may be repeated to help determine if the inflammatory condition is going away or getting worse.

CRP Testing at Molecular Diagnostics and Therapy

Doctors can use a better understanding of the level of CRP to determine certain health issues as well as inflammation. Molecular Diagnostics and Therapy is a diagnostic centre that is accredited by NABL and NABH and offers different diagnostic services such as blood investigations. If you or your child develop fever, persistent body pain, or swelling, seek medical advice. Your doctor might also order a CRP test if he or she feels it is necessary, and will rely on the results of the test along with other relevant clinical symptoms to determine your diagnosis.

Conclusion

CRP is an indicator of inflammation throughout the body and is helpful in blood investigations to monitor and detect inflammation. A high level of CRP can be seen in the event of infection, injury, or inflammatory conditions, while in the majority of cases, when the level of CRP is low, little measurable inflammation is present. But the result of a CRP measurement is not enough to determine the cause of a health problem. Properly completed and timely testing, medical evaluation, and a plan for follow-up care may be useful in promoting health management.