I. What is CRP Testing?

An elevated C-reactive protein level indicates that something is causing inflammation in your body.

Why should you get tested?

You should have this test if you have any symptoms of an infection. It’s helpful to get this test if your doctor believes you’re at risk for developing heart disease or having a heart attack.

Who should get tested?

Anyone with symptoms of a serious infection or inflammatory disorder and people who are concerned about their risk for heart disease should have the CRP test.

When to get tested

Get tested if you have severe symptoms or if your symptoms persist for more than a week.

II. How to Prepare for CRP Testing

No special preparation is required for the CRP test. If you have other tests scheduled, ask your doctor how to prepare. Some tests, such as the basic metabolic panel, require an overnight fast. If fasting is required, you’ll need to refrain from eating or drinking anything for eight to 12 hours. Timing can affect the accuracy of some tests, so if you’re having a stress panel or another hormone-related test, you may need to have your blood drawn at a specific time of day.

III. How CRP Testing Works

To have the CRP test, you’ll need to give a blood sample. If you decide to have blood drawn at a doctor’s office or an outpatient laboratory, be prepared to show ID and provide your insurance information. A medical technician will select a site for the draw by examining your hands and arms. Once an appropriate site has been identified, you can expect the technician to tie a tourniquet around your upper arm, cleanse your skin with an alcohol pad, and insert a needle into the vein. The blood sample is collected in a tube and sent to a laboratory to be analyzed.

Several companies now offer home CRP testing. The exact collection method depends on the test provider, but home testing usually requires a finger prick. After you collect the sample, you’ll send it back to the lab and wait to receive the results.

IV. Understanding CRP Testing Results

If you have blood drawn at your doctor’s office or in a standalone laboratory, you should receive your CRP test results within a few days. Your doctor needs to review the results of other lab tests before determining whether your CRP level is cause for concern, so it may take a few extra days for your results to be reviewed and communicated to you. Normal results for a CRP test vary by laboratory, but a reading of less than 10 milligrams per liter is usually considered normal. If you have an elevated CRP level, your doctor may order additional tests or develop a treatment plan based on your current symptoms.

The turnaround time for home testing depends on the test provider. For example, EverlyWell typically reports results no more than five business days after the laboratory starts processing the sample.

V. FAQs

What is a normal CRP level?

Laboratories use different reference ranges for the CRP test, so what is normal according to one laboratory may not be normal according to another laboratory; however, healthy individuals normally have low levels of CRP in their blood.

If my CRP is high, does that mean I have some kind of disease or disorder?

Not necessarily. A high CRP level can be caused by many conditions and situations, including connective tissue disease, cancer, rheumatoid arthritis, heart attack, infection, lupus, and other diseases. Elevated CRP levels can also be caused by tobacco use, lack of physical activity, and obesity, so just because an individual has a high CRP does not mean there is an underlying disease or disorder.

My doctor wants me to have the hs-CRP test. Is this the same as the CRP test?

The CRP test and the hs-CRP test are similar, but they are not exactly the same. While the CRP test is used in the diagnosis and management of inflammatory conditions, the hs-CRP test detects much smaller quantities of CRP in the blood, making it useful for determining whether an individual has an increased risk of heart disease. Another difference between the two tests is that it costs less to perform the standard CRP test than it does to perform the hs-CRP test.

Can any of my medications affect my CRP level?

Yes. Some medications are known to reduce CRP levels, which can have an effect on the results of the CRP test. These medications include aspirin, antioxidants, ACE inhibitors used to control high blood pressure, and drugs used to reduce cholesterol levels. Individuals taking any of these medications should inform their doctor before having the CRP test.

If my CRP level is elevated, will I need more tests?

Probably. Although the CRP test is useful for determining if an individual has a high level of inflammation, it does not identify the exact cause of the inflammation. Therefore, more tests may be needed to determine the cause of an individual’s symptoms. If a health care provider suspects that an individual has an autoimmune disease, the ANA test can help determine if the individual has antinuclear antibodies in their blood. Antinuclear antibodies attack healthy cells, damaging the tissues and causing the symptoms of autoimmune disorders like lupus, rheumatoid arthritis, scleroderma, and Sjogren’s syndrome.

The anti-dsDNA test is also used in the diagnosis of autoimmune disorders. This test determines if an individual has antibodies to double-stranded DNA in their blood. These antibodies damage a person’s DNA, causing symptoms such as fatigue, joint pain, muscle aches, and fevers of unknown origin. If a medical professional suspects that cancer is the cause of an individual’s symptoms, the complete blood count can be used to determine if the person has a normal number of white blood cells, red blood cells, hemoglobin, and platelets.

Do some people have higher levels of CRP than others?

Yes. CRP levels tend to be higher in older people, African Americans, and women.

Are there any risks to having the CRP test?

Because the CRP test involves providing a blood sample, there is a slight risk of having a bacterial infection develop after the blood draw. In some individuals, soreness and bruising occur at the venipuncture site.

VI. Learn From Our CRP Testing Sources

Want to know more about CRP testing? Check out the sources used to compile this guide.