Inflammation plays a role in many different diseases, including short-term issues and more chronic inflammatory disorders. Because of this, scientists have worked hard to find “biomarkers” of inflammation.
Through a blood test or other type of test, clinicians can get information about different aspects of inflammation in the body. These tests measure what are called inflammatory biomarkers.
What Are Biomarkers?
A biomarker, also called a biological marker, refers to an objective measurement of something happening inside a person’s body. Such biomarkers provide a lot of important information to clinicians, who use them to help diagnose and properly treat medical conditions. Clinicians use them in assessing almost every patient.
Biomarkers are a broad category. For example, a person’s blood pressure is a type of biomarker. Imaging tests like X-rays are another subcategory of biomarkers.
Other biomarkers might analyze a component of a person’s blood, urine, cerebrospinal fluid, saliva, or stool. Most often, people mean information from blood tests when they talk about biomarkers.
Similarly, there is variability in what exactly biomarkers are testing. Some might be testing for the amounts of certain proteins, while others may analyze the number of a specific type of cell.
What Are Inflammatory Biomarkers?
A biomarker that gives information about inflammation might be called an “inflammatory biomarker.” Sometimes this term is used to describe markers that give additional information about a person’s immune system, even if they aren’t directly involved in inflammation.
Measuring the Inflammatory Response
Inflammation is a complex process in which your body responds to some sort of perceived injury, infection, or toxin. But sometimes the responses get out of hand and cause additional problems.
During inflammation, some of the connections joining your cells can become “leaky.” Because of this, more fluid than normal can fill an area. If you twist your ankle, for example, the area might become red, swollen, warm, and painful.
A lot of other things also happen that are harder to see. Some types of immune cells may become activated. This helps fight an infection, if present, but it also may make it more likely that they will injure nearby cells.
Some cells begin releasing certain cytokines. These are special signaling molecules made by your immune system. These signals can activate even more cells of the immune system, releasing even more cytokines. Some cells may also release certain proteins that activate other parts of the immune system.
Sometimes inflammation goes away on its own. This is called acute inflammation. For example, this might happen to a person with a twisted ankle. The immune system eventually turns off the inflammatory signal, and the area returns to normal.
Other times, the immune system can go into a state of more chronic, long-term inflammation. This can happen in people with autoimmune diseases like rheumatoid arthritis, lupus, inflammatory bowel disease, and many others. More cytokines and more specific immune cells might be present in an area than normal.
Depending on where in the body this is happening, it can cause specific symptoms. For example, someone with rheumatoid arthritis has excess inflammation in their joints. Researchers are still learning about the complex reasons people develop chronic inflammation.
Inflammation is a complex series of actions and reactions in your body. So, it makes sense that there isn’t one single test that measures it. Different inflammatory biomarkers give slightly different information about what is going on.
Inflammatory Biomarker Examples
Some of the more commonly used inflammatory markers used include the following:
- Blood counts (e.g., white blood cell count, red blood cell count, hemoglobin count)
- C-reactive protein (CRP)
- Erythrocyte sedimentation rate (ESR)
Other inflammatory markers are sometimes assessed in specific circumstances.
A standard medical test is the complete blood count (CBC), which gives information about the number of different cells in your blood. A CBC measures:
- Red blood cells (RBCs): These contain hemoglobin, which are the cells that carry oxygen throughout the body. RBCs also remove carbon dioxide from the body by moving it to the lungs so you can exhale it.
- White blood cells (WBCs): These fight infection and other diseases. Types of white blood cells include monocytes, granulocytes (eosinophils, neutrophils, basophils), and lymphocytes (T-cells, B-cells).
- Hemoglobin: These are the oxygen-carrying protein molecules in red blood cells.
- Hematocrit: These measure the proportion of red blood cells to plasma in your blood.
- Platelets (thrombocytes): These help with blood clotting and can stop or prevent bleeding.
Changes in the components of your blood can contribute to inflammation. For example, elevated WBC and platelet counts with low hemoglobin is a surrogate for inflammation.
CBC gives broad information relevant to a lot of different diseases which involve inflammation. Some of these are:
- Autoimmune conditions like vasculitis or inflammatory bowel disease
The CA 15-3 Blood Test for Breast Cancer
CRP (C-Reactive Protein)
CRP is an acute phase reactant, meaning the protein is released by the liver in response to inflammation. It may be elevated in many different inflammatory conditions, including:
- Bacterial or viral infections such as pneumonia, causing acute inflammation
- Many autoimmune diseases like lupus or rheumatoid arthritis, causing chronic inflammation
- Cardiovascular disease
ESR (Erythrocyte Sedimentation Rate)
ESR (“sed rate”) is another commonly used measure of inflammation. Technically, it measures changes to red blood cells (erythrocytes) which can happen due to inflammation.It may be elevated in many different inflammatory medication conditions, including most of the same ones as CRP.
Procalcitonin is another acute phase reactant produced by the liver in response to inflammatory signals. It may be elevated in a number of different inflammatory conditions. However, it is most commonly used to evaluate sepsis, in which the body produces overwhelming inflammation in response to infection.
Calprotectin is a substance found in specific white blood cells (called neutrophils) that are very active in inflammation. The amount of calprotectin in one’s stool can be used to distinguish inflammatory bowel disease from a non-inflammatory cause of one’s symptoms (like irritable bowel syndrome).
Ferritin is a protein in blood that contains iron. A ferritin test, which shows the amount of ferritin in the blood, can determine how much iron one’s body stores. A low blood ferritin level can indicate iron deficiency, whereas a high blood ferritin could indicate rheumatoid arthritis, liver disease, hyperthyroidism, or other inflammatory conditions.
Fibrinogen is a protein produced by the liver. It is the primary protein that helps blood clots to form, assisting with wound healing.
Fibrinogen can be a biomarker for tumors; they are found in above average amounts in the blood and urine of those with cancer. Checking fibrinogen levels can help determine if cancer treatment is working or if the cancer has worsened.
When Doctors Use Biomarkers for Inflammation
Sometimes doctors use these markers as part of the initial diagnostic process. Abnormalities may mean that your condition is likely to be partly caused by inflammation.
These tests can also be used to monitor for the level of a person’s disease activity, like for lupus. This might impact the kind of treatment your doctor suggests.
Sometimes, these biomarkers might be used to give an idea about your disease prognosis. For example, if you have cancer, you might have an increased risk of dying from it if your inflammatory markers are high.
As of now, clinicians don’t generally use inflammatory biomarkers for health screening. But this might change in the future.
Often, more than one marker of inflammation is used at the same time. This can give a more accurate view about whether inflammation is really present.
Inflammatory Biomarker Limitations
One important limitation is that these tests are considered nonspecific. That means that they can’t be used on their own to diagnose disease.
That makes sense, because inflammation is a part of so many different diseases. In other words, knowing that your body has inflammation doesn’t tell you why that inflammation is happening.
Sometimes you might even have inflammation not from an active disease but from something like smoking, pregnancy, aging, or unrelated medical problems. Additionally, these tests often aren’t good indicators about whether a person has chronic inflammation or only temporary inflammation.
It’s important to note that this is a rapidly changing area in medicine. Right now, there are relatively few markers of inflammation that clinicians regularly use.
But researchers are discovering a lot of new information about how we might use inflammatory research markers in the future, potentially in many different diseases. For example, we might eventually use some of these markers to estimate a person’s risk for cancer.
Inflammatory biomarkers are also very helpful when researchers evaluate new potential treatment options.
Your doctor may have you get certain tests for inflammatory biomarkers as part of your diagnosis and ongoing treatment.
For example, if you have painful joints, tests for inflammation can show that you are more likely to have an inflammatory condition like rheumatoid arthritis instead of another medical condition that might cause these issues, like osteoarthritis.
Understanding Result Ranges
When you get your test results back, they’ll usually be put in terms of their normal range. Typically, if your result comes back higher than that normal range, it’s a sign that inflammation might be part of your problem.
If your results come back in the normal range, it’s more likely that you have a problem that doesn’t cause a lot of inflammation.
However, not every inflammatory biomarker is like this. For some, having a lower than normal number might mean that inflammation was involved. And sometimes it makes a difference if your value is a little or a lot out of the normal range.
It’s important to note that such tests aren’t necessary for diagnosing every kind of inflammation, and they don’t always give great information about the level of your disease activity. Your own experience of your symptoms often gives information that is helpful as well.
Seeing the Big Picture
Remember that these results must be used in the context of your complete medical picture. Ask your doctor if you have questions about the interpretation of your specific test results.
What You Can Do
Fortunately, there is often a lot you can do to reduce the inflammation in your body and so reduce your symptoms.
Some of the following may help you reduce your inflammation:
- Eating fewer processed foods and more fruits and vegetables
- Not smoking
- Keeping a healthy weight
- Regularly exercising
With the Help of Your Doctor
Your doctor can help provide resources for all of these (e.g., referral to a nutritionist, medication to help you quit smoking).
Additionally, your doctor can prescribe therapies that can help treat the underlying cause and reduce inflammation. For people who have chronic inflammation, many of the treatment options ultimately work by reducing this inflammation in slightly different ways.
What to Do When Your CRP Is Too High
A Word From Verywell
Inflammation is an incredibly complex process that can be assessed by many different biomarkers. Researchers are still learning about the best ways to use inflammatory biomarkers to diagnose and monitor disease.
The main thing to remember, though, is that you have some control over how to manage your chronic inflammation. By making good health choices and working with your doctor to get the right therapy, you can decrease your symptoms and get your inflammatory biomarkers closer to the normal range.
Frequently Asked Questions
How do doctors use biomarkers to diagnose inflammatory disorders?
By testing for inflammatory biomarkers, a clinician gets clues about the possible causes of your symptoms. If your inflammatory biomarkers are abnormal, it’s a clue that you might have an inflammatory disorder, one in which inflammation is a big cause of the problem.
What helps with chronic inflammation?
You may be able to reduce your chronic inflammation by changing your diet, quitting smoking, exercising more, and taking your medications as prescribed. Doing so can interrupt the inflammatory process, and your inflammatory biomarkers would be more likely to come into the normal range.
What are examples of inflammatory biomarkers?
Some of the most commonly used inflammatory markers are CRP, ESR, procalcitonin, and white blood counts (assessed via a complete blood count). Many others are used in specific circumstances or in research.
How accurate are inflammatory biomarkers?
Inflammatory biomarkers can often give good information about whether inflammation is present, especially when used together. However, their meaning must be interpreted in the context of your medical history, exam, and other tests.