How to interpret blood tests for inflammation

We expect elevated markers after illnesses and injuries. At other times, they can indicate chronic inflammation that could increase your risk of serious conditions.

WRITTEN BY

Nicola Bridges

REVIEWED BY

Nick Nwabueze, MD

Updated: 09/05/2025|12 min read

Inflammation is a driver of many chronic conditions, including diabetes, cardiovascular disease, cancer, chronic kidney disease, and more. You may sometimes notice localized inflammation, such as swollen joints or red skin after an injury, and blood markers for inflammation can be high after a recent infection, illness, injury, or surgery. The more worrisome inflammation is chronic and occurs unseen inside the body, where it can damage healthy tissue and DNA.

This is why blood tests for inflammation are increasingly part of medical providers' toolkits for identifying the root causes of symptoms and diagnosing diseases. You may also want to ask for a test if you have chronic symptoms that remain undiagnosed or a family history of autoimmune disease or illnesses associated with chronic inflammation.

This guide explains who should consider a blood test for inflammation, which biomarkers the tests measure, and what the results can tell you.

What is inflammation?

Inflammation is one of your body's most effective natural defense mechanisms, serving as a protective response that helps it heal from infections, injuries, physical traumas, and disease. This process mobilizes your immune system's cells to attack and neutralize unknown invaders---such as germs, viruses, and toxins---while also promoting healing and repair.

Increased blood flow to bring these cells to the affected area causes the signature redness and heat of inflammation, while dilated blood vessels are more permeable, allowing them to deliver healing plasma proteins and white blood cells to the injured or infected area, which leads to swelling. These are forms of visible inflammation.

Inflammation is naturally designed to occur quickly to help wounds heal. This is acute inflammation. Internal organs can also become acutely inflamed from a transient infection or medication side effect, like non-steroidal anti-inflammatory drugs (NSAIDS), causing acute kidney inflammation. All of this is a healthy, normal response that ends once the injury or infection is healed.

The concern is with chronic, internal inflammation. A diet high in processed foods, lack of physical activity, excessive alcohol consumption, prolonged lack of sleep, autoimmune diseases, and unresolved infections can all contribute to internal inflammation of the organs, tissues, or biological systems, such as arteries. When this occurs, your emergency response system gets stuck in the "on" position, but you may not notice symptoms for months or even years.

Blood testing can reveal an abnormal blood panel or out-of-range biomarker levels. Changes in vitals, such as high or low blood pressure or heart rate, can indicate inflammation. Until it's discovered and addressed, the inflammation causes damage inside your body that can eventually contribute to conditions and diseases such as heart disease, stroke, diabetes, arthritis, Alzheimer's disease, and some cancers.

When should you consider a blood test to check for inflammation?

Not everyone needs to test for inflammation, but this blood work can be valuable in several situations:

• When you have unexplained symptoms, such as joint pain, muscle aches, persistent fatigue, or frequent infections (all potential signs of inflammation taking hold in your body).
• If you have a family history of autoimmune diseases, such as rheumatoid arthritis or lupus. The test can help detect these diseases early.
• To help monitor existing conditions, such as diabetes, cardiovascular disease (CVD), or rheumatoid arthritis. Regular testing helps assess how well your treatment plan is working.
• As part of preventive care, especially if you have risk factors for conditions such as CVD. Inflammation tests provide a more complete picture of your cardiovascular health.
• When other blood tests show abnormalities often connected to inflammation, including elevated liver enzymes or anemia.

What conditions are linked to inflammation?

Chronic inflammation contributes to many common health problems and has been called the "cause of all diseases." Understanding the connections to these conditions can help you understand why you may want to get a blood test for inflammation.

• Heart disease and stroke: Inflammation damages blood vessel walls and makes plaques (the buildup of cholesterol, fat, and other substances) on artery walls more likely to rupture, causing heart attacks and strokes.
• Type 2 diabetes: Obesity-induced chronic inflammation triggers the release of cytokines that interfere with insulin signaling, leading to insulin resistance and potential diabetes complications such as retinopathy, diabetic nephropathy, and CVD.
• Arthritis: Rheumatoid arthritis is chronic inflammation caused by the immune system mistakenly attacking joint tissues. As bone cartilage wears down with osteoarthritis (the "wear and tear" type of arthritis), the synovium (the lining of the joint) can become irritated, triggering an inflammatory response.
• Autoimmune diseases: Conditions like lupus, multiple sclerosis, and inflammatory bowel disease occur when your immune system mistakenly attacks healthy tissues, causing chronic inflammation.
• Cancer: Research is confirming that long-term inflammation plays a pivotal role in cancer development and growth. It appears to induce immunosuppression, or a weakened immune system, leading to an environment where tumors grow more easily. Inflammation also promotes angiogenesis, the formation of new blood vessels that tumors need to grow.
• Alzheimer's disease: Studies are now proving that brain inflammation appears to play a role in the development and progression of Alzheimer's and other forms of dementia.
• Depression: Emerging research suggests that inflammation may contribute to depression in some people, which might explain why some people with inflammatory diseases have higher rates of depression.\

What inflammatory markers in blood tests tell you

Different inflammation markers can indicate different causes of inflammation, but one marker alone isn't enough to properly diagnose what's going on. Your provider may need all of these markers combined, as well as your current medical status and lifestyle, and, at times, other tests, to get a more complete picture of your inflammation.

The following are the most reliable and commonly used markers for detecting inflammation that may indicate or contribute to a chronic condition, such as CVD, diabetes, or arthritis. Here's what each measures, what normal ranges are, and what your results might mean.

High-sensitivity C-reactive protein (hsCRP)

High-sensitivity C-reactive protein (hsCRP) is the test most commonly used to assess inflammation. Anytime there's inflammation in the body---whether that's from infection, injury, or an inflammatory disease---the liver increases production of C-reactive protein (CRP). CRP binds to polysaccharides on the surface of pathogens so the immune system can identify and eliminate them, and on the surface of damaged cells so they can be removed.

Currently, the hsCRP test is typically ordered to help assess high risk for heart attacks, monitor autoimmune diseases, or evaluate acute issues. However, some researchers believe it should be used as a routine screening tool for cardiovascular disease, even in those who are asymptomatic, due to its ability to predict the risk of heart attack and stroke.

There's no medical consensus on an optimal hsCRP level, however, lower ranges are considered best for overall health. Many metabolic health specialists suggest aiming for below 0.5 to 1.0 milligrams per liter (mg/L) to reduce the risk of autoimmune and other inflammation-related conditions, as well as CVD.

Illness and injury can elevate CRP for up to about three to seven days, but if you have chronic inflammation, CRP levels remain elevated. So, repeat tests of CRP and other markers of inflammation are needed to diagnose chronic inflammation---your clinician will determine the best time between tests. (Note that CRP and hsCRP tests are not one-to-one interchangeable. For example, standard CRP tests measurer higher levels [typically >10 mg/L] and are used for detecting acute infections or inflammation, whereas hsCRP is a more sensitive assay for detecting low-level chronic inflammation relevant to cardiovascular risk.) Results that may indicate unseen chronic inflammation are generally categorized as follows:

• Low CRP (<1.0 mg/L): This suggests you don't have significant inflammation.
• Moderate CRP (1.0-3.0 mg/L): This might indicate low-level chronic inflammation, which can increase your risk for heart disease and earlier onset of cardiometabolic multimorbidity (CMM), the coexistence of two or more cardiometabolic disease, including CVD, coronary artery disease, hypertension, Type 2 diabetes, or stroke. Even slightly elevated CRP levels can predict future heart problems.
• High CRP (>3.0 mg/L): This suggests active inflammation. Very high levels (above 10 mg/L) often mean you have an infection or active inflammatory disease.

Erythrocyte sedimentation rate (ESR)

The erythrocyte sedimentation rate (ESR) test---also called the "sed rate" test---measures how fast your red blood cells settle to the bottom of a test tube in one hour and is commonly used to check for or monitor increased inflammatory activity.

When you have inflammation, levels of positive acute-phase proteins in the blood---such as CRP, serum amyloid A (SAA), and fibrinogen---rise. These proteins limit viral replication and spread, transport nutrients to the affected area, and promote coagulation of red blood cells, respectively. That may seem like a bad thing, since it increases the risk of blood clots, but when you're injured, coagulation prevents excess blood loss and promotes wound healing. In a test tube, red blood cells that stick together fall faster than normal. 

Normal ESR results vary by age and gender and generally mean no significant inflammation:

• Male <50 years old: ≤15 millimeters per hour (mm/hr)
• Female <50 years old: ≤ 20 mm/hr
• Male >50 years old: ≤20 mm/hr
• Female >50 years old: ≤30 mm/hr

As with CRP, ESR stays acutely elevated after events such as trauma, surgery, or injury. But repeated results higher than the above parameters suggest chronic inflammation somewhere in your body. Though an ESR test can't tell you the location, research confirms levels higher than 100 mm/hr can indicate infection, autoimmune diseases (such as lupus), renal disease, and malignancies/cancers. Lifestyle habits, including alcohol use, smoking, and inactivity, also factor in, causing inflammation and, in turn, higher ESR levels, so be honest when discussing these things with your doctor.

CRP and ESR often, but don't always, increase and decrease together. Many people can have elevated ESR but normal CRP, partly because ESR rises and falls more slowly than CRP. However, this may also indicate cancer or lupus, a chronic autoimmune disease where the immune system attacks healthy tissues. On the other hand, elevated CRP and normal ESR may indicate an infection or tissue damage, such as a heart attack or blood clots. 

Both CRP and ESR may be better at diagnosing different conditions, but using both increases the accuracy of diagnosis.

Fibrinogen

Fibrinogen is a protein synthesized by the liver that helps your blood clot when you're injured, so you don't lose too much blood. It's even administered as a proinflammatory to help with clotting during traumas, surgeries, and transplants. During clotting, fibrinogen is converted into fibrin, a fibrous protein that forms a physical barrier and can trap bacteria, preventing a spreading infection, and provides the foundation for wound healing. 

But in everyday life, high levels of fibrinogen indicate not only inflammation but also risk for blood clots and, as a result, cardiovascular disease, strokes, and thrombosis. (Conversely, low fibrinogen increases bleeding risk and impedes the ability to create clots and heal wounds.)

Fibrinogen test results are generally categorized as follows:

• Normal fibrinogen: 200-400 milligrams per deciliter (mg/dL). Suggests no major inflammation and normal clotting function.
• High fibrinogen: 400+ mg/dL. May indicate inflammation and increased risk for heart disease or stroke.
• Low fibrinogen: <200 mg/dL. Could suggest liver problems or certain genetic conditions.
• Low fibrinogen: <200 mg/dL. Could suggest liver problems or certain genetic conditions.

Generally, people with elevated CRP also have elevated fibrinogen since both are positive acute-phase proteins.

Ferritin

When all of a cell's iron needs have been met, the protein ferritin stores extra iron within the cell so it can be released when needed. Most people think of ferritin as an indicator of iron levels, but your body also increases production during inflammation as part of its defense strategy. Ferritin binds to iron, preventing bacteria from accessing and using it to grow, and it helps regulate immune cell function.

Normal ferritin results vary by gender (note that reference ranges vary substantially between sources):

• Female: <12-150 nanograms per milliliter (ng/mL)
• Male: <12-300 ng/mL

Although it may vary by clinical authorities, generally, a ferritin level below 30 ng/ml may indicate iron deficiency, while high ferritin may indicate inflammation, infection, liver disease, or iron overload (an excessive amount of iron stored in the body). If you have high ferritin, physicians typically do further testing and collect your family history. This can help them determine if the cause is inflammation, excessive dietary or supplementary iron, or genetic hyperferritinemia, an inherited condition with elevated iron levels.

What's next if blood test results show abnormal inflammation?

If your blood tests reveal elevated inflammation markers, this doesn't always indicate a serious problem. Your inflammation markers may be high if you've had a recent infection, illness, injury, or surgery; if you take certain medications (such as hormone replacement therapy or birth control pills); if you're stressed; or if you recently did an intense workout.

So seek medical guidance. Determining where the inflammation is, what's causing it, and what it means for your health requires further investigation, looking not only at these numbers but also additional health markers, family history, and contributing factors, including lifestyle habits. Your provider may perform other tests, such as a physical exam of the bothersome area, more blood tests, or imaging tests like an MRI to look at sites of the inflammation.

With all this information, your physician can assess with you whether elevated inflammation markers indicate a concern and discuss possible next steps, such as medical treatment or lifestyle changes. If you have an existing condition, your current treatment course may need adjusting.

Test your blood inflammation levels

Levels members can test dozens of markers, including a those for inflammation, through Levels Labs, and then use the Levels app to help improve levels by logging meals and setting exercise goals. Click here to learn more about Levels.