Measuring Inflammation: The Differences Between Erythrocyte Sedimentation Rate (ESR) and C-Reactive Protein (CRP)

Inflammation often gets a bad rap. But it's a necessary process for your body to protect itself. During inflammation, your body uses its own immune system to heal injuries. Short-term (acute) inflammation is healthy and essential. But when inflammation malfunctions and goes on longer than necessary, it becomes chronic inflammation. This can be harmful to your health.

Erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) are two markers that can be measured from a blood sample. They represent the level of inflammation in your body at the time of the test.

If you've had lab work done and had high levels of ESR or CRP, you may be worried about what this means for you. Here's the short answer: It really depends on how high the levels are and what else is going on with your overall health.

What are ESR and CRP?

ESR (also known as "sed rate" or Westergren sedimentation rate) measures how quickly red blood cells (erythrocytes) drop (or create sediment) in a test tube. It's measured in millimeters per hour (mm/hr). ESR is an indirect marker of the inflammation levels in your body because when inflammation is high, it takes longer for the red blood cells to drop.

CRP is a protein that your liver creates in response to inflammation. The levels in your blood increase when your body is inflamed.

What is the relation between ESR and CRP?

The most important thing to understand about the relation between ESR and CRP is that they both increase with active inflammation. But there are some differences in how quickly they increase. CRP rises faster and falls more quickly (within about 3 days) after inflammation is resolved. ESR takes longer to rise and stays higher for longer after the inflammation is resolved.

What are the normal ranges for CRP and ESR?

This can vary based on the laboratory that is running your blood tests. An individual's "normal" level of CRP and ESR can depend on things like age, sex, and active chronic diseases:

• A normal CRP level is less than 1.0 mg/dL (or 10 mg/L, depending on the units the lab is using).

• A normal ESR is usually less than 20 mm/hr.

The normal ESR range can also be broken down further by age and sex.

What diseases cause high ESR/CRP?

There are many diseases, conditions, and even injuries that cause inflammation, which can raise ESR/CRP. A high ESR/CRP doesn't point to one specific disease or group of diseases. They're helpful, but pretty non-specific tests.

Here are some of the most common diseases and situations associated with high ESR/CRP levels.

Autoimmune disease

In autoimmune diseases like rheumatoid arthritis and lupus, the immune system attacks its own body. This chronic inflammation means that ESR/CRP levels go up - and stay up. Monitoring ESR/CRP levels in autoimmune disease can help you and your healthcare team know how well your treatment is working.

Infection

When your body is infected by a bacteria or a virus, it ramps up its inflammatory response to fight the invader. This causes a raised ESR/CRP, which then goes back down once the infection resolves.

Cancer

In cancer, the fast, uncontrolled growth and turnover of cells causes inflammation levels to rise, leading to high ESR/CRP.

Lack of blood flow

Cells become injured when they don't get the nutrients they need to function. In a heart attack or stroke, cells don't get the blood or oxygen they need. This can cause increased inflammation - and raised ESR/CRP levels.

Injury or surgery

After a physical injury or surgery, your body needs to repair what's broken. Your body does this by increasing inflammation to fix the injured area.

Pregnancy

Both inflammatory markers usually increase during pregnancy, with ESR rising more than CRP.

What are the symptoms of high ESR/CRP?

By itself, a high ESR or CRP doesn't cause any symptoms. But the conditions that lead to high ESR/CRP will usually cause symptoms.

In autoimmune diseases, those symptoms may include:

• Pain

• Fatigue

• Rashes

• Eye problems

• Joint swelling

In infection, the symptoms may include fever. It's hard to give a list of specific symptoms. That's because there are many varied conditions that can cause high ESR and CRP levels.

When will your doctor order an ESR or CRP test?

ESR/CRP can be useful in a few situations, but rarely alone:

• When combined with a physical examination and imaging, it can help establish a diagnosis.

• It reflects disease activity in some autoimmune conditions. Comparing pretreatment and posttreatment levels can help determine whether a treatment is working.

• Decreasing ESR/CRP can indicate improvement of a chronic infection.

• Research is ongoing, but ESR/CRP may help suggest a prognosis in certain chronic conditions.

How can I reduce my ESR and CRP?

An ESR/CRP that's raised due to an acute process (like a minor infection or injury) will reduce on its own once the infection or injury resolves. You don't need to do anything for the number to improve.

A chronically elevated ESR/CRP is different, and treatment may be necessary to reduce the ESR/CRP back into the normal range. Here are some ways that medications can be used to combat high inflammation:

• Target the inflammation directly: Some medications, like steroids and NSAIDs, work to reduce inflammation that's acutely causing discomfort. They work in the short term, but they usually don't solve the underlying cause of the inflammation.

• Treat the underlying disease: Other medications can decrease ESR/CRP by treating the underlying cause of the inflammation. For example, disease-modifying antirheumatic drugs (DMARDs) can treat autoimmune diseases. And antibiotics can treat serious infections.

There's a lot that's still not fully understood about chronic inflammation. It's likely to play a role in much more than we can grasp at the present - from early childhood trauma and gut health to cardiovascular disease and more.

New research is being done to explore how lifestyle changes, in addition to medical treatment, can be used to reverse chronic inflammation. For example, it's possible that diet changes could help. One review explored how eating fresh, unprocessed foods may reduce chronic inflammation. Another new study found a link between social isolation and elevations in inflammatory markers. This suggests that staying connected with people around you could potentially lower your risk of chronic inflammation.

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