CRP Test vs ESR Test: Understanding the Differences and Significance
By Dr. Nayana Shetty +2 more
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By Dr. Nayana Shetty +2 more
Table of Contents
When we are dealing with infections, inflammation, and different diseases, laboratory tests are of great help. They aid in correctly diagnosing health concerns. Two frequently used tests, the C-reactive protein (CRP) test, and the erythrocyte sedimentation rate (ESR) test can detect inflammation1. Each of them plays a unique role in detecting inflammation and monitoring a disease. On the contrary, there are distinct differences between them2,3.
In this article, we will understand the roles and procedures of both CRP and ESR tests. We will glean insight into how they differ, their impact on medical diagnosis and management, and the typical medical situations in which they are used.

Did you know?
An important inflammation marker is the C-reactive protein or CRP8. It is produced by your liver and increases during times of inflammation. A simple blood test is the usual course to measure it.
Essentially, CRP is an acute phase reactant. Its levels rise when the body is dealing with inflammation1. This response is caused by specific proteins termed cytokines, which are produced by white blood cells in times of inflammation.
The liver plays a central role in producing CRP. The production of cytokines in response to inflammation stimulates the synthesis of CRP. This results in an increase in CRP levels in your bloodstream8.
CRP usually spikes during bouts of inflammation. This inflammation could be triggered by an infection, injury, or any chronic inflammatory disease4.
Measuring CRP levels requires a blood sample, which is then tested in a laboratory.
Blood is usually drawn from a vein. The vein is searched for on the inner side of your elbow or the back of your hand. A needle is pricked into the vein, and the blood is then collected either in an air-tight vial or a syringe.
Once your blood sample is collected, it is sent to a laboratory. The laboratory technicians determine CRP concentrations. This gives a clearer picture of the level of inflammation in your body8,9.
The way to interpret CRP test results is described below.
CRP levels depend on age, gender, and even ethnic background. In healthy grown-ups, CRP mainly stays below 0.3 mg/dL. Low CRP doesn’t always mean no inflammation. Some people with conditions like rheumatoid arthritis might show normal CRP5,11.
An upsurge in CRP may suggest different conditions like cancer, heart attack, infection, IBD, and autoimmune illnesses such as rheumatoid arthritis and lupus. It’s worth noting that high CRP itself can’t pin down the exact cause of inflammation4,9,10.
Several factors can sway CRP levels. Some of them are pregnancy, birth control pills, and certain medications. Therefore, it’s crucial that you talk about any personal conditions with your healthcare provider when reading CRP test results8.
The erythrocyte sedimentation rate (ESR) is another inflammation marker2,3. This test checks how fast red blood cells (erythrocytes) settle at the bottom of a tube.
When our bodies fight inflammation, red blood cells may clump together. They get heavier and settle faster in a tube. The farther these cells sink within the hour, the higher the inflammatory response2.
ESR can be influenced by factors like age, anaemia, pregnancy, kidney problems, thyroid disease, certain cancers, infections, and injuries3.
ESR test also needs a regular blood sample for laboratory testing, much like the CRP test.
For this test, blood is drawn from a vein, usually inside the elbow or back of your hand. This sample is placed in a tall, thin tube for the ESR analysis.
This test gauges how far red blood cells fall in the tube within an hour. The greater the distance they cover, the higher the inflammation2,3.
ESR interpretation is similar to CRP where several factors need to be considered. Different conditions can play with ESR values, making it essential to keep them in mind while interpreting the results.
Like CRP, ESR also depends on factors like age and gender. Usually, men show ESR up to 15 mm/hr, while women may have up to 20 mm/hr2.
Raised ESR levels are often found in people suffering from giant cell arteritis, polymyalgia rheumatica, rheumatoid arthritis, and infections3,11.
ESR might be swayed by factors such as anaemia, pregnancy, kidney problems, thyroid disease, certain cancers, and infections2,3.
It’s critical to note the differences and similarities between CRP and ESR tests. Both help in detecting inflammation. Understanding the nuances aid in wise medical decisions.
Both detect inflammation in our bodies. They provide an overall status of inflammation but can’t point out the exact cause or location1,2.
Despite measuring inflammation, CRP and ESR tests aren’t the same.
CRP is generally more sensitive than ESR. It responds faster to changes in inflammation. In contrast, after inflammation resolves, ESR may stay elevated for a longer time3.
Both tests assist in diagnosing different conditions. CRP is good at detecting short-term inflammation and infections. On the other hand, ESR is better at monitoring chronic inflammatory diseases like rheumatoid arthritis5,11.
When it comes to checking therapy effectiveness, CRP can give quicker feedback. ESR, along with other evaluations, helps monitor management effects on chronic conditions3.
Both tests demand a blood sample, mostly drawn from the inner elbow or back of the hand. Yet, they use different methods and aspects in measuring inflammation2.
It’s a lesser-known fact that when ESR and CRP tests are done at the same time, they tend to show similar results around 67% to 81% of the time. Since there’s no agreement on which test is better, doctors frequently ask for both CRP and ESR tests to cover all bases.
Dr. Siddharth Gupta, BAMS, MD (Ayu)
These tests come in handy in many medical situations, helping diagnose and monitor various health conditions.

CRP and ESR tests help in the diagnosis and tracking of rheumatoid arthritis, a chronic inflammatory autoimmune disease11. They work together with other tests to gauge disease activity and track the progress of management plans5.

Inflammatory bowel disease (IBD) is a long-term inflammation of the gut. Both tests play a vital role in observing disease trends and checking if therapies are working4.

High-sensitivity CRP has gained importance in predicting a person’s risk for heart issues like heart attack or stroke9. High CRP implies higher risk. It helps healthcare professionals decide possible management and steps to reduce risk8.

Unexpected inflammation or potential infections can be detected by both tests1. They provide valuable data for guiding therapy decisions and ensuring suitable care10.
In my experience, if you are suspected of mild bone and joint infections like osteomyelitis or early prosthetic joint infections, your doctor might use CRP and ESR tests results together along with other medical checks to help confirm the diagnosis.
Dr Rajeev Singh, BAMS
Knowing how CRP and ESR tests differ and match, and understanding their role in medical practice is a must for healthcare professionals. They are potent tools in detecting inflammation, guiding diagnoses, tracking diseases, and assessing the success of therapy1,2,3.
As you explore medical testing, it’s key to appreciate the unique role of each test. They work hand-in-hand to deliver the best patient care.
While both tests detect inflammation, they’re not the same. They focus on different facets and have varying sensitivity and specificity3. They are usually used together to provide a well-rounded picture of a person’s inflammation status and help with management decisions.
Both CRP and ESR test results can be affected by various factors including age, gender, ethnic background, pregnancy, medications, and other health conditions2,8. Hence, it’s important to discuss your specific conditions with your healthcare provider to avoid any or misinterpretation of results.
How frequently CRP and ESR tests should be done depends on the disease being tracked and other personal factors. The best schedule will be determined by your healthcare provider, keeping in mind your case and targets of therapy.
While drawing blood for both CRP and ESR tests, there might be minor risks. These include bruising, swelling, feeling dizzy, or infection. But, these risks are small, and most people undergo the tests without any problems.
For a CRP or ESR test, you don’t need any special preparation. Do inform your healthcare provider about any medications you’re on as some can impact the results. If you wear a short-sleeved shirt to the test, it will be easier to access your veins for the blood draw.
Disclaimer: The information provided here is for educational/awareness purposes only and is not intended to be a substitute for medical treatment by a healthcare professional and should not be relied upon to diagnose or treat any medical condition. The reader should consult a registered medical practitioner to determine the appropriateness of the information and before consuming any medication. PharmEasy does not provide any guarantee or warranty (express or implied) regarding the accuracy, adequacy, completeness, legality, reliability or usefulness of the information; and disclaims any liability arising thereof.
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