Blood Test for Rheumatoid Arthritis: How It’s Done

Rheumatoid arthritis (RA) is a chronic inflammation that primarily affects your joints, causing aching, swelling, and pain.

An autoimmune disorder, RA occurs when your body erroneously launches an immune attack and gradually destroys tissue in the lining of your joints and other parts of the body.

This causes painful swelling that ultimately leads to joint deformity and erosion of bone density.

Unlike osteoarthritis, the impact of rheumatoid arthritis can go beyond your joints. For example, inflammation associated with RA can damage other body systems, including your blood vessels, heart, lungs, eyes, gastrointestinal tract, and skin.

According to the review of the National Arthritis Data Workgroup, roughly 1.3 million people in the US are affected by rheumatoid arthritis.

RA typically has mild to severe symptoms, most of which come and go before appearing again.

The most common symptoms include loss of joint function, stiff joints, swollen joints, and joint pain.

As with most autoimmune disorders, rheumatoid arthritis can go hand in hand with other autoimmune disorders, including type 1 diabetes, Addison’s disease, autoimmune thyroid disease (ATD), celiac disease, and more.

Like most autoimmune disorders, there’s no exact cure of rheumatoid arthritis, but your doctor can recommend treatments to keep it well-managed.

Diagnosis and Screening for Rheumatoid Arthritis

Rheumatoid Arthritis

Diagnosing rheumatoid arthritis can prove to be a difficult task for rheumatologists and doctors, particularly in its early stages. That’s because the early symptoms and signs of RA resemble those of a variety of other conditions and disorders.

For example, if you experience pain and morning stiffness in symmetrical joints, you may have rheumatoid arthritis. You could also be suffering from cancer, osteoarthritis, or just have a bad mattress.

However you look at it, rheumatoid arthritis is a diagnostic enigma as there’s no single blood test, imaging test, or physical examination that can conclusively confirm diagnosis.

Nevertheless, your physician will examine your joints for warmth, redness, and swelling during a physical check. Your doctor may also assess your muscle strength, reflexes, eyes, and other signs for autoimmune inflammation.

When all’s said and done, however, there are two key ways to diagnose or screen for rheumatoid arthritis: imaging tests and blood tests.

Imaging Tests

imaging tests

Your physician may recommend certain imaging tests to check for joint damage. These tests are two-prong, and will determine:

  (i)         If your joints have been damaged, and

  (ii)         The severity of the joint damage.

Often, X-ray tests are requested to handle the first, enabling doctors to see clearly if there is joint damage. On the other hand, ultrasound and MRI tests are recommended to check how severe the damage is in your body.

Despite this, imaging tests usually don’t tell much. In fact, they can’t be leveraged on their own to confirm a rheumatoid arthritis diagnosis.

That’s where blood tests come in handy.

In this article, we shall cover the various blood tests for arthritis and how they are done.

Blood Tests

Blood tests are typically fast and deliver more useful results than imaging tests.

Nonetheless, they don’t offer a straightforward YES-or-NO result in whether you have rheumatoid arthritis. Instead, they help your rheumatologists or physician inch closer towards a conclusive diagnosis.

More specifically, if they confirm RA, blood tests help you and your physician narrow down your treatment options, as well as tell your doctor how your RA may progress.

More importantly, ongoing blood tests will help you keep a tab on the side effects and effectiveness of your medication once you have received a diagnosis of rheumatoid arthritis.

Taking continued blood tests may also help your doctor monitor the progress of the condition and know when to change the course of treatment.

Fortunately, you don’t have to make a long trip to the doctor’s office or a lab every time you need a blood test done! imaware™ at-home blood tests make the whole process easy, painless and hassle-free, all done in under five minutes!

Common Blood Diagnostic Tests for Rheumatoid Arthritis

Blood Diagnostic Tests

Your physician will leverage numerous blood tests ⁠— usually combined with imaging tests ⁠— to help diagnose you with the disorder.

If you opt for a lab test, the technician will simply draw your blood and you can leave immediately. Your doctor will receive results after a few days.

Anyone with RA normally has high levels of C-reactive protein (CRP) or elevated erythrocyte sedimentation rate (ESR), both of which are signs of inflammatory activity in the body.

Other typical blood tests check for antinuclear, anti-cyclic citrullinated peptide (anti-CCP), and rheumatoid factor antibodies.

Let’s take a closer look at each blood diagnostic test for RA:

(1) Rheumatoid Factor (RF) Test

Rheumatoid Factor

How It is Used

Better known as an RF test, this is the most common RA blood test, and it checks for the level of rheumatoid factor in your blood.

Rheumatoid factor is a kind of protein that your body generates when your own immune system attacks healthy cells and tissue. It’s often linked to autoimmune disorders, especially rheumatoid arthritis.

An RF blood test actually screens for rheumatoid factor antibodies which usually accumulate in the joint’s synovium. The most typical form of the RF antibody is known as immunoglobulin IgM. When immunoglobulin IgM adheres to healthy tissue, it can result in damage.

An RF test is usually used in tandem with imaging tests and other lab tests to determine a diagnosis of rheumatoid arthritis. It’s rarely used on its own for a conclusive diagnosis.

Interpreting RF Results

Your RF test results will be presented as either the concentration or units per milliliter (u/mL) of the RF antibodies in your blood.

A concentration of under 1:80 RF is often taken as normal. However, if you have anything higher than this, your chances of having RA are high.

A reading of less than 20 u/mL is also considered to be a normal level of RF antibodies in your blood. Any reading higher than this indicates a positive rheumatoid factor result.

Often, the higher the concentration/units per milliliter of RF antibodies in your blood, the greater your chances that you have rheumatoid arthritis. However, RF antibodies are found in other autoimmune disorders too.

What Do the Test Results Mean?

RF test results must be used in combination with an individual’s medical history, symptoms, and signs, as well as other lab tests. It seldom stands alone in diagnosing RA.

Between 70 percent and 90 percent of people with rheumatoid arthritis have a high reading of RF. That isn’t 100% diagnostic of rheumatoid arthritis.

In patients with clinical signs and symptoms of RA, the presence of substantial amounts of rheumatoid factor shows that it’s highly likely that they have the disorder.

Often, higher levels of RF antibodies correspond with a more severe condition or poor medication. In other words, your disease will be less severe if you have a low RF count but still have RA.

Also, a negative RF test result cannot be used to rule out rheumatoid arthritis. In fact, approximately 20 percent of patients with the disorder have significantly low levels of rheumatoid factor.

In some cases, RF isn’t even detectable in their blood samples. A positive CCP antibody test is often used to confirm that someone has rheumatoid arthritis.

Other Conditions You May Have

A positive RF test can also be a sign of other conditions, including lupus, type 1 diabetes, cancer, bacterial endocarditis, or a chronic infection.

In some cases, a high RF level may mean that you have Sjogren syndrome. This is an autoimmune condition that causes dry mouth and dry eyes.

(2) Antinuclear Antibody (ANA) Test

Antinuclear Antibody

How Is It Used?

The antinuclear antibody (ANA) is an array of panel blood tests that checks your immune system to determine whether it is creating antibodies.

Antinuclear antibodies are a kind of autoantibody that an individual’s immune system produces when your body cannot tell the difference between foreign or harmful objects and healthy cells or tissue.

You see, your body responds to several different types of autoimmune conditions by making antibodies. The same is true for a person with rheumatoid arthritis.

At its core, an ANA broad-spectrum test measures or checks your blood for the presence of these abnormal antibodies or autoantibodies.

Interpreting ANA Test Results

The results of your ANA test will be reported in titer, which is the concentration of the antibodies as a ratio of the lowest mix of the solution as determined by titration.

A normal or negative result is anything lower than 1:40, which translates to one part antibodies per 40 parts solution.

A value that is higher than 1:40 is taken as a positive ANA result. In this case, you may have rheumatoid arthritis.

On top of a titer, a positive result on the ANA may include a description of the fluorescent pattern seen in the result. Various patterns have been linked to different autoimmune conditions.

For instance, a speckled pattern can mean that you have rheumatoid arthritis. However, it can also be indicative of other autoimmune disorders, including Sjögren’s syndrome, scleroderma, polymyositis, or SLE.

What Do the Test Results Mean?

A positive ANA result shows that you have autoantibodies in your blood. In individuals with clinical symptoms and signs of rheumatoid arthritis, this may be an indication that they have the disorder.

However, a positive ANA result cannot be used on its own as a reliable diagnosis for RA.

If the result of an ANA test returns negative, on the other hand, the chances are very high that you don’t have the disorder.

Other Conditions You May Have

As we’ve stated earlier, a positive ANA profile may help your physician figure out if you have other autoimmune disorders, most notably Sjögren’s syndrome, Scleroderma, SLE, and lupus.

(3) Erythrocyte Sedimentation Rate (ESR) Test

(3) Erythrocyte Sedimentation Rate

How Is It Used?

ESR is a non-specific yet cheap and simple blood test for RA.

Erythrocyte sedimentation rate refers to the hourly rate at which red blood cells (RBCs) form clumps and fall to the bed of a special glass tubing.

Some doctors may call this a sed rate, Sedimentation Rate Wintrobe, Westergren Sedimentation Rate, or simply ESR.

As you might have already suspected, your blood sample is dropped into a test tube to see how fast RBCs will float to the bottom. The proteins responsible for inflammation clump together and fall to the bottom of the test tube.

An ESR test is designed to help doctors figure out the level of inflammation in your body. The faster the sedimentation rate, the greater the inflammation, showing that you are more likely to have an autoimmune disorder.

So, the result of the test tells your physician whether inflammation is present. Interestingly, an ESR test result doesn’t tell what caused the inflammation.

However, it is usually affected by a plethora of other factors, which means that results can’t be used independently to diagnose rheumatoid arthritis.

Interpreting ESR Test Results

The results of your ESR test are normally presented as millimeters per hour. Normal ESR varies depending on age and gender.

In men 50 and younger, normal ESR value is between 0 and 15 mm/h. In those older than 50, normal ESR is under 20 mm/h.

When it comes to women, normal ESR is under 20 mm/h and 30 mm/h for those younger than 50 and those older than 50 respectively.

What Do the Test Results Mean?

Healthy people usually have low ESR. Inflamed cells are usually heavier and sink faster down the test tube.

A positive ESR result (usually a reading of above 100 mm/h) can be used in conjunction with obvious clinical signs and symptoms, as well as other blood tests, especially RF and CCP tests.

If the clinical findings and ESR match, the doctor might be able to rule out or confirm suspected rheumatoid arthritis.

When monitoring RA, rising ESR may be an indication of increasing inflammation or a poorer treatment method. Decreasing or normal ESR, on the other hand, may show that you are responding to medication.

Other Conditions you May Have

High ESRs are usually an indication of inflammation in the body, but they can’t pinpoint any specific inflammatory condition. It could point towards conditions like temporal arteritis, systemic vasculitis, and Polymyalgia rheumatica.

(4) Anti-Cyclic Citrullinated Peptide (anti-CCP) Test

anti-CCP test

How Is It Used?

This test measures anti-cyclic citrullinated peptide, a protein antibody that is typically linked to rheumatoid arthritis. This is a type of antibody that the body makes when inflammation is present.

People with anti-CCP often have RA, but not everyone with rheumatoid arthritis tests positive for this antibody. That’s why doctors order an anti-CCP test after or alongside an RF (rheumatoid factor) test to help rule out or confirm a diagnosis.

Interpreting Anti-CCP Test Results

An anti-CCP test result is usually reported as units per milliliter (u/mL) of the antibody in the blood. Normal levels of anti-CCP antibodies are less than 20 u/mL.

Higher numbers may indicate that you have rheumatoid arthritis.

What Do the Test Results Mean?

An anti-CCP test provides an avenue for doctors to potentially find rheumatoid arthritis in its formative stages. The levels of anti-cyclic citrullinated protein antibodies are normally high in persons with active RA or those individuals who are about to develop the disorder.

In a person who has shown clinical symptoms and signs of arthritis, a positive anti-CCP result means that there’s a 97 percent possibility that he or she has RA.

If the same person has a positive RF test, he or she might likely have a more severe form of the disorder.

Other Conditions You May Have

An anti-CCP test is specially designed to diagnose rheumatoid arthritis. So, if the test shows high numbers of anti-CCP antibodies, it may be conclusive of a diagnosis of RH.

(5) C-Reactive Protein (CRP) Test

C-Reactive Protein

How Is It Used?

Better known as CRP, C-reactive protein is a ring-like protein that your liver produces when inflammation occurs. A CRP test checks for the presence and levels of this protein in your blood.

C-reactive protein cannot be used on its own to confirm rheumatoid arthritis diagnosis. Instead, doctors request this test to determine the severity of the disease.

Even though more expensive, the CRP test is usually more sensitive and accurate than an EST test.

Often, a CRP (or ESR) test is ordered if you have a false negative on the rheumatoid factor (RF) test.

Interpreting CRP Test Results

The results of a CRP test are typically presented as milligrams per liter (mg/L). The level of C-reactive protein is usually low. For instance, a normal reading is anything less than 10 mg/L, but the results can vary from one lab and person to another.

What Do the Test Results Mean?

Again, normal CRP levels are often very low. Doctors usually order an ongoing CRP test to determine your risk of RA.

If your CRP levels start going up, this is typically an indication of inflammation, injury, or the presence of an autoimmune condition. The good news is that CRP levels usually rise before the symptoms or signs of the condition show up.

As such, CRP tests can help detect the disease early. Additionally, doctors leverage ongoing CRP tests to monitor disease activity and to know the progress or efficacy of medication.

Other Conditions You May Have

While this test can help diagnose RA, bacterial infection and any autoimmune condition can raise your levels of CRP. Ultimately, this can make the diagnosis of RA very complex.

If your CRP levels are high, it can indicate that you may have sepsis, heart attack, and any autoimmune disorder.

(6) Complete Blood Count

 Complete Blood Count

How Is It Used?

A complete blood count is what it sounds like – a routine test that checks the counts of your red and white blood cells.

It is further broken down into five individual blood tests:

(i) Red blood cells test, which measures the number or count of RBCs that ship oxygen from the lungs to the rest of your body.

(ii) Hematocrit test, which measures the volume of red blood in your body.

(iii) White blood cells test, which means the count of WBC which helps fend off infection

(iv) Hemoglobin test which checks your body’s capacity to carry oxygen.

(v) Platelets test which measures the count of platelets in your system. These are blood agents that help with clotting.

Interpreting Complete Blood Count Results

Blood Count Results

Hematocrit test results are reported as a percentage. Normal results range from 36-52% in men, while that for normal women ranges from 34-46%.

Red blood cell test results are presented in millions per cubic millimeter (million/mm3). The normal RBCs count ranges from 3.93 to 5.69 million/mm3.

Similarly, white blood cell counts are presented in millions per cubic millimeter (million/mm3) of total blood volume. Normal WBCs count ranges from 4.5 to 11.1 thousand/mm3.

Platelet results are reported as thousands per cubic millimeters of blood. A normal platelet count ranges between 150 and 450 thousand/mm3.

Hemoglobin test results are presented in grams per deciliter (g/dL) of blood. In men, normal hemoglobin levels range from 13.2 to 17.3 g/dL. In women, normal levels range from 11.7 to 16.1 g/dL.

What Do the Test Results Mean?

Low hematocrit and hemoglobin results can be linked to RA. However, physicians use these results to determine if your RA or its treatments are causing other health problems such as anemia.

If hemoglobin or hematocrit results are very low, it may be an indication that your medications are having side effects.

Other Conditions you May Have

Low complete blood count results may be a sign that you have an infection, leukemia, anemia, etc.

Summary

These are just but the six most common blood tests doctors order to determine if you may have rheumatoid arthritis.

Other blood tests that may be used to diagnose rheumatoid arthritis include the Cryoglobulins test, Complement test, Creatine Kinase (CK) test, HLA-B27 test, and Antineutrophil Cytoplasmic Antibodies (ANCA) test.

Because a single blood test may not confirm or rule out RA diagnosis, you may have to take several of them.

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