What Is a Rheumatoid Arthritis Latex Turbid Test?

What to Expect When Undergoing This Test

A rheumatoid arthritis (RA) latex turbid test is a laboratory test used to help your doctor diagnose rheumatoid arthritis or another autoimmune disease. This test is sometimes called a rheumatoid factor (RF) test.

The latex turbid test uses an RF antibody that is attached to a latex bead to check for the presence of RF in the blood or joint fluid. This article explores the latex turbid test, including its purpose, risks, and contradictions; what to expect before, during, and after the test; and what results mean.

Blood draw

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Purpose of the Test

Autoimmune diseases are the result of the immune system attacking healthy tissues in the body by mistake. In RA, the immune system attacks joints, leading to joint inflammation. Ongoing and untreated inflammation will eventually cause joint damage, deformity, and even loss of joint function.

Many people with RA produce a type of antibody called RF found in the blood or joint fluid. According to the Arthritis Foundation, RF develops in up to 80% of people with RA.

Sometimes, RF levels are not detectable in early RA, but most people with the condition will eventually have high detectable levels in their blood. Other autoimmune diseases that cause high RF levels include systemic lupus erythematosus (SLE), scleroderma, Sjögren's syndrome, and vasculitis.

RF also can be associated with aging, malignancy, chronic infections (especially hepatitis C), and chronic fibrosing lung conditions.

Doctors will order an RA latex turbid blood test if they suspect you have RA. They might suspect RA if you have reported symptoms commonly seen in people with RA, including joint stiffness, swelling, tenderness, and weakness; chronic fatigue; or skin lumps.

The RA latex turbid blood test is similar to other blood panel tests that measure the amount of RF antibodies found in blood work. Generally, antibodies are produced by the immune system to stop viruses or bacteria from invading the body. RF antibodies have the opposite effect because they are doing the invading and attacking of healthy tissue.

A high RF result in an RA latex turbid test may be caused by many different autoimmune diseases or infections, including RA. It is also possible for someone who does not have an autoimmune disease to have elevated RF levels.

A person with RA might also test negative for RF. If this is the case for you, your doctor will request further testing and imaging to help make a diagnosis. Additional blood work might include an antinuclear antibody (ANA) panel, C-reactive protein (CRP) test, erythrocyte sedimentation rate (ESR), and a complete blood count (CBC).

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Risks and Contraindications

Serious complications from blood tests are extremely rare. Most complications are minor and will go away after the test is over.

It is possible to experience bruising in the area of the blood draw site. Putting pressure on the needle site for a few minutes after blood is drawn can reduce this occurrence.

Some people might experience a problem called phlebitis. This is when a vein swells after a blood sample is taken. If this happens, a cold pack can bring the swelling down.

If you have a needle or blood phobia, a condition that might affect your blood’s ability to clot, or other concerns, let the phlebotomist (the person drawing the blood) know before the blood draw starts.

Before the Test

There is no preparation needed for the RA latex turbid blood test, but you may wish to talk to your doctor about any concerns you have regarding the test and what the results might mean.

Blood tests generally take only a few minutes once the phlebotomist is ready to see you. The latex turbid test can be done at any time of the day.

There are no food, drink, or medication restrictions for this type of blood test. However, you should check with your doctor if there is anything you might need to do or avoid before the blood test, especially if you are getting other blood work done.

The latex turbid test can be performed at a hospital, clinic, or laboratory. Your doctor will tell you where you need to go to get your blood drawn. You should wear a short-sleeved shirt or a shirt where the sleeves can easily be pushed up so the phlebotomist can access your arm.

Your insurance company can give you more information on costs or any co-pays or deductible amounts you need to meet before it will cover the cost of lab work or other RA testing. Contact your insurer for more information. You should bring your insurance card with you to the laboratory.

During the Test

The RA latex turbid test is simple and quick. The phlebotomist will take a blood sample from your vein, then send it to a lab for testing. If your doctor has requested other blood work, more than one sample of your blood will be taken.

The person drawing the blood will start by wrapping an elastic band around your upper arm and tying it off to stop blood flow, making the veins below the band larger and easier to insert a needle into. The band will be removed once the draw has begun or the phlebotomist has all the blood needed.

The needle is then put into the vein. That needle is attached to a blood tube holder and an air-evacuated tube (to help pull the blood from the vein).

Once the blood draw is complete, the phlebotomist will apply a cotton ball to the draw site and gently remove the needle. Pressure is then applied to stop any bleeding, and finally, a bandage is placed over the area where the needle was inserted.

After the Test

After the latex turbid blood test, you can go home and go about your day. If you experience any pain, swelling, or bruising at the blood draw site, use a cold pack to help reduce your discomfort. A cold pack can be applied for 10–15 minutes every three to four hours. Make sure you place a layer of fabric between your skin and the cold pack.

You can use a warm compress or heating pad after 48 hours to relieve any additional discomfort and to promote healing. Contact your doctor if home treatment doesn't resolve swelling, pain, and bruising.

When the blood sample arrives at the lab, the lab technician will test the blood using a small latex bead. The bead has RF-specific antibodies attached to it. When the antibodies on the bead attach themselves to the RF in your blood, they will bind together.

The process will also cause a change in the amount of light that travels through the particles. This change is called turbidity, and high turbidity detects the RF antibody in the blood.

Interpreting Results

According to the Hospital for Special Surgery, a normal RF range is from 0–20 international units per milliliter (IU/mL). A value higher than 20 IU/mL might indicate the presence of RA or another autoimmune disease. Elevated RF levels also can occur in people with infections, liver diseases, and some types of cancer.

The higher a person's RF value is, the more likely that person has RA. Higher RF levels also may indicate a greater severity of disease in people with RA. This means having higher RF levels increases your risk for non-joint effects of RA, such as rheumatoid nodules and rheumatoid lung disease.

It is quite possible to have a high RF value and not have RA. This can occur when other conditions are causing elevated RF levels. And some people who have RA might have normal RF levels. If your doctor suspects this is the case for you, they will request additional testing, including an anti-cyclic citrullinated peptide (anti-CCP) antibody test.

Research shows the anti-CCP test is a more accurate test for diagnosing RA than the latex turbid test. Anti-CCP is a kind of autoantibody. Autoantibodies are antibodies that work against your body rather than protect it. Anti-CCP is often produced in people with RA, and it is known for targeting healthy tissues.

If the RA latex turbid test shows a normal or a lower high range RF value, your doctor will likely request additional testing to confirm or rule out RA.

A Word From Verywell

It might take a day or two before your doctor gets the results of your RA latex turbid test. It is important to note that regardless of the results of this test, the latex turbid test isn’t enough to diagnose RA.

Your doctor will rely on your medical history, including symptoms, family history (RA has a genetic component), a physical exam, imaging, and other blood work to reach an accurate diagnosis.

You should let your doctor know if you are experience signs and symptoms of RA. Your doctor will work with you to determine the source of your symptoms. If you are diagnosed with RA, you will discuss a treatment plan with your doctor, who will provide you with information about RA and what you can do to prevent joint damage or disability. 

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Article Sources
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