Rheumatoid Factor (RF)


Last Updated December 20th, 2021

What is Rheumatoid Factor or RF?

Rheumatoid factor or RF is an antibody or protein that is found normally in our body. The protein binds itself to other antibodies and so it is often referred to as autoantibody. The protein is produced by our immune system and is responsible for many diseases and the most common being rheumatoid arthritis. According to research, about 80% of older adults suffer from rheumatoid arthritis or RA with a very little fraction among children.

What is a Rheumatoid Factor test?

The rheumatoid factor or RF test is mostly used to diagnose rheumatoid arthritis. The test measures the amount of RF in your blood. It can also be used to detect other diseases like autoimmune disorders, juvenile arthritis, cancer, and infections.

Does the Rheumatoid Factor test have any other name?

The other name of the rheumatoid factor test is the RF blood test.

When do I need a Rheumatoid Factor (RF) test?

Your doctor may ask you to do a rheumatoid factor or RF test if you have the following symptoms:

Joint swelling.
– Pain in the joints.
– Stiffness in joints, especially early in the morning.
– Weakness or fatigue.
– Low fever.
– Skin nodules.
– Loss of bone or cartilage.
– Warmth and tenderness on the bones.
– Dry mouth or eyes.
– Pain in the chest while breathing.
– Spongy joints and numbness.
– Deformity of joints due to prolonged illness.

Why do I need this test?

The most likely reason for a rheumatoid factor test is to detect rheumatoid arthritis. Your doctor may also ask you to do an RF test if he suspects if you have Sjögren syndrome. High levels of rheumatoid factor can indicate several medical conditions such as:

– Cirrhosis of the liver.
– Cryoglobulinemia or a condition where there are abnormal levels of protein in the blood.
– Chronic infections like tuberculosis or mononucleosis.
– Dermatomyositis
– Lupus
– Cancer
Chronic lung disease.
– Hepatitis
– Influenza
– Leukemia
Multiple Myeloma

How will I prepare for the test?

The test is quite simple and there are no special preparations for this test.

Do I need to fast before the test?

You need not fast before the test. However, if you are doing some other blood tests, your doctor may ask you not to eat or drink anything before the blood test.

What happens during a Rheumatoid Factor test?

The rheumatoid factor or the RF test is a blood test wherein a blood sample is taken from the upper part of your arm. For it, you will be asked to:

– Sit in a comfortable position and wear a half-sleeved top or shirt.

– The technician will clean an area of your skin with an antiseptic solution.

– An elastic band or tourniquet will be tied around your arm. This will make the veins visible.

– A needle is inserted into the vein.

– The blood is withdrawn and collected to a vial or syringe.

-The puncture site is pressed with a cotton swab or a band-aid is applied to the spot.

The blood sample is then sent to the laboratory for testing for the RF antibody.

How will I feel during the test?

You will feel mild to moderate pain or a slight stinging sensation during the blood test. It will go away after a few minutes.

How long will the test take?

The test will be over within a few minutes.

When will I get my test results?

The test results will be delivered within 2 to 3 days. It depends on the laboratory conducting the test.

What is the average cost of a Rheumatoid Factor test in India?

The average cost of the test can be anywhere between Rs 400 to Rs 650 depending on the city and the laboratory performing the test.

What are the risks of this test?

The rheumatoid factor test is very simple and does not generally pose any risks. You may have little bruising or pain in the area of the puncture site, but it will go away quickly. Complications are very rare, but some people may experience some side effects such as:

– Bleeding from the puncture site.
– Bruising at the site of puncture
– In rare case, infection at the site of needle insertion
Some individuals may get anxious during the procedure and experience fainting or slight dizziness while the blood is withdrawn. In such cases, they should inform the technician or the health care provider taking the blood.

The veins may also vary in size. In some people, the veins are not easy to find and the technician might have difficulty drawing the blood. In rare cases, an infection can occur at the puncture site. Patients must immediately report that to their doctor who may prescribe some medications for relief of the symptoms.

What is the normal range for Rheumatoid Factor?

TypeRange(IU/ml or International Units per Milliliter)
Rheumatoid Factor (RF) Less than 14 IU/mL

A rheumatoid factor of less than 14 IU/mL is considered to be normal. In the Titer method, the normal ratio is less than 1:80 or 1 to 80.It is to be noted that the normal levels may vary slightly in different laboratories. It is prudent to talk to your doctor who will explain to you the meaning of your test results.

What does abnormal test results mean?

An abnormal test result means that you have a positive report or an RF value which is higher than the normal range. A positive test report indicates that you might have rheumatoid arthritis disease or Sjögren disorder. However, it should be remembered that a positive test result does not always mean that you have rheumatoid arthritis disease.

Your doctor will take into account several other factors and do several other tests before doing the prognosis. On the other hand, a negative RF report does not completely rule out the possibility of the disease. Your doctor may order other tests to get the correct diagnosis.High levels of RF can indicate several medical conditions like:

– Mixed connective tissue disease.
– Kidney disease.
– Infections like tuberculosis.
– Multiple myeloma.
– Liver disease.
– Lung disease.

What other tests can be ordered along with the Rheumatoid Factor test?

Your doctor may order some other blood tests along with this test to get a better prognosis of the disease.

– ANA or anti-nuclear antibody test.
Anti-CCP or anti-cyclic citrullinated peptide test.
– CRP or C-reactive protein test.
– ESR or erythrocyte sedimentation rate test.

Can the Rheumatoid Factor test be done during pregnancy?

Pregnant women with rheumatoid arthritis can develop a lot of complications during pregnancy or after delivery. They can develop pain and stress on hips, joints, and back as the baby develops. A reduction in milk production can also occur after delivery. A rheumatoid factor test is necessary for RA positive patients to control the disease and to provide relief to the patient.

Can the test be done in children?

Juvenile Rheumatoid Arthritis or JRA often referred to as Juvenile Idiopathic Arthritis or JIA is an autoimmune disorder that is quite common in children below 17 years of age. It can trigger many symptoms like joint pain and inflammation, stiffness, and even can affect the child’s overall growth.

If your child is JRA positive, your doctor may ask you to do several tests including the rheumatoid factor test, which is the most common tool to diagnose rheumatoid arthritis.

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