What Is Rheumatoid Factor (RF)?
Rheumatoid factor (RF) is a protein produced by immune system that can attack healthy tissue in the body. Healthy individuals normally don’t produce RF, so the presence of RF in the blood can indicate to have an autoimmune disease, such as rheumatoid arthritis
How many people have rheumatoid arthritis?
According to CDC, about 1.5 million Americans have rheumatoid arthritis. RA is an autoimmune disease. The body's immune system attacks the synovial tissue between the joints, mistaking it for foreign invaders like bacteria and viruses.
Rheumatoid arthritis is a long-term condition that causes pain, swelling and stiffness in the joints. The symptoms usually affect the hands, feet and wrists. There may be periods where symptoms become worse, known as flare-ups or flares.
A flare can be difficult to predict, but with treatment it's possible to decrease the number of flares and minimise or prevent long-term damage to the joints. Some people with rheumatoid arthritis also experience problems in other parts of the body, or more general symptoms such as tiredness and weight loss.
Causes of rheumatoid arthritis
Rheumatoid arthritis is an autoimmune disease. This means your immune system – which usually fights infection – attacks the cells that line the joints by mistake, making the joints swollen, stiff and painful. Over time, this can damage the joint itself, the cartilage and nearby bone.
It's not clear what triggers this problem with the immune system, although you're at an increased risk if:
#you are a woman
#you have a family history of rheumatoid arthritis
more information about Rheumatoid Arthritis at
What happens in a joint affected by rheumatoid arthritis?
Rheumatoid arthritis causes inflammation in the synovium. The result is very similar to inflammation that you may have seen if you’ve had an infected cut or wound – it goes red, swells, produces extra fluid and hurts. The redness is caused by the flow of blood increasing. As a result, the inflamed joint may feel warmer than usual. The inflammation is caused by a build-up of fluid and cells in the synovium. Your joint hurts for two reasons:
#Your nerve endings are irritated by the chemicals produced by the inflammation.
#The capsule is stretched by the swelling in your joint.
When the inflammation goes down, the capsule remains stretched and can’t hold your joint in its proper position. This can make your joint unstable, and it can move into unusual or deformed positions. Some damage is done to the joints every time they're inflamed, and the joint can be worn away after repeated flare-ups (periods where your joints become inflamed and painful).
What are the symptoms of rheumatoid arthritis?
Symptoms of rheumatoid arthritis tend to come and go. You may have flare-ups when your symptoms become worse than normal. Common symptoms of rheumatoid arthritis include:
#joint pain and swelling
#tiredness (fatigue), depression, irritability
#flu-like symptoms, such as feeling generally ill, feeling hot and sweating.
Rheumatoid arthritis varies from one person to another but it usually starts quite slowly. A few joints – often your fingers, wrists or the balls of your feet – become uncomfortable and may swell, often intermittently. You may also feel stiff when you wake up in the morning.
Research shows that the sooner you start treatment for rheumatoid arthritis, the more effective it’s likely to be, so early diagnosis is important. For about 1 in 5 of those with rheumatoid arthritis the condition develops very rapidly, with pain and swelling in a lot of joints, severe morning stiffness and great difficulty doing everyday tasks. You may feel tired, irritable or depressed even when the joint symptoms are fairly mild, and some people feel generally unwell.
How is TEST used?
The rheumatoid factor (RF) test is used to help diagnose RA and to distinguish it from other forms of arthritis and other conditions that cause similar symptoms of joint pain, inflammation, and stiffness.
Cyclic Citrullinated Peptide Antibody (CCP) test is primarily ordered along with an RF test when someone has signs and symptoms that may be due to previously undiagnosed inflammatory arthritis or has been diagnosed with undifferentiated arthritis. It may be ordered as a follow-up test to a negative RF test when clinical signs and symptoms lead a health practitioner to suspect RA.
Patients with rheumatoid arthritis can have positive tests for either RF or CCP or may have both antibodies detected.
When is it requested?
The test for RF may be requested when a patient has signs of RA and these have persisted for more than weeks. Symptoms may include pain, warmth, swelling, and morning stiffness in the joints, nodules under the skin, and, if the disease has progressed, evidence on X-rays of swollen joint capsules and loss of cartilage and bone. An RF test may be repeated when the first test is negative and symptoms persist.
What does the test result mean?
When people with signs and symptoms of arthritis are positive for both CCP antibody and RF, it is very likely that they have RA and it is likely that they may develop a more rapidly progressive and severe form of the disease.
When people are positive for CCP antibody but not RF, and have clinical signs that suggest RA, then it is likely that they have early RA or that they will develop RA in the future.
1. Take out the kit and put it at room temperature for 20-30min;
2. Dispense 1 drop of wash buffer to the test window,waiting for the liquid to wet the membrane well;
3. Add 150ul of serum(4 drops if with a sample pipet)into the test window,waiting for the liquid to be absorbed completely;
4. Add 3 drops of colloidal Gold Conjugate into the test window,waiting for the liquid to be absorbed enough;
5. Add 3 drops of wash buffer into the test window,and interpret the result within 3 minutes immediately after the liquid is absorbed adequately.
Note1: This is SERUM / plasma TEST only,
You need to be able to separate SERUM / plasma from blood, to perform RF test.