An autoantibody is known as immunoglobulin M (IgM) protein is produced by the immune system of the body. This autoantibody is known as Rheumatoid Factor. It is abbreviated as RF. Unlike other antibodies in a human body where the antibodies produced help to destroy the bacteria and viruses, Rheumatoid factor on the contrary results in damage when attached to a healthy body tissue. Rheumatoid factor antibody is not present in every human body. This is why the test of Rheumatoid-Factor-IgM-Antibody is essential to know the presence of it in the body of the patient. Rheumatoid arthritis is caused due to persistent inflammation of the joints of the body, destruction of the joint tissues. It is the Rheumatoid-Factor-IgM-Antibody test that aids in the diagnosis of Rheumatoid arthritis. Through Rheumatoid factor IgM antibody test, the Rheumatoid factor in the blood is measured. Doctors order for a Rheumatoid-Factor-IgM-Antibody test when the patient shows signs of pain, swelling or morning stiffness in the nodules under the skin or joints. The patient may also undergo the test when the x-ray report states loss of cartilage and bone or swollen joint capsules.