Diagnosing Arthritis (Cont.)

 
Blood Tests
There are many different blood tests that your healthcare provider may recommend based on the results of the medical history, physical exam, and x-rays.
 
Some of these tests may include common laboratory tests such as a white blood cell count or a blood test for anemia.
 
Other blood tests that may be recommended include:
 
  • Rheumatoid factor (RF)
  • Antinuclear antibody (ANA)
  • Erythrocyte sedimentation rate
  • HLA-B27.
     
Rheumatoid Factor
One test for arthritis looks for rheumatoid factor, which is an abnormal antibody (a special protein made by the immune system that normally helps fight foreign substances in the body). If a patient's test results are positive, he or she may have some form of arthritis, such as rheumatoid arthritis or lupus arthritis.
 
Antinuclear Antibody
Antinuclear antibody is another type of abnormal antibody that can be found in the blood of people with certain types of arthritis. These types of arthritis can include juvenile rheumatoid arthritis, rheumatoid arthritis, and lupus arthritis. Having a positive ANA does not necessarily mean that you have some form of arthritis. Many healthy people will have a positive ANA test.
 
Erythrocyte Sedimentation Rate
Doctors also may order a blood test to determine the erythrocyte sedimentation rate (sed rate), which is the rate at which red blood cells settle to the bottom of a test tube of blood. A high sed rate often indicates inflammation somewhere in the body. Typically, people with rheumatic diseases, including arthritis, have an elevated sed rate.
 
HLA-B27
Your healthcare provider may order a blood test to detect the genetic factor HLA-B27. HLA-B27 may be present in certain conditions known as spondyloarthropathies. Spondyloarthropathies are a family of joint diseases that can cause inflammation throughout the body. They are characterized by a positive HLA-B27 and negative rheumatoid factor. Some examples of spondyloarthropathies include:
 
(Diagnosing Arthritis Continued: Page 3)

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Written by/reviewed by: Arthur Schoenstadt, MD
Last reviewed by: Arthur Schoenstadt, MD