Blood Tests

What they tell: Physicians use several blood tests to help them diagnose some types of arthritis, particularly rheumatoid arthritis, gout and systemic lupus erythematosus (SLE). However, while blood tests are helpful, they are not diagnostic in rheumatological diseases.

Erythrocyte sedimentation rate (ESR)

This test measures how fast red blood fall or form sediment at the bottom of a glass tube full of whole blood when allowed to remain still for an hour. Individuals who have inflammation due to arthritis usually have higher sedimentation rates than others. The normal sedimentation rate is 0 to 6 mm at the end of one hour, based on Westegren Method. Upon improvement, the sedimentation rate usually decreases.

Antibody Tests

Antibodies are special kind of blood proteins to attach the antigens and render them harmless. Some abnormal antibodies - which causes harm to body cells - in the blood may suggest certain forms of arthritis. For example, persons who have rheumatoid arthritis usually have large amounts of a substance called rheumatoid factor (RF) in their blood, which is not present in a normal, healthy body. Thus the test known as the rheumatoid factor (RF) test or RA latex test helps physicians diagnose rheumatoid arthritis.

Another test for abnormal antibodies is the antinuclear antibody test (ANA), which detects a group of auto antibodies in the blood serum that are found in people who have lupus and scleroderma and in some people who have rheumatoid arthritis. One antinuclear antibody, known as anti-DNA, is particularly useful in diagnosing lupus.

Complement Test

The complement test measures the amount of complement - a substance in normal serum that is destructive to bacteria and other cells in the blood. In simple terms, complement involves a group of blood substances that help antibodies fight disease-causing agents that enter the body by promoting inflammation. Some people who have active lupus often have lower than normal amounts of complement.

Uric Acid Test

The uric acid tests measures the amount of uric acid in the blood. People who have gout usually have elevated levels of uric acid (hyperuricemia). The normal level is 3.0 to 6.0 mg/dl ml in blood serum.

Urine Tests

Urine tests (urinalysis) show whether the urine contains red blood cells, protein, or a variety of abnormal substances which are normally not present in a healthy body. Detection of these substances may help the physician diagnose kidney damage in certain rheumatic diseases, such as lupus, as well as the side effects of some drugs used -in treating arthritis.