Diagnosing Polymyalgia Rheumatica
When diagnosing polymalgia rheumatica, a doctor will consider the patient's medical history and results of laboratory tests. The most common lab tests used for diagnosing this condition include erythrocyte sedimentation rate and rheumatoid factor. If the diagnosis is still unclear after performing these tests, the physician may conduct additional tests to rule out other disorders.
No single test is available to definitively diagnose polymyalgia rheumatica. To make a diagnosis of this condition, a physician considers the patient's medical history, including symptoms that the patient reports, and results of laboratory tests, which can rule out other possible diagnoses.
Certain lab tests may be recommended for diagnosing polymyalgia rheumatica. Common lab tests include an erythrocyte sedimentation rate and rheumatoid factor.
Erythrocyte Sedimentation Rate
The most typical laboratory finding in people with polymyalgia rheumatica is an elevated erythrocyte sedimentation rate, commonly referred to as the sed rate. This test measures how quickly red blood cells fall to the bottom of a test tube of unclotted blood. Rapidly descending cells (an elevated sed rate) indicate inflammation in the body. While the sed rate measurement is a helpful diagnostic tool, it alone does not diagnose polymyalgia rheumatica. An abnormal result indicates only that tissue is inflamed, which also is a symptom of many forms of arthritis and other rheumatic diseases.
Before making a diagnosis of polymyalgia rheumatica, the doctor may perform additional tests to rule out other conditions, including rheumatoid arthritis, because symptoms of polymyalgia rheumatica and rheumatoid arthritis can be similar.
The doctor may recommend a test for rheumatoid factor (RF). RF is an antibody sometimes found in the blood. (An antibody is a special protein made by the immune system.) People with rheumatoid arthritis are likely to have RF in their blood, but most people with polymyalgia rheumatica do not.
If the diagnosis still is unclear, a physician may conduct additional tests to rule out other disorders.