The HLA-B27 test is a diagnostic tool used by physicians to support or rule out certain disorders of the autoimmune system, according to the American Association for Clinical Chemistry. Patients who present with joint pain and stiffness may be tested for the HLA antigen, says Healthline. Widespread pain is a symptom of fibromyalgia, explains Mayo Clinic.
The HLA-B27 test checks for the presence of human leukocyte antigen on the surface of white blood cells. The presence of HLA protein can trigger the body's immune system to attack healthy tissue as if it were a foreign substance. The HLA-B27 test may be used to monitor progression of a diagnosed autoimmune disorder, notes Healthline.
Other tests used to rule out or confirm diagnosis of autoimmune disorders include ESR blood sedimentation tests, ANA antinuclear antibody tests, CRP reactive protein tests and RF blood tests to confirm the presence of rheumatoid factor, states the American Association for Clinical Chemistry.
Fibromyalgia is a syndrome that presents several simultaneous symptoms. There is no definitive blood test for fibromyalgia. Fibromyalgia pain occurs throughout the body on both sides. Patients with fibromyalgia may oversleep and feel unrefreshed when they wake. They may suffer chronic fatigue, anxiety and widespread pain. Depression may also be present, according to WebMD.