One blood test called FM/a can help identify markers produced by blood cells in people with fibromyalgia, but it is not conclusive on its own. A physician generally diagnoses fibromyalgia through physical examination and discussing symptoms with the patient, according to WebMD.
If a physician suspects fibromyalgia, the patient may also undergo blood tests to rule out more serious conditions since fibromyalgia symptoms may mimic other diseases like inflammatory arthritis and lupus. The doctor may order a complete blood count, electrolyte sedimentation rate and thyroid function tests to determine if other conditions are present, states Mayo Clinic.
Generally, a doctor can diagnose fibromyalgia using certain diagnostic guidelines. If the patient has had widespread pain in all quadrants of the body for at least three months and there are no other diseases present that could cause the pain, the doctor may conclude a diagnosis of fibromyalgia, reports WebMD.