Investigations
1st investigations to order
clinical diagnosis
Test
There is no x-ray or laboratory testing for fibromyalgia; the diagnosis is strictly clinical.[95][106]
If the patient does not meet clinical criteria for a diagnosis of fibromyalgia, then some tests should be performed to screen for alternative causes of the symptoms.
Result
presence of chronic (>3 months), widespread body pain and associated symptoms such as fatigue and sleep disturbance
Investigations to consider
erythrocyte sedimentation rate (ESR)/CRP
Test
A normal ESR/CRP level may not be sufficient to exclude an inflammatory cause; however, makes it less likely. Similarly, fibromyalgia is not associated with elevated ESR/CRP so further evaluation should be sought if levels are elevated.
Result
likely normal
thyroid function test
Test
To exclude hypothyroidism.
Result
likely normal
FBC
Test
To exclude anaemia as a cause for fatigue or iron deficiency as a cause for muscle pain and fatigue.
Result
likely normal
rheumatoid factor
Test
An elevated rheumatoid factor level may indicate the presence of rheumatoid arthritis, and should be obtained if patients have a history suggestive of an inflammatory disorder such as symmetrical small joint pain with associated inflammatory features, and/or synovitis seen on examination.
Result
likely normal
anti-cyclic citrullinated protein (CCP) antibody
Test
An elevated anti-cyclic citrullinated protein antibody level may indicate the presence of rheumatoid arthritis, and should be obtained if patients have a history suggestive of an inflammatory disorder such as symmetrical small joint pain with associated inflammatory features, and/or synovitis seen on examination.
Result
likely normal
antinuclear antibody or anti-DNA antibody
Test
Should be obtained selectively when there is clinical suspicion of systemic lupus erythematosus based on the patient's history (i.e., uveitis, sicca symptoms, oral ulcers, rash, photosensitivity, pericarditis/pleurisy, Raynaud's syndrome, cytopenias, seizures, thrombotic complications, renal involvement) as positive results have been reported in healthy people, therefore they have poor predictive value unless there is significant suspicion of systemic rheumatic disease.[116]
Result
likely normal
vitamin D level
creatinine kinase
Test
If there is evidence of proximal/distal muscular weakness on physical examination, creatinine kinase levels should be assessed to look for evidence of an underlying myopathy/myositis.
Result
likely normal
ferritin
Test
Checking ferritin levels should be considered to look for iron deficiency, particularly as a cause of fatigue, but this can be associated with non-specific symptoms, frequently seen in similar populations such as pre-menopausal women.
Result
likely normal
overnight oximetry/polysomnography
Test
Should be considered in selected patients believed to have an elevated risk of obstructive sleep apnoea.
Result
likely positive for sleep apnoea
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