Investigations
1st investigations to order
erythrocyte sedimentation rate (ESR)
Test
Normal values of ESR vary with age. ESR is elevated in 91.5% of patients at diagnosis but is not as sensitive as a CRP, which is elevated in 98.9%. An elevated ESR at diagnosis is associated with a higher risk of more than 1 relapse.[28][29] Abnormal levels are more common in males.[30]
Normal ESR in patients with PMR may indicate a milder subset of disease or identification of patients earlier in their disease course.[19]
Result
elevated
C-reactive protein (CRP)
Test
A sensitive indicator of disease activity, which is elevated in 98.9% of patients diagnosed with PMR.[28][31][32] Unlike the ESR, the pre-treatment levels of the CRP are not prognostic. However, persistently elevated levels of CRP despite treatment are associated with higher rates of relapse.[29][33]
Normal CRP in patients with PMR may indicate a milder subset of disease or identification of patients earlier in their disease course.[19]
Result
elevated
FBC
Test
As some myeloproliferative diseases may also present similarly to PMR with symptoms of fatigue and bony pain and an elevated ESR, checking an FBC and serum protein electrophoresis is also recommended as part of PMR evaluation.
Result
variable
Investigations to consider
TSH
Test
TSH may be elevated if hypothyroidism is the cause of symptoms
Result
normal or raised in hypothyroidism
ultrasound
MRI
Test
More sensitive than ultrasound, but not routinely done.[4][22]
Subdeltoid bursitis, bicipital tenosynovitis, glenohumeral synovitis and/or hip synovitis are characteristic of PMR.[11] Trochanteric bursitis is present in many patients with PMR.[22] Interspinous bursitis may be detected on MRI.[23]
Result
bursitis, tenosynovitis, synovitis, joint effusions
serum protein electrophoresis
Test
As some myeloproliferative diseases may also present similarly to PMR with symptoms of fatigue and bony pain and an elevated ESR, serum protein electrophoresis is also recommended as part of PMR evaluation.
Result
normal in PMR
rheumatoid factor
Test
Performed if early rheumatoid arthritis is suspected. The presence of an inflammatory arthritis involving the finger joints (particularly the PIP and MCP joints) is an indication to check rheumatoid and anti-cyclic citrullinated peptide antibody titres.[20]
Result
usually normal
anti-cyclic citrullinated peptide antibodies
Test
Performed if early rheumatoid arthritis is suspected. The presence of an inflammatory arthritis involving the finger joints (particularly the PIP and MCP joints) is an indication to check rheumatoid and anti-cyclic citrullinated peptide antibody titres.[20]
Result
normal
Emerging tests
interleukin (IL)-6
Test
IL-6 stimulates many acute phase proteins. Elevated IL-6 is characteristic in PMR. Although an elevated level can be a sensitive marker for PMR disease activity and supportive of the diagnosis, it is not yet specific enough to be used as a diagnostic test. Persistently elevated levels of IL-6 despite treatment are associated with higher rates of relapse.[29]
Result
elevated
fluorodeoxyglucose F-18 PET scan
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