What is the role of lab testing in the workup of sporadic inclusion body myositis (s-IBM)?

Updated: Jun 08, 2018
  • Author: Michael P Collins, MD; Chief Editor: Nicholas Lorenzo, MD, MHA, CPE  more...
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Answer

Standard studies pertinent to the evaluation of patients with progressive myopathic weakness include complete blood count, magnesium, calcium, phosphate, creatinine, creatine kinase (CK), erythrocyte sedimentation rate (ESR), antinuclear antibodies, rheumatoid factor, serum protein electrophoresis (+/- immunofixation), vitamin D levels, and thyroid function tests.

CK level should be assessed prior to the EMG study. In most cases of s-IBM, serum CK level is normal or elevated to a mild-to-moderate degree. Elevation greater than 12 times normal may occur but is rare.

If polyneuropathy is present based on clinical or electrodiagnostic criteria, then screening for diabetes mellitus and other potential etiologies for a polyneuropathy should be performed.

Myositis-specific antibodies occur more rarely in s-IBM than in DM or PM, but when present, they may identify a subgroup of immunosuppressive treatment-responsive patients. [86]


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