Quality and Patient Safety Articles-Statins and Immune-Mediated Necrotizing Myopathy

Statins and Immune-Mediated Necrotizing Myopathy

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This document discusses the differentiation between toxic necrotizing myopathy (TNM) and immune-mediated necrotizing myopathy (IMNM) in patients taking statins. TNM and IMNM can both result in severe muscle pain and weakness, but IMNM requires treatment with immunomodulatory therapy while TNM typically resolves with statin discontinuation. To differentiate between the two conditions, several factors are considered.<br /><br />Elevated CK levels and myalgias are commonly observed with statin therapy, but severe muscle pain and weakness may indicate TNM or IMNM. An irritable myopathy on EMG and necrotic muscle fibers on muscle biopsy can be seen in both conditions. However, the presence of complement membrane attack complex deposition on non-necrotic myofibers and capillaries suggests IMNM.<br /><br />The most helpful factor in differentiating TNM from IMNM is the presence of anti-HMG-CoA-reductase antibodies, which are specific to IMNM and are not usually present in TNM. Therefore, testing for the presence of these antibodies is recommended in patients with suspected statin-induced myopathy.<br /><br />Several supporting articles are listed for further reading, including those discussing toxic myopathies, immune-mediated myopathies, risk factors for statin-related myopathy, successful therapeutic strategies for anti-HMGCR myopathy, and clinical features related to statin-associated muscle symptoms.<br /><br />The authors of this document are Nida G. Gleveckas-Martens and Gregory Gruener.

Keywords

toxic necrotizing myopathy

immune-mediated necrotizing myopathy

TNM

IMNM

muscle pain

muscle weakness

statins

immunomodulatory therapy

CK levels

myalgias