1010 - Progressive Extremity Weakness in a Woman Found to Have HMG-CoA Reductase Antibody: A Case Report

The patient presented to the emergency department with progressively worsening bilateral lower extremity weakness, which she reported had been evolving over the past 4–5 years. She also experienced a new episode of bilateral upper extremity numbness, prompting her visit. Notably, she had restarted atorvastatin 7 months prior. Laboratory evaluation revealed an elevated creatine kinase (CK) of 4,899 U/L, AST of 208 U/L, and ALT of 201 U/L. Neurology was consulted, and the patient underwent evaluation for inflammatory myopathies. Muscle biopsy revealed necrotizing myopathy. Further serologic testing was positive for anti-HMG-CoA reductase antibodies, consistent with statin-associated autoimmune myopathy (SAAM).

Discussions:

SAAM is a rare autoimmune condition associated with the presence of anti-HMG-CoA reductase (HMGCR) antibodies and is estimated to occur in 2–3 per 100,000 statin-treated individuals. Unlike self-limited statin-induced myotoxicity, SAAM persists despite discontinuation of the statin and often requires long-term immunosuppressive therapy.

Conclusions: SAAM differs from statin intolerance or toxicity in that it represents a true autoimmune process, necessitating immunosuppressive therapy alongside discontinuation of the statin. Ongoing lipid management should be addressed using non-statin agents, such as PCSK9 inhibitors.