Two cases of statin-induced myopathy caused by induced hypothyroidism.

OBJECTIVE: To present information regarding the potential danger of performing levothyroxine withdrawal radioiodine scans and treatment in patients with thyroid cancer who are concurrently taking lipid-lowering agents.

METHODS: We review the clinical history, serial laboratory data, and radiologic findings in 2 patients with multifocal papillary carcinoma of the thyroid.

RESULTS: Both study patients had substantial elevations of muscle enzymes or myopathies (or both) when they were withdrawn from levothyroxine therapy, during treatment with lipid-lowering agents, in preparation for radioiodine scanning and treatment.

CONCLUSION: Extreme caution should be exercised when levothyroxine therapy is withdrawn from patients taking lipid-lowering agents. Such patients should be monitored very closely or, when appropriate, recombinant human thyroid-stimulating hormone injections should be used rather than levothyroxine withdrawal in this setting.