<prompt> Keshans cardiomyopathy due to deficiency of:ChromiumSeleniumMagnesiumCopper  <response>: Selenium Selenium as selenocysteine is an essential component of the enzyme glutathione peroxidase Selenium containing enzyme 5-deiodinase conves thyroxine T4 to triiodothyronine in the thyroid gland. Thioredoxin reductase, involved in purine nucleotide metabolism Sources- seafood and meat, nuts Deficiency - Keshans disease Toxicity - Selenium toxicity lead to Selenosis 