Thyroid hormones regulate our body’s metabolism and influence virtually every organ system in the body. hypothyroidism may be associated with a wide range of muscle disturbances varying from myalgia to a true myopathy. biochemical tests such as Creatine Kinase (CK) or Creatine phosphokinase (CPK) and Lactate Dehydrogenase (LDH) can be used. Of these, CK is the most sensitive indicator and measure of muscle damage and LDH is a general indicator of tissue damage. studied the serum creatine kinase in thyroid disorders and reported that there is an inverse relation in the serum levels of T3 and creatine kinase (CK) in thyroid disease