A muscle biopsy ( a procedure involving the removal and examination of a piece of muscle tissue ) may be the primary test used to confirm the diagnosis. In some cases a DNA test from the blood may be sufficient.

  • A serum CPK (an enzyme found in muscle) may be elevated. CPK is a blood test that measures creatine phosphokinase (CPK), an enzyme found predominantly in the heart, brain, and skeletal muscle. When the total CPK level is substantially elevated, it usually indicates injury or stress to one or more of these areas.
  • An EMG (electromyography) may confirm that weakness is caused by destruction of muscle tissue rather than damage to nerves. Electromyography is a test that measures muscle response to nervous stimulation (electrical activity within muscle fibers).
  • An ECG (electrocardiography) to monitor changes in cardiac status.

Note: This question has been posed by one of the viewers of this site. You may also pose your question in the comments.