Testing for specific disorders may be needed: If findings suggest myasthenia gravis, an ice pack test and serologic testing (eg, acetylcholine receptor antibody levels, sometimes anti-muscle-specific tyrosine kinase antibodies) If findings suggest vasculitis, autoantibody testing If family history suggests a hereditary disorder, genetic testing If findings suggest polyneuropathy, other tests (see table Some Causes of Muscle Weakness) If myopathy is unexplained by drugs, metabolic, or endocrine disorders, possibly muscle biopsy Treatment of Weakness Causes of muscle weakness are treated.