PATIENT FACT SHEET Metabolic Myopathies

Metabolic myopathies are rare, genetic disorders that muscle tissue gets damaged and substances from inside cause muscle problems. “Metabolic” refers to chemical the muscle cells enter the bloodstream). reactions that provide necessary energy and nutrients for To work properly, muscles need a chemical called healthy muscle growth. adenosine triphosphate (ATP). Cells make ATP from Metabolic myopathies are inherited and tend to run in sugars and fats on certain pathways in chemical CONDITION families. They can occur at any age. Genetic defects reactions driven by enzymes. Lack of certain enzymes DESCRIPTION interfere with the processes in muscle that generate causes metabolic myopathies, which are named energy. Muscle cells cannot work properly. Some according to the pathways affected. myopathies can cause rhabdomyolysis (a process when

Symptoms of metabolic myopathies include muscle Rhabdomyolysis, or the death of muscle cells, occurs weakness, tiring after exercise or activity, muscle pain when cells do not have enough ATP. Low-grade after any physical effort, and swollen or tender muscles. rhabdomyolysis may cause constant weakness. Some people with metabolic myopathies never have A rheumatologist can diagnose metabolic myopathies with symptoms. Other pathways in their body make the ATP a muscle tissue biopsy or genetic testing. With a biopsy, a necessary for muscles to work when one pathway does needle is used to remove a small sample of tissue. not work. When the body needs to make more energy SIGNS/ from that pathway, an ATP deficit can develop and cause SYMPTOMS symptoms. If cells are moderately low in ATP, signs are fatigue or exercise intolerance.

Treatments vary according to the patient’s The goal of treatment is to control symptoms particular myopathy. Treatments include and minimize progression of muscle weakness. changes in physical activity and diet, aerobic Physical and occupational therapy are often and anaerobic (resistance) exercise training, important in the management of metabolic and the use of various vitamins and supplements. myopathies. COMMON TREATMENTS

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Updated March 2019 by Christopher Mecoli, MD, and reviewed by the American College of Rheumatology © 2019 American College of Rheumatology Committee on Communications and Marketing. This information is provided for general education only. Individuals should consult a qualified health care provider for professional medical advice, diagnosis and treatment of a medical or health condition.