ICD-10 Code G71.3 – Mitochondrial myopathy, not elsewhere classified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code G71.3 – Mitochondrial myopathy, not elsewhere classified
What it is
G71.3 identifies a mitochondrial myopathy, a muscle disorder caused by impaired mitochondrial function. Use it when the record documents a myopathy linked to mitochondria and no more specific subtype is named.
Clinical signs
Common findings include exercise intolerance, muscle weakness, and fatigue. Clinical features vary; refer to documentation for supporting neurologic, muscular, or multisystem involvement.
When to use this code
Use this code when the provider diagnoses mitochondrial myopathy without specifying another classified mitochondrial disorder. It is appropriate for confirmed or clearly documented suspected myopathic involvement tied to mitochondrial disease. If the note names a more specific mitochondrial syndrome, code that instead.
Do not use for
Do not use G71.3 for generalized weakness, fatigue alone, or an unspecified neuromuscular complaint. Check documentation if the record describes a different mitochondrial disorder or a non-mitochondrial muscle disease.
Coding tip
Query the provider when the chart says “mitochondrial disease” but does not clearly state myopathy.