ICD-10 Code E71.31 – Disorders of fatty-acid oxidation (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E71.31 – Disorders of fatty-acid oxidation
What it is
E71.31 identifies inherited disorders that impair the body’s ability to break down fatty acids for energy. These conditions can cause energy shortage during fasting, illness, or increased physical stress.
Clinical signs
Clinical features vary; refer to documentation. Common findings include recurrent hypoglycemia, lethargy, vomiting, muscle weakness, and episodes triggered by fasting or infection.
When to use this code
Use E71.31 when the record clearly documents a fatty-acid oxidation disorder, such as a confirmed inborn error of metabolism or a specified FAO defect. Apply it for encounters focused on the disorder itself, including evaluation, surveillance, or management of known disease. If the note only suggests a possible metabolic problem, check documentation before coding.
Do not use for
Do not use this code for nonspecific hypoglycemia, malnutrition, or other metabolic disorders without documentation of fatty-acid oxidation impairment. Check documentation if the diagnosis is suspected but not confirmed.
Coding tip
Code the documented FAO disorder as stated, and verify whether the provider identifies a specific subtype or only the broader category.