ICD-10 Code E70.5 – Disorders of tryptophan metabolism (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E70.5 – Disorders of tryptophan metabolism
What it is
E70.5 identifies inherited disorders that impair the body’s normal processing of tryptophan, an essential amino acid. These conditions can affect the production of downstream metabolites and may lead to metabolic abnormalities.
Clinical signs
Clinical features vary; refer to documentation. Patients may have findings related to abnormal tryptophan metabolism, such as neurologic, gastrointestinal, or nutritional concerns, depending on the specific disorder.
When to use this code
Use E70.5 when the provider documents a disorder of tryptophan metabolism or a specific inherited condition in this category. Code it when the diagnosis is established or clearly supported in the record. If the chart names a more specific metabolic disorder, code that diagnosis instead.
Do not use for
Do not use E70.5 for nonspecific amino acid abnormalities without documentation of tryptophan involvement. Check documentation if the record only mentions suspected metabolic disease or a different inherited metabolic disorder.
Coding tip
Confirm the exact metabolic diagnosis in the note; if the provider names a specific syndrome, assign the more specific code when available.