ICD-10 Code E70.40 – Disorders of histidine metabolism, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E70.40 – Disorders of histidine metabolism, unspecified
What it is
E70.40 identifies a disorder affecting histidine metabolism, but the specific inherited or acquired defect is not documented. Use it when records confirm a histidine-related metabolic disorder without further detail.
Clinical signs
Clinical features vary; refer to documentation. Reports may mention developmental delay, neurologic findings, or abnormal amino acid testing, but you should not assume a specific syndrome without clear provider evidence.
When to use this code
Use this code when the clinician documents a histidine metabolism disorder and does not specify the exact type. It is also appropriate when the chart notes an unspecified amino acid metabolism disorder limited to histidine. If the record names a more specific diagnosis, code that condition instead.
Do not use for
Do not use E70.40 for a confirmed, named histidine disorder when a more specific code is available. Do not assign it for general nutritional problems or abnormal labs alone; check documentation.
Coding tip
Look for the exact metabolic diagnosis in the assessment, not just test results, before selecting this unspecified code.