ICD-10 Code E70.0 – Classical phenylketonuria (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code E70.0 – Classical phenylketonuria
What it is
Classical phenylketonuria is an inherited disorder of phenylalanine metabolism caused by phenylalanine hydroxylase deficiency. It leads to buildup of phenylalanine and requires lifelong dietary management.
Clinical signs
Clinical features vary; refer to documentation. Common findings include developmental delay, intellectual disability, seizures, behavioral problems, and a musty odor if untreated.
When to use this code
Use this code when the record specifically documents classical phenylketonuria, PKU, or phenylalanine hydroxylase deficiency. It also fits encounters for ongoing management, screening follow-up, or genetic counseling tied to confirmed disease. Check documentation when the note only says “hyperphenylalaninemia.”
Do not use for
Do not use it for newborn screening results without a confirmed diagnosis. Do not assign it for other amino acid disorders or nonspecific metabolic abnormalities unless the clinician documents classical PKU.
Coding tip
Code from the provider’s confirmed diagnosis, not from diet instructions alone.