Classical phenylketonuria

This code represents the most common and severe form of phenylketonuria (PKU), an inherited metabolic disorder characterized by the body's inability to properly metabolize phenylalanine, an amino acid. Without treatment, high levels of phenylalanine can accumulate in the blood and brain, leading to intellectual disability, seizures, and other neurological problems.

This code is used for patients diagnosed with classical PKU, typically identified through newborn screening programs. Documentation should clearly state the diagnosis of classical PKU, often supported by elevated phenylalanine levels and genetic testing results confirming mutations in the PAH gene.

• Differentiate from other forms of hyperphenylalaninemia; this code is specific to the classical type.
• Ensure documentation specifies "classical" PKU to support the use of this precise code.
• Consider sequencing with codes for any associated intellectual disabilities or neurological manifestations if present.