Other disorders of histidine metabolism

This code represents rare inherited metabolic disorders affecting the breakdown of histidine, an amino acid. These conditions result from deficiencies in specific enzymes involved in the histidine degradation pathway, leading to an accumulation of histidine or its metabolites in the body. While often benign, some forms can present with neurological or developmental symptoms.

Use this code when documentation specifies a diagnosis of a histidine metabolism disorder other than histidinemia (E70.40) or urocanic aciduria (E70.41). This typically includes conditions like histidase deficiency, which is the most common, or other less common enzymatic defects in the histidine pathway. Supporting documentation should clearly identify the specific enzyme deficiency or the precise "other" disorder.

• Do not use this code for unspecified disorders of histidine metabolism; use E70.40 for histidinemia.
• Ensure documentation specifies the exact "other" disorder; avoid using this code for vague or unconfirmed diagnoses.
• Consider genetic testing results or enzyme assay reports as supporting documentation for these rare conditions.