Disturbances of histidine metabolism

This code signifies an inherited metabolic disorder affecting the breakdown of the amino acid histidine. It typically results from a deficiency in the enzyme histidase, leading to an accumulation of histidine and its byproducts in the blood and urine. While often benign, some individuals may present with developmental delays or speech difficulties.

Apply this code when documentation confirms a diagnosis of histidinemia, an inborn error of metabolism characterized by elevated histidine levels. This diagnosis is typically established through newborn screening or subsequent biochemical testing (e.g., plasma amino acid analysis, urine organic acids).

• Ensure documentation specifies "histidinemia" or "histidine metabolism disorder" rather than a general amino acidopathy.
• Consider any associated neurological or developmental manifestations, which may require additional coding.
• This is a legacy ICD-9-CM code; for current coding, refer to the equivalent ICD-10-CM code.