Histidinemia

This code represents histidinemia, an autosomal recessive metabolic disorder characterized by a deficiency in the enzyme histidase, leading to elevated levels of histidine in the blood and urine. It is typically a benign condition, though some individuals may exhibit speech delay, learning difficulties, or behavioral issues.

Assign this code when documentation confirms a diagnosis of histidinemia, often identified through newborn screening or subsequent diagnostic testing for elevated histidine. It is appropriate for patients with confirmed enzyme deficiency, regardless of the presence or absence of clinical symptoms.

• Ensure documentation specifies "histidinemia" and not a general amino acid metabolism disorder.
• Do not confuse with other inborn errors of metabolism affecting amino acids; this code is specific to histidine.
• Consider sequencing with codes for any associated neurological or developmental manifestations, if present and documented.