Methylmalonic Acidemia (ICD-10-CM Code: E71.120)

Name of the Condition

• Methylmalonic acidemia.

Summary

Methylmalonic acidemia is an inherited metabolic disorder that impairs the body's ability to process certain amino acids and fatty acids. This disruption leads to the accumulation of methylmalonic acid and other toxic metabolites, which can cause neurological, hematologic, and systemic complications if not managed.

Causes

Genetic mutations affecting enzymes or cofactors involved in the catabolism of methylmalonic acid. These disorders are typically inherited in an autosomal recessive pattern, though specific inheritance patterns may vary by subtype.

Risk Factors

• Family history of metabolic disorders.
• Consanguinity (parents who are closely related).
• Certain ethnic or geographic populations with higher carrier rates for specific mutations.

Symptoms

• Developmental delay or regression.
• Lethargy or poor feeding in infants.
• Vomiting or poor weight gain.
• Neurological symptoms, such as seizures or abnormal muscle tone.
• Metabolic crises, including ketoacidosis or hyperammonemia, in severe cases.

Diagnosis

Diagnosis involves biochemical testing to measure organic acid levels in urine or blood, often supplemented by genetic testing to identify specific mutations. Newborn screening may detect some forms of this disorder.

Treatment Options

Treatment typically includes dietary modifications to limit protein intake, supplementation with specific vitamins or cofactors, and in some cases, liver or combined liver-kidney transplantation. Close monitoring by a metabolic specialist is essential.

Prognosis and Follow-Up

Prognosis varies depending on the severity of the condition and the timeliness of intervention. Long-term follow-up with a metabolic specialist is necessary to manage complications and adjust treatment as needed.

Complications

• Neurological damage, including intellectual disability or movement disorders.
• Kidney failure or other organ dysfunction.
• Recurrent metabolic crises, which can be life-threatening.

Lifestyle & Prevention

• Adherence to a specialized diet prescribed by a metabolic dietitian.
• Avoidance of triggers that may precipitate metabolic crises, such as prolonged fasting or illness.
• Regular monitoring of metabolic status through blood and urine tests.

When to Seek Professional Help

Seek immediate medical attention if symptoms of metabolic crisis occur, such as severe lethargy, vomiting, or difficulty breathing. Routine follow-up with a metabolic specialist is essential for ongoing management.

Tips for Medical Coders

Document the specific subtype of methylmalonic acidemia when available, as this may impact coding and clinical management. Ensure documentation supports the diagnosis and any associated complications or treatments provided.