Isovaleric Acidemia. Chronic intermittent form.
Incidence
Is as common as the neonatal form (50%). AR disease. It is not a rare disease. More than 60 cases reported up to 1989 (1/2 neonatal, 1/2 chronic intermittent form).
Clinical Characteristics
During the first year of life intermittent ketoacidotic comas, with severe hyperammonemia, "sweaty feet" smell, pancytopenia, low calcium and ketoacidosis. Also hyperglycemia and alopecia, mild MR & developmental delay will eventually appear. Patients have a natural aversion for protein-rich foods. The reccurrent attacks tend to decrease with age.
Precipitants
Infections, vomiting, diarrhea and fasting.
Provocation Tests
Leucine loading (25 mg/kg, 50 mg/kg or 100 mg/kg) with or without glycine (150 or 250 mg/kg) or with benzoate (200 mg/kg) or with L-carnitine (200 mg/kg) leads to increased excretion of metabolites. May use when tandem MS unavailable
Diagnostic Procedures
EB-F, OB-W