Experience with the 3-phenylpropionic acid loading test for diagnosis of medium-chain acyl-CoA dehydrogenase deficiency (MCADD).

MCADD is an autosomal recessively transmitted inborn error of C6-C12-carboxylic acid metabolism, causing episodically attacks of life threatening hypoketotic hypoglycemia or Reye-syndrome-like disease. Diagnosis is made best by investigating urinary organic acids before and after a load with 3-phenylpropionate. From 1986 until now 29 patients with MCADD were detected in Freiburg by selective screening for inherited metabolic disorders; 27 of them were confirmed by challenging with 3-phenylpropionic acid. The remaining two patients were not available for further investigations. The 3-phenylpropionate loading test is recommended in patients suffering from recurrent attacks of hypoketotic hypoglycemia and in families, where sudden infant death syndrome (SIDS) or near miss SIDS has occurred.