[Study of blood amino acids during a phenylalanine loading test]

A study of serum amino-acids during a L-phenylalanine loading test was performed in controls, heterozygotes and phenylketonuric patients with and without restricted diet. Abnormalities in plasma-amino acids were found in phenylketonuric patients at time zero with a fall of the level of some amino-acids (except for phenylalanine) when compared with the levels found in controls. These results are statistically valid only for threonine and proline. These abnormalities of the plasma amino-acids disappeared when patients were treated by a restricted diet. At the end of a loading test, there was no statistically valid changes of the blood amino-acids in controls, heterozygotes nor in patients with a restricted diet. There was no enhancement of the abnormalities in phenylketonuria.