Analysis of urine metabolites levels in children with hyperphenylalaninemia

Objective To explore the relationship between blood phenylalanine(Phe) and urine metabolites by detection of blood Phe,urinary phenylpyruvate,phenylacetate and phenyllactate levels in children with hyperphenylalaninemia(HPA) Methods Fifty-five children with hyperphenylalaninemia were selected,the level of Phe in the dried blood spot was tested by tandem mass spectrometry and urine levels of phenylpyruvate,phenylacetate and phenyllactate pretreated using urease were tested by gas chromatography mass spectrometry.Results Blood level of Phe and urine levels of phenylpyruvate,phenylacetate and phenyllactate showed significant positive correlations(r=0.61-0.84,P0.01).For both blood level of Phe 360 mmol/ L and 360-1 200 mmol/L groups,rank tests showed significant differences among urine phenylpyruvate,phenylacetate and phenyllactate(P0.01);The normal number of children with urine levels of phenylpyruvate,phenylacetate and phenyllactate showed 14 cases(70%),2 cases(5.71%),both was significantly different(P0.01).Conclusions The variation of urinary phenylpyruvate,phenylacetate and phenyllactate is correlated to blood Phe in children with HPA.However,it will lead to false negative result if the diagnosis made by detecting phenylpyruvate,phenylacetate and phenyllactate only.