四氢生物喋呤负荷试验在高苯丙氨酸血症鉴别诊断中的临床应用

目的探讨四氢生物喋呤（BH4）负荷试验在高苯丙氨酸血症（HPA）鉴别诊断中的应用价值。方法自2005年5月到2007年4月，51例HPA患儿采用口服BH4（20mg／kg）负荷试验。对其中血苯丙氨酸（Phe）浓度小于600μmol／L患儿采用口服Phe—BH4联合负荷试验，结合尿喋呤分析、血红细胞二氢喋呤还原酶（DHPR）活性测定。结果（1）在BH4负荷试验中，不同类型HPA患儿的血Phe浓度表现出各不相同的改变。51例HPA患儿中，共鉴别出5例BH4缺乏症，10例BH4反应性苯丙氨酸羟化酶（PAH）缺乏症，36例BH4无反应性苯丙氨酸羟化酶（PAH）缺乏症。（2）在17例中度苯丙酮尿症（PKU）患儿中，9例（52．9％）为BH4反应性PAH缺乏症。结论BH4负荷试验在HPA早期鉴别诊断中十分重要，部分中度PKU对BH4有反应，可使用BH4替代治疗。

The clinical utility of the tetrahydrobiopterin loading test in differential diagnosis among hyperphenylalaninemia patients

Objective ： To emphasize early differential diagnosis in hyperphenyla - laninemia （HPA） patients by oral tetrahydrobiopterin （BH4） loading test. Methods： From May in 2005 to April in 2007, BH4 （20mg/mg） loading tests were carried out in 51 patients with HPA, and a combined phenylalanine （ Phe, 100mg/kg） and BH4 loading tests were performed in the patients whose basic phenylalanine blood concentrations were less than 600μmol/L. The urinary pterins and dihydropteridine reductase activity in dried blood spots were measured simultaneously. Results： （ 1 ） The characteristic curves of the blood levels were observed in 51 patients after BH4 loading tests. Of the total, 5 cases were diagnosed as BH4 deficiency, 10 cases as BH4 responsive PAH deficiency. （2） 9 （52.9%） of 17 moderate PKU patients as BH4 responsive PAH deficiency. Conclusion： The BH4 loading test plays a importairt role in early differential diagnosis from patients with HPA. Some patients with moderate PKU are responsive to BH4 and be treated with BH4.