高苯丙氨酸血症患儿苯丙氨酸负荷试验后苯丙氨酸和酪氨酸浓度变化

目的了解苯丙氨酸负荷试验对高苯丙氨酸血症HPA患儿血苯丙氨酸Phe和酪氨酸Tyr浓度及其比值Phe/Tyr的影响。方法HPA组30例,非HPA儿童(对照组)33例。所有儿童均空腹口服Phe100mg/kg,分别于服Phe前0h、服Phe后1h、2h、3h、4h采手指血,滴于滤纸片上,取直径3mm干血滤纸片,经含Phe和Tyr同位素内标的甲醇萃取,盐酸正丁醇衍生,进行串联质谱分析,测定Phe、Tyr浓度和Phe/Tyr值。结果血Phe浓度HPA组于服Phe后2h最高,服Phe后4h仍维持在较高水平,对照组于服Phe后1h值最高,服Phe后4h下降至接近正常浓度,两组比较各时间段差异均有显著性(P<0.001)。Tyr浓度HPA组各时间段差异无显著性,对照组于服Phe后逐渐升高,各时间段差异有显著性P<0.05,于服Phe后2h、3h时高于HPA组,差异有显著性(P<0.05)。Phe/Tyr值HPA组各时间段均高于对照组,差异非常显著(P<0.001)。结论HPA患儿Phe代谢速度下降,测定血Phe浓度结合Phe/Tyr值有助于HPA诊断。

Changes of phenylalanine and tyrosine levels after phenylalanine loading test in children with hyperphenylalanemia

Objective To observe the influence of phenylalanine (Phe) loading test on the blood levels of Phe,tyrosine (Tyr) and Phe/Tyr in children with hyperphenylalanemia (HPA).Methods The samples of the filter papers with blood obtained from fingers of 30 children with HPA(HPA group) and 33 healthy children(control group) were collected at 0(baseline),1,2,3,and 4 hours after administration of Phe(100 mg/kg) orally.Blood filter papers were extracted by methanol solution with stable isotope labeled internal standards and derived with butanolic- HCI.Levels of Phe,Tyr and Phe/Tyr in the samples were analyzed by tandem mass spectrometry.Results The post- load Phe level in children with HPA kept higher at all periods of time,and its peak was at 2 hours after administration.The post- load Phe level in control group reached its peak at 1 hour,and then decreased.There was a significant difference between HPA group and control group(P<0.001).No significant difference in the Tyr level was observed at all periods of time in HPA group,while in control group the post- load Tyr level at each period of time increased significantly compared to 0 hour after administration(P<0.05).In particular,post- load Tyr level at 2 and 3 hours in control group were higher than those in HPA group(P<0.05).Furthermore,the Phe/Tyr levels in HPA group were higher than those in control group at all periods of time(P<0.001).Conclusions The metabolic velocity of Phe is slow in HPA children.The detection of Phe and Phe/Tyr will be helpful for the diagnosis of HPA.