Comparison of two urinary purine spectrum detection methods and their application in phenylketonuria

XIE Xun-jie; JIANG Jian-hui; ZENG We-hong

doi:10.13820/j.cnki.gdyx.20231157

Abstract：Objective To evaluate two pre-processing methods,iodine(I2)oxidation method and manganese dioxide(MnO2)oxidation method,in urinary purine spectrum detection to improve the accuracy of phenylketonuria(PKU)diagnosis and classification.Methods A total of 65 urine samples were processed using I2 oxidation and MnO2 oxidation methods.Quantitative analysis of the content of neopterin(N)and biopterin(B)in urine,comparison of the two methods in terms of the lowest detection limit,precision,recovery rate,and analysis of the diagnostic compliance rate in PKU were conducted.Results The diagnostic compliance rates for PKU,tetrahydrobiopterin deficiency(BH4D),and normal children urine samples were all 100％for both I2 oxidation and MnO2 oxidation methods.The concentrations of N and B detected by the I2 oxidation method were higher than those by the MnO2 oxidation method,with statistical signifi-cance(P＜0.05).The detection limits for both N[I2 oxidation method:(0.000 63±0.000 27)μg/L;MnO2 oxidation method:(0.000 76±0.000 32)μg/L]and B[I2 oxidation method:(0.000 84±0.000 35)μg/L;MnO2 oxidation method:(0.000 81±0.000 33)μg/L]were better for the I2 oxidation method.Both methods showed good within-batch precision(CV)for N(I2 oxidation method and MnO2 oxidation method:2.54％,3.51％)and B(I2 oxidation method and MnO2 oxidation method:2.43％,3.26％).The between-batch CV was better for the I2 oxidation method(N:2.26％,6.25％;B:2.75％,7.32％)compared to the MnO2 oxidation method.In the low concentration standard recov-ery test,the N recovery rate for the I2 oxidation method was poor(N:128.19％,85.7％;B:93.49％,87.55％),while in the middle and high concentration standard recovery test,the recovery rates for N and B were good for both meth-ods(N:109.90％,99.59％;B:97.57％,103.29％for the I2 oxidation method;N:94.71％,98.41％;B:95.43％,100.5％for the MnO2 oxidation method).Both methods exhibited good linearity within the range of 0.01～2.00 μg/L.Conclusion Both the I2 oxidation method and MnO2 oxidation method can effectively differentiate PKU and BH4D and meet clinical testing needs,with the I2 oxidation method performing better.