Optimization of Phenylalanine Cut-Off Value in Newborn Screening Based on Blood Sampling Time.

OBJECTIVE: The aim of this study was to optimize the cut-off value of phenylalanine (Phe) for phenylketonuria (PKU) screening in Xinjiang Uygur Autonomous Region based on the time of blood sampling. STUDY DESIGN: In this study, 110,806 neonates born in 91 obstetrics and gynecology hospitals of Xinjiang Uygur Autonomous Region between June 2017 and December 2019 were divided into two groups (i.e., groups 1 and 2) based on the sampling time. The concentration of Phe was determined using fluorimetric method. The optimization of the Phe cut-off value was conducted using the receiver operating characteristic curve from the treating set involving 80,354 neonates. Then, the diagnostic values of the optimized Phe cut-off value were evaluated using validation set involving 30,452 neonates, based on the comparison of sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV) obtained from conventional cut-off value. RESULTS: A range of cut-off values was used for preliminary Phe concentrations in the two groups to analyze the sensitivity, specificity, PPV, and NPV. The optimized cut-off value of Phe in group 1 was 2.0, while that in the group 2 was 2.21. A comparison was given to PPV, NPV, sensitivity, and specificity generated by the optimized cut-off value and the conventional cut-off value, which yielded similar sensitivity, specificity, and PPV, and less recalled number of samples. CONCLUSION: The optimization of cut-off value of Phe based on sampling time is feasible for PKU screening in Xinjiang Uygur Autonomous Region. In addition, the false positive rate was significantly reduced, which may save more efforts in sample recalling process. KEY POINTS: · The optimization of Phe cut-off value for Xinjiang Region.. · The optimized cut-off value reduced the recalling samples.. · Our cut-off value is feasible for PKU screening in Xinjiang..

[Correlation between obesity index and blood pressure in Kazak childhood from Yili, Xinjiang].

OBJECTIVE: To investigate the correlations between obesity index such as waist circumference, hip circumference, skin-fold thickness, body mass index, waist to hip ratio, waist to height ratio etc, and blood pressure among Kazak children living in Yili of Xinjiang. METHODS: In May-June 2009, 2438 Kazak children aged 7 to 14 at primary schools in Yili of Xinjiang, were investigated. Waist circumference, hip circumference, skin-fold thickness, systolic and diastolic blood pressure were measured to calculate the body mass index, waist to hip ratio and waist to height ratio. Analysis on the differences in age and gender, blood pressure (BP) between hypertensive or normal BP group under the standard set for children. SPSS 17.0 software was used for statistical analysis on its correlation. RESULTS: The total prevalence of hypertension was 5.7% in Kazak ethnic school-age children in Yili, with 4.4% in the boys and 7.0% in girls. Data from waist circumference, hip circumference, waist-height-ratio, waist-hip ratio, systolic and diastolic blood pressure showed gender and age differences (P = 0.000). Average systolic blood pressure was correlated to waist circumference, hip circumference, skin-fold thickness, body mass index and waist to hip ratio (P = 0.000), with hip circumference the most (man: r = 0.618, female: r = 0.655). The average diastolic blood pressure was correlated to waist circumference, hip circumference, skin-fold thickness, body mass index and waist to hip ratio (P = 0.000), with hip having the strongest relation (r = 0.489 for male and r = 0.548 for females). Significant differences were seen between Hypertension group and normal blood pressure group on waist circumference, hip circumference, skin-fold thickness, body mass index and waist-hip ratio (P < 0.05). CONCLUSION: In Yili of Xinjiang, the prevalence of hypertension was at the low level in Kazak ethnic school-aged children when comparing to data from national and foreign standards. Indicators related to obesity as waist circumference, hip circumference, body mass index and waist to hip ratio were positively correlated with blood pressure, with hip in particular.

[Blood pressure levels of 2438 Hasakh children in the Yili region of Xinjiang Province].

OBJECTIVE: To study blood pressure levels, the prevalence of hypertension and factors associated with the development of hypertension in Hasakh children in the Yili region of Xinjiang Province. METHODS: A total of 2438 Hasakh school children from the Yili region of Xinjiang Province were sampled by stratified random cluster sampling method between May and June 2009. Height, weight, waist circumference, hip circumference, skinfold thickness and blood pressure were measured. Body mass index (BMI) was calculated. RESULTS: Mean systolic blood pressure (SBP) and diastolic blood pressure (DBP) were 94±13 mm Hg and 60±9 mm Hg respectively in the 2438 children, and both averages were lower than in the Han children. Hypertension was noted in 138 children (5.66%). The prevalence of hypertension in girls (6.97%, 84/1206) was higher than in boys (4.38%, 54/1232) (P<0.05). The prevalence of hypertension and blood pressone were positively correlated with BMI, waist circumference, hip circumference, skinfold thickness circumference, gender and age. CONCLUSIONS: Average blood pressure levels in Hasakh children in the Yili region of Xinjiang Province are lower than in domestic age-matched Han children. The prevalence of hypertension in girls is higher than in boys. Obesity is highly correlated with the development of hypertension.