Screening for genetic metabolic disorders is a method of screening for phenylketonuria and heel prick test congenital hypothyroidism based on medical resources, public demand, morbidity and other conditions.
Screening procedures include blood smear collection, laboratory testing, identification of positive cases, and treatment.
1. Blood smear collection and transport The normal time for blood collection is 72 hours after birth and within 7 days, with full use of breastfeeding;
For those who have not collected blood (premature babies, low weight babies, newborns under treatment for related diseases, and those who are discharged from the hospital in advance, etc.), the time of blood collection is usually no more than 20 days after birth.
The main site of blood collection is the medial or lateral heel of the newborn, and at least three blood spots should be collected from the filter paper sheet, which should be dried naturally and then made into a filter paper dry blood sheet.
They should be placed in a sealed bag and stored airtight in a refrigerator at 2~8℃, and sent to the neonatal laboratory for safe testing due to genetic metabolic disease research no later than 5 working days.
2. Screening Phenylalanine can be used as a screening indicator for phenylketonuria. Phenylalanine ion concentration for positive cut-off value according to the national laboratory and reagent kit requirements, generally greater than 2mg/dl is screening positive.
The screening methods are fluorescence data analysis, quantitative enzymatic method, bacterial inhibition method and tandem mass spectrometry.
Thyrotropin (TSH) is used as a screening indicator for congenital hypothyroidism, and the positive cut-off value of TSH concentration depends on the laboratory and the reagent kit, with screening positive values generally greater than 10-20 IU/ml.
Screening methods are time-resolved immunofluorescence analysis, enzyme immunofluorescence analysis and enzyme-linked ELISA.