What does the newborn screening test?

Babies are very important to parents. Parents pay attention to their babies all the time. I believe many people know that after a newborn is born, the hospital will screen the baby for multiple diseases. Many people don’t know what diseases to screen for in newborn babies. When this kind of screening occurs, many parents will worry about what kind of diseases their baby will be diagnosed with. So what aspects of the baby will be checked for newborn multi-disease screening?

Newborn disease screening refers to the group screening of certain serious congenital metabolic diseases and endocrine diseases through blood tests, so that children can be diagnosed and treated early, avoiding growth, intellectual development disorders or even death due to damage to the brain, liver, kidneys, etc. The coverage rate of newborn disease screening in developed countries such as Europe, the United States, and Japan is nearly 100%. Newborn disease screening in my country began in 1981, and the current coverage rate is close to 50%. In 2004, the former Ministry of Health issued the "Technical Specifications for Newborn Disease Screening" document. Various provinces and cities have also formulated corresponding screening routines and implementation documents based on local characteristics, making newborn disease screening more standardized. Newborn disease screening is a systematic project that integrates organizational management, experimental technology, clinical diagnosis and treatment, and publicity and education. It should follow the principles of autonomy, beneficialness, harmlessness, and fairness. The development of screening programs needs to consider key issues such as the incidence of the disease, the feasibility and promotion of screening technology, and whether the screened disease can be treated.

Newborn screening

1. Subjects: All live-born newborns within 72 hours of birth (with at least 6 to 8 breastfeedings).

2. The types of diseases screened vary by race, country, and region, and are also related to each country's social, scientific and technological development, economic level, and the severity of the disease. Internationally recognized conditions for screening diseases include:

①There is a certain incidence rate;

② Lack of special symptoms in the early stage;

③ Serious harm;

④It can be treated;

⑤ There are reliable screening methods suitable for large-scale implementation. A conference held in Europe in 1974 recommended 20 diseases for screening, including phenylketonuria (PKU), maple syrup urine disease, histidinemia, galactosemia, etc. In 2006, the American College of Medical Genetics Newborn Screening Expert Group evaluated the severity of 84 existing congenital diseases in newborns. Based on screening technology, diagnosis, differential diagnosis and treatment, they were divided into the first category of 29 primary screening diseases, the second category of 25 secondary screening diseases and diseases that are difficult to screen at this stage. At present, the diseases screened in my country are still mainly phenylketonuria (PKU) and congenital hypothyroidism (CH). Some regions choose to screen for diseases such as glucose-6-phosphate dehydrogenase (G6PD) deficiency based on the incidence of the disease, or begin to use tandem mass spectrometry technology to conduct newborn screening for other rare genetic metabolic diseases such as amino acids, organic acids, and fatty acids.

3. Methods

(1) Blood collection time: Blood should be collected within 72 hours after the baby is born and has been breastfed at least 6 to 8 times.

(2) Blood collection filter paper

Blood collection filter paper must be consistent with standard filter paper, which is a special pure cotton high-quality filter paper with fairly uniform texture, thickness, water absorption, and water permeability. The filter paper used by most neonatal disease screening centers is the internationally recognized Schleicher &

Schuell 903 special filter paper not only ensures the quality of screening, but also has comparability with international screening materials.

(3) Blood collection site and method

Choose the inside or outside of the baby's heel. The method is: massage or hot compress the baby's heel to make it congested, then disinfect it with alcohol and puncture it with a disposable blood collection needle, about 2 to 4 mm deep, discard the first drop of blood and drop the squeezed blood on a specific filter paper to allow it to fully penetrate to the back of the filter paper. It is required to collect 3 blood spots from each infant, and the diameter of each blood spot should be ≥10 mm.

(4) Storage and delivery of specimens: The blood filter paper should be dried in the shade at room temperature and delivered to the screening center within the specified time, or temporarily placed in a paper bag and stored in a refrigerator at 2-10℃.

(5) Requirements for filling out the blood collection card: All items on the blood collection card should be filled out one by one without missing any items. The handwriting should be clear and the text should be standardized.

(6) Screening methods

With the development of current experimental diagnostic technology, most domestic screening laboratories have adopted fluorescence analysis (fully quantitative) for PKU screening. A very small number still use the traditional Guthrie bacterial inhibition method (semi-quantitative). Some also use high-performance liquid chromatography for PKU screening. CH screening includes enzyme-linked immunosorbent assay and enzyme immunofluorescence assay. In the past decade or so, developed countries have adopted tandem mass spectrometry technology to screen about 25 kinds of inherited metabolic defects, including amino acid, organic acid, and fatty acid metabolism disorders, greatly improving screening efficiency. Tandem mass spectrometry technology is the future development direction of neonatal disease screening.

(7) Screening result processing

To ensure the quality of testing, the testing will be carried out by dedicated personnel. For negative test results, the city and county management centers are generally not notified. For suspected positive cases, they will be re-examined. If they are still positive, they will be fed back to the city and county centers. The city and county centers must cooperate in the recall (or follow-up), re-examination and confirmation of positive cases.

(8) Case tracking: After the diagnosis, the child should be given long-term and correct drug treatment or diet control in time to ensure the social effect of newborn disease screening.