Newborn screening standardization

In many localities, newborn screening has become standard for this disorder, which in the general population has an approximate incidence of 1/250,000 live births. Carrier detection is possible, either by measurement of enzymatic activity in cultured fibroblasts or by study of restriction endonuclease fragments of DNA. Antenatal testing is also available. 

Dried blood spots are prepared from native blood on standardized filter paper (Whatman 903, Whatman). The paper has to be fully soaked with blood and dried at room temperature. Blood has to be applied from one side only, to ensure even distribution throughout the filter paper. Do not use any plastic wrapping before the paper is completely dry. For further details, consult the guidelines from your closest newborn screening facility or metabolic laboratory processing dried blood specimens. 

In some applications like newborn screening and filter paper blood spots, the internal standard that is labeled cannot be mixed with blood. It can only be present in the extraction solvents. Therefore, only the extracted metabolites can be quantitatively measured. I have denoted a term called pseudo-isotope dilution to account for the differences between traditional isotope dilution and the technique commonly used in newborn screening by MS/MS. A special analysis is capable using this technique, however, in terms of an extraction efficiency experiment. With isotope-labeled standards you can perform an experiment whereby a traditional isotope-dilution technique (internal standard added to liquid blood and spotted) is compared to pseudo-isotope dilution techniques (internal standard is added to the extraction matrix). The ratio of the results of these two analysis (pseudo/traditional) is the extraction efficiency. 

Hannon, W.H. (2007) Blood Collection on Filter Raper for Newborn Screening Rrograms Approved Standard— Fifth Edition. NCCLS Document LA4-A5, p. 27. 

Similarly, a direct multiplex assay of lysosomal enzymes in dried blood spots has been developed for newborn screening [18]. This approach is based on the incubation of dried blood spots at 37°C overnight with the appropriate substrates and stable isotopically labeled internal standards. If the enzyme was fully active, substrate was converted completely to the corresponding product which was quantified based on its relationship to the known concentration of the internal standard. Importantly, samples without dried blood spots ( blank ) have to be used to adjust for background noise. Corresponding enzyme activities were calculated based on the assumption that 10 xl of extraction solution contained 0.98 (xl of blood [18]. 

Unfortunately, Perkin-Elmer whcTiras produced this instrument has built the instrument for the purpose of measuring bilirubin in amniotic fluid. As a result, the instriment does not read above a level of approximately 2 mg/100 ml. Therefore, it is necessary to dilute the serum from newborns in order to be read in this instrument. However, if one standardizes by making a 1 to 5 dilution of all newborn serum, one can use this method for screening purposes. One looks forward to the further development of this instrument so that readings can be made over a wide range. 

Lipid Screening. The problems of lipid analysis in the newborn is difficult because of the fact that most methods for analysis for lipids require substantial amounts of serum, yet a total lipid determination is very important in various types of disease. This problem can be solved by thin-layer chromatography (59). Figure 38 shows a typical pattern obtained when an extract 7rom 10 microliters of serum is subjected to thin-layer chromatography. If these specimens are scanned, and an internal standard is run, one can obtain a rough approximation of the distribution of the various lipids in the serum. This is shown in Figure 39, in which a normal specimen is run in an adult. 

Donor placenta is obtained after elective cesarean, and with informed maternal consent. Maternal donors are screened at deUvery usually by physical exam, reviewing medical history and standard questionnaire to assess the possibility of transmittable diseases. Suitability for transplant is determined by the absence of any infectious, malignant, neurological and autoimmune diseases and other exposures or social habits deemed improper to transplantation. Donors are screened for transmittable diseases such as HIV, HCV, hepatitis B, hepatitis C, and syphilis. These screening takes place predonation and bmonths after donation. No harm to either the newborn or maternal donor is encountered during the procurement process. - ... 

In order to use your procedure, that is the TSH values obtained from the screening of congenital hypothyroidism, how important is it to standardize the conditions For instance, does the variability of iodine in human colostrum play a role Is there a difference in relation to the time of initiation of breastfeeding Is it different if the newborn gets its iodine supplement from maternal milk or from formula milk How do you control for the differences in the iodine content of formula milk, since we saw during this meeting that 100 % differences may be found between various types of formula milk. 

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