title: [Determination of total phenylalanine and galactose from a sample of dry blood on paper filter: its application on neonatal screening].
abstract: Neonatal screening programs for metabolic disorders are recommended especially for phenylketonuria and congenital hypothyroidism. The present study was designed to adapt, develop and evaluate a SUMA method for total galactose (Gal) and phenylalanine (Phe) measurement on filter paper blood specimens. A single 5 mm disk with blood was deproteinized with methanol-acetone and eluted with distilled water. Ten microliters of the extract was transferred to one well of a ultramicroELISA plate, and the reaction solution was added to determine Phe level. The remaining extract was used for the GAL determinations. The method showed good linearity in a 0-50 mg/dl concentration range for Phe and 0-60 mg/dl for Gal. The detection limit was 0.14 mg/dl for Phe and 0.9 mg/dl for Gal. Reproducibility was assessed with filter paper blood specimens containing Gal and Phe at low, middle and high levels. Intraassay coefficients of variation were 10%, 7.5%, 6.22%, and 8.5%, 7%, 5%, respectively, whereas interassay coefficients of variation were 9.54%, 6%, 7% and 6%, 4.6%, 5.6%, respectively. In 1,000 samples from newborns, four samples of Phe and two samples of Gal showed a concentration below the threshold set for each assay. This method provides a rapid means to survey for a low incidence disease (i.e., galactosaemia: incidence, 1/30,000), in existing phenylketonuria analysis programs, where an incidence of 1/10,000), easily justifies the cost of mass screening.
authors.affiliation: Laboratorio de Pesquisaje Neonatal, Centro de Inmunoensayo, Ciudad de La Habana, Cuba.
authors.forename: Eneida
authors.initials: E
authors.lastname: Torres
authors.forename: Arlenys
authors.initials: A
authors.lastname: Baloy
authors.forename: Amarilys
authors.initials: A
authors.lastname: Frómeta
authors.forename: Lianny
authors.initials: L
authors.lastname: Fernández
mesh_terms: D001801:Blood Stains; D004797:Enzyme-Linked Immunosorbent Assay / Q000379:methods; D005690:Galactose / Q000097:blood*; D006801:Humans; D007231:Infant, Newborn; D015997:Neonatal Screening / Q000379:methods*; D010649:Phenylalanine / Q000097:blood*; D012016:Reference Values; D012680:Sensitivity and Specificity
chemical_list: D010649:Phenylalanine; D005690:Galactose