ABSTRACT In Cuba, newborn screening (NBS) for cystic fibrosis (CF) was introduced in January 2019. The results from the first three years of the CF NBS program are presented. An IRT/IRT protocol was followed using a cut-off value of 50 ng/mL. In this period 281,717 neonates were screened, 2,197 samples had increased IRT values, and a second sample was necessary (recall rate=0.78%). In 686 (0.24%) neonates, IRT was still elevated, and they were referred for clinical evaluation. Twenty-one children were confirmed by sweat test and molecular biology. Eighteen newborns presented variant F508del. A false negative case was reported. Demographic data of 32,764 neonates were collected. The average age of sampling was six days with results available at 11 days of life, but 1.7% of the samples were collected 20 days after birth. The mean IRT value was 12.7±11.7 ng/mL (ranging 0-283 ng/mL) with a calculated 98.5 percentile value of 42.4 ng/mL. On average, the samples were processed five days after collection and two days after they were received at the laboratory. Although CF NBS program in Cuba is just beginning, it can be predicted that CF will be one of the most frequent inherited-metabolic diseases in the Cuban population.

Congenital hypothyroidism (CH) is one of the most common preventable causes of mental retardation. Newborn screening and thyroid therapy started within 2 weeks of age can normalize the cognitive and motor impairment caused by lack of thyroid hormone during the early postnatal phase of brain development. The availability of assays to determine thyroxin (T4) and thyroid stimulating hormone has allowed the establishment of newborn screening programs for CH. The Immunoassay Center (Cuba) developed the T4 Neonatal UMELISA(r) to determine neonatal T4 levels in dried blood on filter paper using 5 mm discs of samples, standards and controls. The number of diseases which can be diagnosed in Neonatal Screening Programs has increased, so it is necessary to make the maximum use of blood samples collected on filter paper. This work shows the standardization of the T4 Neonatal UMELISA(r) modified in order to use 3 mm discs. The assay was completed in 3 1/2 hours, with a measuring range of 25-400 nmol/L. The intra- and inter-assay coefficients of variation (CV) were 6-10 % and 7-12 % respectively, depending on the T4 concentrations. The recovery ranged from 91.8-115.1 %. The modified assay showed high Pearson correlation (r = 0.877) and concordance correlation (?c = 0.867) with the T4 Neonatal UMELISA(r). The performed modifications do not affect the sensitivity, precision and accuracy of the assay, permitting a more rational use of newborn blood samples and the possibility to increase the number of diseases included in the newborn screening programs.

El hipotiroidismo congénito (HC) es una de las causas más frecuentes de retraso mental prevenible en la infancia. La pesquisa neonatal (PN), su diagnóstico y tratamiento, podrían normalizar la discapacidad cognitiva y motora por la falta de hormonas tiroideas durante la etapa temprana de desarrollo del cerebro. Los ensayos para determinar la tiroxina total (T4) y la hormona estimulante del tiroides han permitido establecer programas de PN del HC. El Centro de Inmunoensayo, de La Habana, desarrolló el ensayo inmunoenzimático competitivo UMELISA T4 Neonatal(r) para determinar los niveles de T4 en neonatos, utilizando discos de 5 mm de muestras, calibradores y controles de sangre seca sobre papel de filtro. Las enfermedades que se pueden diagnosticar mediante esos programas han aumentado, por lo que se deben optimizar los estudios con las muestras de sangre de recién nacidos tomadas en papel de filtro. Este trabajo consistió en la estandarización de un UMELISA T4 Neonatal(r) modificado para emplear discos de 3 mm. El ensayo dura 3 1/2 h, y el análisis abarca entre 25 y 400 nmol/L. Los coeficientes de variación intra e interensayo estuvieron en los rangos 6-10 % y 7-12 %, respectivamente. La recuperación fue de 91.8 y 115.1 %. La correlación de Pearson fue elevada (r = 0.877) y hubo concordancia de la correlación (?c = 0. 867) con el UMELISA T4 Neonatal.

Quality of the sample and phenylalanine and 17-hydroxyprogesterone levels in neonatal screening. In the programs for neonatal screening many different analytes are quantified from dried blood on filter paper cards. Several factors affect the quality of the samples invalidating their employment in the laboratory: inadequate collection procedures, quality of the filter paper, the drying, storage and transportation under extreme environmental conditions. This article aims to show how the quality of the sample collection influences the phenylalanine (Phe) and 17-hydroxyprogesterone (17-OHP) levels. As such, samples of newborns on filter paper from Ramon Gonzalez Coro Hospital were collected and analyzed.The blood spots from a sample were classified according to their appearance, satisfactory spot (MV) or unsatisfactory spot (MNV). Phe and 17OHP levels were determinated by UMTEST PKU and UMELISA 17OH Progesterone NEONATAL, respectively. 19.5% of 3043 newborns samples exhibited unsatisfactory spots. Concordance correlations studies between MV y MNV showed the precision and accuracy were affected by quality of the samples. False positive and negative values (with concerning control sample) were detected from samples with MNV. The correct application of collection procedures for samples is essential in obtaining reliable results in screening neonatal laboratories.

En los programas de pesquisa neonatal, diferentes analitos son cuantificados en muestras de sangre de recién nacidos, impregnadas sobre papel de filtro. Varios factores pueden afectar la calidad de las muestras e invalidar su empleo en el laboratorio: procedimientos inadecuados en la colecta, calidad del papel de filtro y procesos de secado, almacenamiento y transportación bajo condiciones ambientales extremas. Para documentar la influencia de la calidad de la muestra sobre los niveles de fenilalanina y 17-hidroxiprogesterona en manchas de sangre seca sobre papel de filtro, se analizaron muestras de recién nacidos provenientes del Hospital Materno-Infantil "Ramón González Coro". Las manchas provenientes de una misma muestra se clasificaron según su apariencia, en válidas o "no válidas". Los niveles de fenilalanina y 17- hidroxiprogesterona se determinaron mediante el empleo de UMTEST PKU y UMELISA 17OH Progesterona NEONATAL, respectivamente. De 3 043 muestras analizadas, el 19.5% presentó manchas con características "no válidas". Los estudios de concordancia de la correlación entre ellas, mostraron que la calidad de la muestra afectó la precisión y la exactitud de los niveles de fenilalanina y 17-hidroxiprogesterona en sangre seca. En las muestras con características "no válidas" fueron detectados resultados discordantes, con valores falsos positivos o negativos con respecto a la muestra control. La aplicación correcta de los procedimientos de colecta de las muestras de pesquisa neonatal es esencial para la obtención de resultados confiables en los laboratorios.