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This paper describes the development of an original micro-solid phase extraction device and its evaluation for the isolation of F2-isoprostanes (F2-IsoPs) from cord and maternal plasma samples. The unit is very simple and consists in a rotating disc (1.8 cm diameter) of oxidized buckypaper (BP), enwrapped in a polypropylene mesh pouch. Even if the selected F2-IsoPs have logP and pKa values that make them suitable candidates for their sorption on BP, several parameters were optimized to maximize recoveries: time of adsorption and desorption; stirring speed; volume, pH and ionic strength of the sample; type, volume, and fractions of the elution solvent; oxidation grade of BP. Among all, the last one was crucial in affecting extraction yields because of the analyte interactions with polar functionalities, introduced by a preliminary oxidative acid treatment. The investigation established the optimal oxidation time and highlighted the pros and cons of the acid activation step. All extracts were analyzed by means of liquid chromatography-tandem mass spectrometry (LC–MS/MS). Validation was performed according to the main FDA guidelines for bioanalytical methods. Depending on the spike level and analyte, recoveries ranged between 30 and 120% with precision and accuracy values lower than 20%. Quantitative analysis was accomplished by matrix-matched calibration curves whose determination coefficients were higher than 0.95. Lower limit of quantitation (LLOQ) spanned the range 2.45–6.77 μg L−1. The validated method was applied to the analysis of eight pairs of mother/child plasma samples, revealing the presence of 8-iso-15-keto-PGF2α and 8-iso-PGE2 at a concentration of about 10 μg L−1 in most cord plasma samples of preterm newborns.

Objectives: To determine the prevalence of congenital hypothyroidism in children with filter-paper blood-spot TSH (b-TSH) between 5 and 10 μIU/mL in the neonatal screening. Methods: This was a retrospective study including children screened from 2003 to 2010, with b-TSH levels between 5 and 10 μIU/mL, who were followed-up during the first two years of life when there was no serum TSH normalization. The diagnosis of congenital hypothyroidism was defined as serum TSH ≥10 μIU/mL and start of levothyroxine treatment up to 2 years of age. Results: Of the 380,741 live births, 3713 (1.04%) had filter paper TSH levels between 5 and 10 μIU/mL and, of these, 339 (9.13%) had congenital hypothyroidism. Of these, 76.11% of the cases were diagnosed in the first three months of life and 7.96% between 1 and 2 years of age. Conclusion: The study showed that 9.13% of the children with b-TSH levels between 5 and 10 μIU/mL developed hypothyroidism and that in approximately one-quarter of them, the diagnosis was confirmed only after the third month of life. Based on these findings, the authors suggest the use of a 5 μIU/mL cutoff for b-TSH levels and long-term follow-up of infants whose serum TSH has not normalized to rule out congenital hypothyroidism. Resumo: Objetivos: Determinar a prevalência de hipotireoidismo congênito em crianças com TSH em papel filtro (TSH-f) entre 5 e 10 μUI/mL na triagem neonatal. Métodos: Estudo retrospectivo incluindo crianças triadas de 2003 a 2010, com TSH-f entre 5 e 10 μUI/mL, que foram acompanhadas nos dois primeiros anos de vida quando não houve normalização do TSH sérico. O diagnóstico de hipotireoidismo congênito foi definido como TSH sérico igual ou superior a 10 μUI/mL e início de tratamento com levotiroxina até os dois anos de idade. Resultados: Dos 380.741 nascidos vivos triados, 3.713 (1,04%) apresentaram TSH-f entre 5 e 10 μUI/mL e, destes, 339 (9,13%) tinham hipotireoidismo congênito. Destes, 76,11% dos casos foram diagnosticados nos primeiros três meses de vida e 7,96% entre um e dois anos de idade. Conclusão: O estudo mostra que 9,13% das crianças com TSH-f entre 5 e 10 μUI/mL desenvolveram hipotireoidismo e que em cerca de um quarto delas o diagnóstico só se confirmou após o terceiro mês de vida. Com base nestes achados, sugere-se a utilização do ponto de corte de TSH-f de 5 μUI/mL e o acompanhamento em longo prazo dos lactentes cujo TSH sérico não tenha se normalizado para descartar o hipotireoidismo congênito. Keywords: Congenital hypothyroidism, Neonatal screening, Infant, Newborn, Thyroid diseases, Palavras-chave: Hipotireoidismo congênito, Triagem neonatal, Lactente, Recém-nascido, Doenças da glândula tireoide