J. G Vieira

Comparação entre duas estratégias para a detecção precoce do hipotiroidismo congênito

OBJECTIVE: Compare two different strategies in newborn screening for congenital hypothyroidism, primary TSH in the umbilical cord blood (method 1) and primary T4 in blood collected from the heel in the 2nd day of life (method 2). METHODS: We compared both strategies in 10,000 newborns, measuring TSH by a sensitive immunofluorimetric assay and T4 by a radioimmunoassay. RESULTS: Both strategies detected all cases of hypothyroidism (4 cases, 1/2,500 newborns). The recalling index owing to insufficient amount of blood to perform the assays was zero in method 1 and 8.5% (850 newborns) in method 2. The recalling index for confirmation of the results was 0.06% (6 newborns) in method 1 and 2.25% (225 newborns) in method 2; when method 2 included supplementary TSH, the recalling index was reduced to 1.63% (163 newborns). CONCLUSION: Our data indicate the technical superiority of the umbilical cord blood compared to heel and primary TSH compared to primary T4 in the neonatal thyroid screening for congenital hypothyroidism.OBJECTIVE Compare two different strategies in newborn screening for congenital hypothyroidism, primary TSH in the umbilical cord blood (method 1) and primary T4 in blood collected from the heel in the 2nd day of life (method 2). METHODS We compared both strategies in 10,000 newborns, measuring TSH by a sensitive immunofluorimetric assay and T4 by a radioimmunoassay. RESULTS Both strategies detected all cases of hypothyroidism (4 cases, 1/2,500 newborns). The recalling index owing to insufficient amount of blood to perform the assays was zero in method 1 and 8.5% (850 newborns) in method 2. The recalling index for confirmation of the results was 0.06% (6 newborns) in method 1 and 2.25% (225 newborns) in method 2; when method 2 included supplementary TSH, the recalling index was reduced to 1.63% (163 newborns). CONCLUSION Our data indicate the technical superiority of the umbilical cord blood compared to heel and primary TSH compared to primary T4 in the neonatal thyroid screening for congenital hypothyroidism.

Hipocalcemia e síndrome convulsiva em alcoólatras - uma associação freqüentemente não diagnosticada

Hipocalcemia e um fator importante contribuinte para a epilepsia, e estudos anteriores mostraram que o etanol diminui o calcio plasmatico. OBJETIVO: Estabelecer a prevalencia de hipocalcemia na populacao convulsiva em geral e identificar um subgrupo especifico de risco para hipocalcemia. METODOS: Realizamos um estudo prospectivo de dosagem de calcio ionizado plasmatico em 78 pacientes consecutivos admitidos no Servico de Emergencia da Escola Paulista de Medicina devido a sindrome convulsiva. Desses pacientes, 22% eram alcoolatras. Foi tambem dosado o calcio ionizado plasmatico numa populacao de 44 alcoolatras nao-convulsivos em seguimento ambulatorial. RESULTADOS: Uma alta prevalencia de hipocalcemia foi encontrada na populacao alcoolatra convulsiva (32%), em contraste com os convulsivos nao-alcoolatras e o grupo alcoolatra nao-convulsivo (ambos os grupos sem disturbio do calcio). O calcio ionizado plasmatico do grupo de alcoolatras convulsivos teve valores significantemente menores que o grupo de convulsivos nao-alcoolatras (p<0,05) [mediana de 1,20; variacao entre 1,04 e 1,32mmol/L/; mediana de 1,24; variacao entre 1,16 e 1,29mmol/L, respectivamente]. O grupo de alcoolatras nao-convulsivos apresentou valores de calcio ionizado entre 1,17 e 1,32mmol/L, com mediana de 1,26mmol/L. Estes valores nao diferiram dos obtidos nos convulsivos nao-alcoolatras, mas foram significantemente maiores que os do grupo de alcoolatras convulsivos (p<0,05). Os niveis de paratormonio serico, funcao hepatica, fosfatemia e amilasemia estavam normais em todos os pacientes estudados. CONCLUSAO: Este estudo mostra a importância da dosagem de calcio plasmatico em pacientes alcoolatras com sindrome convulsiva e sugere que a correcao da hipocalcemia possa ser medida importante a ser adotada nestes casos.

Desenvolvimento de um radioimunoensaio de dexametasona no soro como subsídio para o diagnóstico da síndrome de Cushing

INTRODUCTION: The 1 mg dexamethasone suppression test (DxST) is widely used to screen Cushings syndrome (CS) due to its high diagnostic accuracy. CS is an endocrine-metabolic disorder caused by hypercorticism, which is characterized by the absence of cortisol suppression in DxST. OBJECTIVE: To develop a radioimmunoassay (RIA) for the measurement of serum dexamethasone (Dx) to complement DxST. METHODS: Three rabbits were inoculated with dexamethasone-21-hemisuccinate-BSA in order to choose the best antibody. Serum Dx RIA was performed according to RE 899/2003 (Agencia Nacional de Vigilância Sanitaria [ANVISA]) regulations. Serum samples from 96 volunteers from Universidade Federal de Sao Paulo (UNIFESP) and Santa Casa de Misericordia de Sao Paulo were analyzed, 67 of which were submitted to DxST and 29 were not. There were 12 patients with CS. RESULTS: The Dx antibody chosen showed good specificity. Intra- and interassay CV were < 20% with 93.8% accuracy and the lowest detection limit was 19.5 ng/dl. Serum Dx concentration was similar among both volunteers and CS patients (absence of cortisol suppression): 205 to 703 ng/dl and 174 to 661 ng/dl (95% CI), respectively. Values were undetectable among those that were not submitted to the test. Discussion: The anti-Dx antibody shows high specificity and reliability to quantify serum Dx in DxST. The Dx RIA presented reproducibility and reliability in the determination of serum Dx levels during DxST. CONCLUSION: The current RIA for serum Dx is accurate and reliable, which permits to establish a reference value range to substantiate DxST interpretation.

Calcitonina monomérica plasmática e hipercalcemia em pacientes portadores de neoplasia pulmonar

BACKGROUND. Calcitonin (CT) is a peptidic hormone produced by the thyroid C cells and related to calcium metabolism. High plasmatic levels of this hormone are found in patients with medullary thyroid carcinoma, what makes it an excellent tumor marker for this disease. However, there are reports that showed an increase of plasmatic CT levels in patients with other tumors, mainly in lung cancer. PURPOSE. These data prompt us to investigate the validity of the CT level determinations as a potential tumor marker in different histologic lung cancer, and its correlation with hypercalcemia, a very common complication in these tumors. METHOD. Blood were sampled from 56 patients with malignant lung disease for the CT and ionized calcium determinations. Calcitonin was measured using a specific radioimmunoassay for the monomeric form of the molecule, in a previous silica extracted serum probe. RESULTS. We did not find elevated levels of monomeric CT in lung cancer. Only 3 patients had mild elevated levels, while in the others CT was normal or undetectable. Hypercalcemia was found in 21.4% of these patients, but only one with supranormal CT levels. CONCLUSION. Monomeric CT serum levels are normal in lung cancer, what makes the latter use an unreliable tumor marker.