Clinical and laboratory features of children and adolescents with congenital hypothyroidism due to dyshormonogenesis in southern Brazil / Características clínicas e laboratoriais de crianças e adolescentes com hipotireoidismo congênito devido a disormonogênese no sul do Brasil

OBJECTIVE: To characterize the phenotype of patients with congenital hypothyroidism (CH) due to dyshormonogenesis, and to hypothesize on the degree of genetic defect. SUBJECTS AND METHODS: Patients with dyshormonogenesis were subdivided into G1 (radioactive iodine uptake, RAIU > 15%; n = 62) and G2 (RAIU < 15%; n = 32). Thyroglobulin (TG) was measured in all patients; perchlorate discharge test (PDT) was performed in G1; and saliva-to-plasma radioiodine ratio (I- S/P) in G2. RESULTS: Levels of TSH, TT4, and FT4 before treatment and upon diagnosis confirmation were significantly different in both groups, but not between groups. In G1, 27 patients developed goiter; 17 had positive PDT (14%-71% discharge), 11 had TG < 2.5 ng/dL (one with high TSH), and one developed thyroid carcinoma. In G2, four patients developed goiter, and three had low I- S/P. CONCLUSION: These data suggest an iodide organification defect in 17 cases; an iodide transport defect (NIS defect) in three, probable TSH resistance in 10, and a TG synthesis defect in two cases.

OBJETIVO: Caracterizar o fenótipo de pacientes com hipotireoidismo congênito (HC) por disormonogênese e sugerir o nível do defeito genético. SUJEITOS E MÉTODOS: Pacientes com disormonogênese foram subdivididos em G1 (captação de 131I > 15%; n = 62) e G2 (captação < 15%; n = 32). Tireoglobulina (TG) foi dosada em todos, teste de descarga do perclorato (TDP) foi realizado no G1 e relação iodo salivar/sérico (I- S/P), no G2. RESULTADOS: Os valores de TSH, T4T e T4L pré-tratamento e na confirmação do diagnóstico foram significativamente diferentes em ambos os grupos (p < 0,01), mas não entre eles. No G1, 27 pacientes desenvolveram bócio; TDP foi positivo em 17 (descarga de 14%-71%); 11 tiveram TG < 2,5 ng/dL (um com TSH elevado) e um desenvolveu carcinoma de tireoide. No G2, quatro pacientes desenvolveram bócio e três apresentaram baixa I- S/P. CONCLUSÃO: Esses dados sugerem defeito na organificação do iodeto em 17 casos; defeito no transporte do iodeto (defeito na NIS) em três, provável resistência ao TSH em 10 e defeito na síntese de TG em dois.

Nutrición de yodo en escolares de una zona con alta ingesta de yodo (Calama)comparada con zona de ingesta normal (Punta Arenas) / Iodine nutritional status in school-age children from an area of high iodine intake (Calama) compared with an area of normal intake (Punta Arenas)

Se evaluó la prevalencia de bocio por palpación de la glándula tiroidea en 1296 escolares de educación básica de una zona con alta ingesta de yodo (Calama) y se comparó con la de otra zona de ingesta normal de yodo (Punta Arenas). En una sub muestra del 10 por ciento de los escolares se midió la excreción de yodo urinaria y los niveles de hormonas tiroídeas en sangre. En ambas localidades se seleccionaron aleatoriamente del comercio 148 muestras de sal para consumo humano en las que se determinó la concentración de yodo. Se encontró una prevalencia de bocio de 11,1 por ciento (10,0 por ciento en varones y 12,5 por ciento en mujeres) mayoritariamente bocio grado Ia (7,2por ciento), sin diferencias por zona (11,6 por ciento en Calama y 10,6 por ciento en Punta Arenas). La concentración de yodo en la sal de consumo humano en ambas localidades fue adecuada a la exigencia actual del Reglamento Sanitario de los Alimentos (RSA) (33,3 µgI/g sal en Calama, 34,0 en Punta Arenas). La excreción de yodo en la orina fue significativamente más alta en Calama (460 ± 190 µgI/L)que en Punta Arenas (273 ± 155). No se detectaron diferencias en los niveles de T4 y TSH (Calama 7.1 ± 1.5 y 3.3 ± 1.8 y Punta Arenas 7.2 ± 1.1 y 2.9 ± 1.2 respectivamente) en tanto que las valores de T3 en ambas localidades mostraron diferencias significativas (103.9 ± 33.1 y 145.0 ± 26.0 respectivamente, p<0.001) . Se observó sólo una tendencia al aumento de la prevalencia de bocio, con persistencia de valores elevados de yoduria en Calama, lo que sugiere una fuente de yodo extra en esta localidad, cuya procedencia desconocemos y es necesario investigar.

Goiter prevalence determined by palpation of thyroid gland was evaluated in 1296 primary school age children from an area of high iodine intake (Calama) and compared with an area of normal iodine intake (Punta Arenas). Urinary iodine excretion and plasmatic thyroid hormones were measured in 10 percent of school children. In both areas 148 samples of salt for human consumption were randomly selected to measure iodine concentration. A goiter prevalence of 11,1 percent (10,0 percent in males and 12,5 percent in females) mainly goiter grade Ia (7,2 percent), without differences per area (11,6 percent in Calama and 10,6 percent in Punta Arenas) was found. Iodine concentration in salt for human consumption at both areas was adequated according the present Food Sanitary Regulation (FSR) in Chile (33,3 (gI/g salt in Calama, and 34,0 in Punta Arenas). Urinary iodine excretion was significantly higher in Calama (460 ( 190 (g I/L) than in Punta Arenas (273 ( 155 (g I/L). No differences were detected in T4 and TSH plasma levels (Calama 7.1 ( 1.5 and 3.3 (1.8; and Punta Arenas 7.2 ( 1.1 and 2.9 ( 1.2 respectively), while T3 plasma levels were significantly higher in Punta Arenas (103.9 ( 33.1 y 145.0 ( 26.0 respectivamente, p<0.001) . Only a tendency to a higher goiter prevalence with persistent and significantly higher urinary iodine excretion in children at Calama was observed, suggesting an extra source of iodine in this area, with an unkown origen that must be investigated.

Micronutrients and its correlation with mental performance among schoolchildren in Bario, Sarawak: a preliminary study

Children who are born in a community with insufficient micronutrients, particularly iodine in remote rural areas are associated with low intellectual functions and mental retardation. The aim of this cross-sectional study is to determine the mental performance of the schoolchildren in Bario, a highland settlement of the Kelabit people in the district of Baram, Sarawak and to determine its correlation with the availability of iodine in the environment, as well as other micronutrients such as selenium, copper and manganese. A total of 25 schoolchildren in Bario age ranging from 7 to 12 years old participated in the study. Mental performance of the schoolchildren were tested using TONI-2 (Test of Nonverbal Intelligence--second edition), a cognitive ability measures with a response format which eliminates language and reduces motoric and cultural factors. The iodine levels from several wells, soils and salt found in Bario were determined using HPLC (software version 3.05.01) whilst serum levels of selenium, copper and manganese were measured using Graphite Furnace Atomic Absorption Spectrophotometer (GFAAS). The results showed that the median and mode scores of intelligence quotient for Bario were 82 and 75, respectively, whilst median and mode scores of intelligence percentile were 11.0 and 5.0, respectively. The maximum score achieved were at the average level with the quotient score between 90-110. It was found that salt produced from one of the wells in Bario contained high quantity of iodine. Based on standards established by the Trace Elements Laboratory, Roben Institute, University of Surrey, United Kingdom, schoolchildren in Bario are having sufficient blood levels of copper and a high selenium and manganese levels. Despite the remoteness of the study area, the schoolchildren in Bario, Sarawak showed higher mental performance compared to other isolated areas. This is probably correlated with the high micronutrients availability, particularly iodine, found naturally in Bario.