Excessive Iodine Intake and Ultrasonographic Thyroid Abnormalities in Schoolchildren

Abstract

High nutritional levels of iodine may induce a higher prevalence of autoimmune thyroiditis, hypothyroidism, goiter, as well as hyperthyroidism, mostly in the elderly. This study assessed thyroid volume and ultrasonographic abnormalities as well as urinary iodine excretion (UIE) in 964 schoolchildren living in an iodine-sufficient area in southern Brazil. Thyroid volume correlated with age and body surface area in boys and girls. In 76.8% of the children, UIE was above 300 microg/l, with higher levels among boys compared to girls (484.2 microg/l vs 435.3 microg/l, p < 0.001). Thyroid abnormalities detected by ultrasonography included hemiagenesis (0.5%), nodules (0.2%), cysts (0.7%), and hypoechogenicity (11.7%). Goiter was present in 1.9% of the children. Hypoechogenicity, a relevant marker of autoimmune thyroiditis, was the most common abnormality found in our study, and this may be linked to excessive iodine intake.

Etiology of congenital hypothyroidism using thyroglobulin and ultrasound combination

“…Moreover, it can be performed at any time without preparation or interruption of treatment. CDUS proved accurate for diagnosing thyroid hypoplasia in our study, using height reference for normal volume in the Brazilian pre-school population [23,25]. We did not find the best reference for normal thyroid volume in childhood.…”

“…Total thyroid volume was calculated as described elsewhere [23] and compared according to height [24], sex and age, body surface and sex [23,25]. Two investigators analyzed the images of ultrasonography independently and the results were compared.…”

Associations between iodine intake, thyroid volume, and goiter rate in school-aged Chinese children from areas with high iodine drinking water concentrations

“…The TGR increased from 12% to 38% as the median UIC increased from 520 to 1961 mg/L in Jiangsu province (11). Increased Tvols observed in Southern Brazil have been attributed to excessive iodine exposure (12). However, high TGRs have also been reported in populations with adequate UIC concentrations during the period of transition from iodine deficiency to iodine sufficiency (13)(14)(15).…”

Alta frecuencia de anticuerpos anti-tiroperoxidasa (ATPO) positivos en sujetos adultos, sin patología tiroidea conocida, de Santiago de Chile

“…Muzzo et al han demostrado en población escolar chilena una elevada excreción urinaria de yodo 22 . Series europeas y sudamericanas han demostrado un incremento de los títulos de anticuerpos antitiroideos, tiroiditis crónica demostrada por ecografía o histología y también de cáncer diferenciado de tiroides [23][24][25][26] . Otros autores han demostrado que en pacientes con hipotiroidismo subclínico, una mayor excreción urinaria de yodo se relaciona con un aumento más precoz de la TSH y de los anti-TPO 27 .…”