Endocrine Abstracts

Iodine as the main component of thyroid hormones is an essential micronutrient for proper neurodevelopment. According to the WHO, its deficiency is the most common cause of preventable brain damage worldwide. Although most severe forms of iodine malnutrition have almost been eliminated, mild-to-moderate iodine deficiency is still very common, affecting approximately two billions people worldwide. Due to increased iodine requirements during gestation, iodine deficiency in pregnant women may be an issue even in populations considered iodine sufficient. Iodine deficiency is linked to the spectrum of health consequences defined as iodine deficiency disorders. Fetuses and young children are particularly vulnerable to deleterious effects of iodine malnutrition. It has been demonstrated in animal models that even mild iodine deficiency during gestation affects the brain cortex cytoarchitecture, glial development and myelinization in offspring, resulting in impaired learning capacity and behavioural changes. In humans consequences of severe iodine malnutrition, endemic cretinism included, have been well described. Prophylaxis with iodised oil in areas of severe iodine deficiency was proved to be effective in placebo-controlled randomised trials and resulted in a reduction of abortion, prematurity and stillbirth rates, as well as in decreased frequency of myxedematous cretinism. An evidence on the negative impact of mild-to-moderate iodine deficiency during pregnancy on children neurodevelopment is conflicting. Low iodine status in early pregnancy has been linked with lower verbal IQ and reading scores in the offspring (ALSPAC cohort), child language delay, behaviour problems, and reduced fine motor skills (Norwegian cohort) or lower spelling scores (Australian data). However, the association between children cognition and urinary iodine concentration during gestation has not been confirmed in a Dutch birth cohort, probably due to a low frequency of iodine deficiency in this group. The recently published results of randomised, placebo-controlled trial did not prove that iodine supplementation of mildly iodine deficient pregnant women influenced the neurocognitive development of their children.