Thyroid dysfunction tied to poor development in children with iodine excess
In children with chronic excessive exposure to iodine, thyroid dysfunction is associated with impaired development, a recent study shows.
“The high iodine intake may have caused the thyroid dysfunction and hence the delayed developmental status; however, other influential factors cannot be excluded,” said the researchers.
The study included 298 children (median age 31.4 months; 52.3 percent female), in whom urinary iodine concentrations (UIC) were measured. None of the participants were taking thyroid hormones or had known thyroid disease.
The third edition of the ages and stages questionnaire (ASQ-3) was used to evaluate child development. Thyroid function was assessed using concentrations of the thyroid hormones serum thyrotropin (TSH), free thyroxin and free triiodothyronine.
The median UIC in the cohort was 451.6 µg/L, while the median ASQ-3 score was 180 with scores ranging from 45 to 270.
In the unadjusted models, thyroid disturbance (odds ratio [OR], 0.49; 95 percent CI, 0.25 to 0.95; p<0.05) and having TSH levels outside the reference (OR, 0.40; 0.19 to 0.88; p<0.05) significantly reduced the chances of being in the top two tertiles of ASQ-3 scores. The respective associations were attenuated after adjusting for potential confounders (OR, 0.51; 0.25 to 1.02; p=0.058 and OR, 0.48; 0.22 to 1.08; p=0.075).
Because the general motor subscale of the ASQ-3 was found to have poor discriminatory ability, the researchers repeated the above analysis excluding this domain. Results showed that thyroid disturbance (OR, 0.46; 0.23 to 0.93; p<0.05) and having TSH concentrations outside the reference (OR, 0.42; 0.19 to 0.94; p<0.05) were significantly associated with lower chances of being in the top two tertiles of ASQ-3 scores, even in the adjusted models.