Iodine status in healthy pregnant women in Korea: a first report

PURPOSE: Proper iodine intake is important during pregnancy for both fetal neurodevelopment and maternal thyroid function. Korea is known as a high iodine intake area. However, there are no data regarding iodine status in pregnant Korean women. Therefore, we evaluated the iodine status of pregnant women in Korea by measuring urine iodine concentration. METHODS: This study had an observational, prospective design. We enrolled 344 healthy pregnant women who visited Samsung Medical Center in Korea for a routine antenatal checkup between April 2012 and September 2013. We measured iodine and creatinine concentration (Cr) in spot urine samples and TSH level in serum at the time of enrollment. RESULTS: The median urinary iodine concentration (UIC) and UIC adjusted by Cr were 427.3 μg/L and 447.9 μg/gCr, respectively. There was no difference in median UIC according to trimester of pregnancy (P value = 0.953). Serum TSH level was not different according to UIC level when subjects were grouped according to WHO iodine recommendations (P value = 0.401). CONCLUSIONS: The median UIC of healthy pregnant women in Korea was 427.3 μg/L and 447.9 μg/gCr, which are more than adequate according to WHO criteria. Considering the wide range of UIC, we recommend active education about adequate iodine intake during pregnancy in areas where iodine intake is more than adequate according to WHO criteria.