The objective of the study was to assess the effect of iodine supplementation on goiter and thyroid hormone markers of lactating women in rural Ethiopia.
This study was conducted in a population with long history of severe iodine deficiency. In this study 101 lactating women were recruited and randomly assigned to receive iodine capsule (225 µg iodine) daily for 26 weeks or iodized salt (450 g for household consumption) weekly for 26 weeks.
At baseline women were not significantly different in goiter rate, thyroid hormones (T3 & T4), thyroid stimulating hormone (TSH) or thyroglobulin (Tg). At 26 weeks goiter rate significantly decreased from 76% to 30% in the capsule group and from 74% to 43% in the iodized salt group. TSH and T3 significantly decreased at 26 weeks and T4 decreased in both groups but the decrease was significant only in the salt group (p < 0.001). Tg showed no significant change. Except T4 (p = 0.014), no biomarker had treatment by time interaction. The proportion of mothers with subclinical hypothyroidism significantly decreased at 26 weeks compared to baseline. The incidence of hypothyroxinemia in mothers significantly increased in the salt group. Among the markers tested in this study only TSH was positively associated with goiter (Chi-square = 5.8, p = 0.016).
Because median iodine was sufficient as measured by urinary and breast milk iodine concentrations, thyroid hormone markers may not have responded to iodine supplement as expected. However, the association between goiter and thyroid hormones needs further investigation.