The effect of iodine supplementation on thyroid volume and thyroid stimulating hormone level in women of childbearing age residing in West Azarbaijan province, Iran

Iodine as an essential element is required for biosynthesis of thyroid hormones as well as for the development of the nervous system of the fetus. Therefore, the consumption of an extra dose of iodine ranging from 150-250 µg/day has been recommended for women planning a pregnancy or at early stage of maternity by world health organizations. This study was designed to evaluate the effect of iodine supplementation (150 μg/d) for 90 days on thyroid volume and thyroid stimulating hormone (TSH) in women of reproductive age in West Azarbaijan province, Iran. In this study, 38 women were enrolled (Age: 20-30 years). Inclusion criteria were non-pregnant students, at least one-year residency in student dormitory and no history of thyroid disorders. Thyroid volume was measured by a Philips Affiniti 50 ultrasound. Serum TSH measurements were performed by Liason instrument. Data analysis was performed using SPSS software version 16. The mean age and body mass index (BMI) of the studied population were 24.1 ± 2.59 years and 21.35 ± 2.2 kg / m2. At baseline and 90 day post iodine supplementation, mean total thyroid volume, right lobe and left lobe were 7.07 ± 2.47 ml vs 6.06 ± 0.54 ml; 3.31 ± 1.39 ml vs 3.31 ± 0.86 ml and 2.49 ± 1.21, 2.74 ± 0.79 ml. Paired t test showed the reductions in thyroid size were statistically significant (P<0.05). a significant decrease in The mean volume of left, right and left lobes volume and total thyroid volume after the supplementation stage was shown to be significant (P <0.05). There was no relationship between BMI, body surface area (BSA) or thyroid volume. No difference was detected in TSH levels before and after the iodine treatment (2.13 ± 1.02 mIU/L vs 2.37 ± 1.31 mIU/L). This study reveals that the iodine intervention three months was associated with a 14.28% reduction in to total thyroid volume. On the other hand, the treatment had no effect on the level of TSH. The marked reduction in thyroid volume combined with the a large between individual coefficient of variation in the right lobe and left lobe after the exposure to iodine treatment suggest that assessment of the thyroid size is a sensitive and non-invasive method for longitudinal study exploring the benefits and harms of iodine therapy. Further studies with larger sample size and longer follow-up time point and in combination with urinary iodine excretion, serum thyroglobulin and thyroid-autoimmunity biomarkers are needed to confirm the findings of this preliminary study.