Background: Early miscarriages are of multifactorial origin. Subclinical thyroid dysfunction belongs to the common causes. Thyroid dysfunction in pregnancy is caused mainly by thyroid autoimmunity and/or iodine deficiency. The Czech Republic belongs to countries with sufficient iodine intake. The aim of the study was to determine iodine status in women after early miscarriages (n=183) and to compare it with randomly chosen age-comparable euthyroid women without previous pregnancy (controls, n=118).
Subjects and methods: A total of 183 consecutive women after miscarriage in the 912th weeks of pregnancy were included in the study. Within 3 months after miscarriage, we performed a laboratory assessment of urinary iodine concentration (UIC; absorption spectrophotometry) and an evaluation of the thyroid function including thyroid ultrasound. Seventy-two women were supplemented by iodine in previous pregnancy, 73 were not and in 38 the information wasnt available.
Results: Women after miscarriages had a significantly lower median of UIC as compared to controls (92 vs 108.6 μg/l, P<0.001). Furthermore, only 72/183 (39.3%) of women after miscarriage had sufficient iodine intake (UIC ≥100 μg/l) as compared to 71/118 (60.2%) in controls (P<0.001). In the rest of the samples analysed, we noted mild (UIC 5099 μg/l) and moderate iodine deficiency (UIC 2049 μg/l) without significant differences among the groups (57.9 vs 39.8% and 2.7 vs 0% respectively). None of the women analysed suffered from severe iodine insufficiency (UIC <20 μg/l). There were no significant differences in UIC between women supplemented with iodine in the previous pregnancy as compared to those who werent.
Conclusions: Czech women after miscarriages suffer from mild or moderate iodine deficiency significantly more often than healthy women without history of pregnancy. Our data support iodine supplementation in women attempting pregnancy even in iodine-sufficient countries.