Endocrine Abstracts

Background: Despite obligatory iodination of salt in the Czech Republic, pregnant women with higher demands on iodine intake may be at risk of iodine deficiency with potentially negative consequences for the course of pregnancy and foetal development. Determination of urinary iodine concentration (UIC) is a conventional but not widely available method used to estimate the iodine status. Based on previous studies, serum thyroglobulin (Tg) could serve as a more convenient marker of iodine deficiency in preschool children and adults. This study aimed to investigate the potential use of Tg as a marker of iodine status in pregnancy.

Patients and methods: UIC from the morning urine sample, biochemical thyroid tests — serum concentration of thyroid stimulating hormone (TSH), free thyroxine (FT4), antibodies to thyroid peroxidase (TPOAb) and thyroglobulin (TgAb) and serum thyroglobulin (Tg) were measured, and thyroid ultrasound (US) was performed in 187 pregnant women in the first trimester of pregnancy.

Results: Overall, inadequate iodine supply in the investigated group of pregnant women was found (median UIC 119.2 μg/l). In the group of women taking oral iodine supplements with ≥ 100 μg of elemental iodine daily, the IUC was significantly higher compared to the group of women taking supplements with 100 μg of iodine or no supplements (median IUC 137.85 μg/l vs. 103.50 μg/l, P= 0.002). We found no significant correlation between serum Tg and UIC. Serum Tg was significantly higher in euthyroid TPOAb positive women with US pattern of autoimmune thyroiditis as compared to euthyroid TPOAb positive women with normal US and controls (median Tg 25.65, 7.9 and 8.5 μg/l, respectively, P=0.0009).

Conclusions: Serum Tg was no reliable marker of iodine deficiency in pregnant women in our study. In TPOAb-positive women, serum Tg could distinguish between actual autoimmune inflammation of the thyroid gland and simple serum TPOAb positivity, but further studies are needed. The study was supported by the Charles University, project GA UK No. 265221