Endocrine Abstracts

Objective: No consensus has been reached yet on whether iodine supplementation should be recommended also in pregnant women with Hashimoto’s thyroiditis who are receiving levothyroxine (LT4) therapy. We aimed to evaluating the iodine status in a sample of pregnant women residing in the Veneto region of Italy and suffering from autoimmune thyroiditis. Here we present our preliminary results.

Methods: 81 pregnant women with Hashimoto’s thyroiditis, whether or not undergoing LT4 therapy, were consecutively enrolled. Inclusion criteria were women aged more than 18 years old, resident in Veneto and agreeing to participate in the study; exclusion criteria were non-autoimmune hyperthyroidism or iatrogenic hypothyroidism. Data on participants’ dietary habits, iodine containing supplements (IS) use and social status were collected through a questionnaire. Serum TSH and FT4 and an early-morning spot urine sample to determine the iodine to creatinine concentration ratio (UI/Creat) were taken. Children’s’ anthropometric data, gestational age at birth, sex and neonatal TSH value were collected.

Results: a median UI/Creat value of 276 μg/g and a more than adequate level of UI/Creat (≥250 μg/g) was found in 57.1%, while in 27.2% a state of iodine deficiency (<150 μg/g) was observed. Patients on LT4 therapy accounted for 92.6% and, in this group, the median UI/Creat value was 286 μg/g. Iodized salt was consumed by 82.7% but was not associated with median UI/Creat. UI/Creat was, associated with regular cheese consumption (364 μg/g vs 238 μg/g, P = 0.03). Median UI/Creat was 289 μg/g in IS-users and 124.5 μg/g in non-users (P = 0.054), with iodine deficiency in 66.7% of the latter vs 23.9% in the former (P = 0.02). A positive weak correlation, at the limit of significance (P = 0.057, r = 0.22) was found between daily L-T4/Kg and UI/Creat. At multivariate analysis the supplement intake was the only independent variable for adequate UI/Creat (OR: 6.35; CI: 1.07-37.8; P = 0.04). Higher neonatal weight was associated, at the limits of statistical significance (P = 0.056), with an UI/Creat ≥250 μg/g and higher neonatal TSH values (2.5 mIU/l vs 1.2 mIU/l) were found in the group of women taking the supplement.

Conclusions: Although the intake of LT4 and supplementation contributed to the elevation of median iodide levels, failure to use it resulted in a tendency to iodine deficiency. Iodine supplementation resulted in in higher neonatal TSH values, although in the normal range. A moderate iodine supplementation in women with autoimmune thyroiditis undergoing LT4 therapy should be taken into consideration, also based on their L-T4 dose.