Evaluation of urinary iodine concentration, thyroid volume, and thyroid function in the first trimester of pregnancy

Introduction

Iodine is a crucial element for thyroid hormone synthesis and plays an important role in regulating the body’s basal metabolism. The aim of our study was to evaluate iodine status, thyroid volume, and thyroid function in pregnant women during the first trimester of pregnancy. Material and methods: This study included 130 healthy pregnant women in their first trimester between November 2022 and May 2024. However, urinary iodine concentration (UIC) data could not be obtained for two participants, and urinary iodine/creatinine ratio data were missing for four participants because of insufficient sample volume. Laboratory tests, including free triiodothyronine (fT3), free thyroxine (fT4), thyroid-stimulating hormone (TSH), and thyroglobulin (Tg), were performed. First-morning single-spot urine samples were collected, and urinary iodine and creatinine concentrations were determined. The urine iodine/creatinine ratio (μg/g) was calculated using the following equation: urine iodine (μg/L)/urine creatinine (mg/dL) × 100. The thyroid gland, including thyroid volume, was evaluated using ultrasonography.