Endocrine Abstracts

Background: Pregnancy is a state of a higher iodine intake demand. Proper iodine status is important during pregnancy for fetal neurodevelopment and maternal thyroid function. Urinary iodine concentration (UIC) is the most common indicator of iodine status.

Objectives: The aim of this study was to develop and validate a novel ion-pair HPLC-UV method to measure iodine in urine and to assess iodine status in pregnant women.

Methods: Sample preparation was performed by adding sodium thiosulfate solution to convert total free iodine in urine to iodide and precipitating the protein with acetonitrile. Separation was performed on a Pursuit XRs C8 column (250×4.0 mm, 5 μm). The mobile phase consisted of a mixture of water phase (containing 18-crown-6 ether, octylamine and sodium dihydrogen phosphate) and acetonitrile in the gradient elution at a flow rate of 1.2 ml/min.

Results: All the validation data, such as accuracy, precision and stability were within the required limits. The developed method was successfully applied to measure the urinary iodine concentration in 93 pregnant women. The overall prevalence of patients with the iodine concentration in urine<150 μg/l (iodine deficiency according to World Health Organization criteria) was 71%, while 21,5% had adequate concentrations. The median UIC in all pregnant women was 127.26 μg/l (%CI: 109.55; 144.96). The median UIC in pregnant women with iodine supplementation were higher compared with those who were not taking iodine-containing supplements (133.14 μg/l, 95%CI: 109.01;157.27 vs 116.82 μg/l, 95%CI: 95.27;138.37), but the difference was not statistically significant.

Conclusions: Established and validated ion-pair HPLC-UV method permitted the urine iodine analysis in pregnant females. Iodine status was insufficient during gestation. Therefore, the knowledge and awareness of the population in the field of iodine supplementation during pregnancy should be increased.