Urinary iodine and thyroid determinants in pregnancy: a follow up study in Sri Lanka

Abstract

BackgroundIodine deficiency and thyroid dysfunction during pregnancy is associated with number of adverse outcomes that includes mental and physical disabilities creating a huge human and economic burden in later life. Several indicators are used to assess the iodine status of a population: thyroid size by palpation and/or by ultrasonography, urinary iodine excretion and the blood thyroid hormone profile.MethodsThis prospective study was designed to assess the iodine nutrition during the course of pregnancy with reference to urine iodine concentration (UIC) and thyroid determinants among 425 pregnant women from Galle district, Sri Lanka. UIC was estimated in all three trimesters and thyroid functions were assessed in first and third trimesters.ResultsMedian (inter-quartile range IQR) UIC was 170.9 (100.0–261.10) μg/L, 123.80 (73.50–189.50) μg/L and 105.95 (67.00–153.50) μg/L in the first, second and third trimesters respectively (p < 0.001). Median thyroid stimulating hormone (TSH) level in the first trimester was 1.30 (0.80–1.80) µIU/mL. This value significantly increased (p < 0.001) to 1.60 (1.20–2.10) µIU/mL at the 3rd trimester even though it was maintained within the reference range (0.3 – 5.2 µIU/mL). In the assessment of thyroid gland, 67 (16.0 %) women had palpable or visible goitres and 55 (13.1 %) had a goitre that was palpable but not visible. The median thyroid volume of the sample was 5.16 mL (4.30; 6.10 mL) as measured by ultra sound (US) scanning. In multiple regression analysis after controlling for other independent variables (anthropometric, demographic and biochemical parameters); initial body mass index (BMI), goitre size, thyroid volume and parity had significant correlations with the third trimester urinary iodine levels. The thyroid volume accounted for 4.5 % of the urinary iodine variation.ConclusionsEven though iodine status was progressively worsening with the advancement of pregnancy and iodized salt consumption has not met with the increasing demand for iodine, it was not reflected in the serum TSH level. Therefore, it is worthwhile to assess the long term effects of rising TSH levels and inadequate iodine nutrition during pregnancy on the offspring to prevent even mild iodine deficiency.

Relationship of household cooking salt and eating out on iodine status of pregnant women in environmental iodine-deficient coastal areas of China

“…However, the UIC in the third trimester of pregnancy was obvious low. These results are consistent with previous studies in Australia and Sri Lanka, both of which suggest that women in the third trimester of pregnancy have a higher risk of iodine deficiency (26,27) . In Shanghai, it is therefore necessary to remind pregnant women in the third trimester to take an iodine supplement or to choose iodine-rich food.…”

Trimester-Specific Thyroid Function in Pregnant Women with Different Iodine Statuses

“…In the current study, we observed that FT3 and FT4 were significantly decreased from the first trimester to the third trimester, in line with previous studies [8,9]. Weeke et al [10] found that TSH level in pregnant women in- creased as pregnancy advanced and was significantly different from the postpartum value.…”

Maternal and neonatal outcomes and determinants of iodine deficiency in third trimester of pregnancy in an iodine sufficient area

“…In another study on pregnant women in the rural area of Bangladesh, the prevalence of inadequate iodine intake was reported to be 6% and excessive iodine intake was 10% [23]. Zoysa et al [24] in their study depicted that the prevalence of trimester-specific insufficient intake of urinary iodine in line with the World Health Organization criteria were 34.7, 45 and 62.2% in first, second, and third trimesters, respectively. These results were very similar to those of the present study, but the prevalence in the third trimester was less prevalent in the current study.…”