Seasonality in urinary and household salt iodine content among pregnant and lactating women of the plains of Nepal

Abstract

Objective: To determine the extent and causes of iodine deficiency among women during pregnancy and lactation in the southeastern plains of Nepal. Design, Setting and Subjects: Urinary iodine (UI) was assessed as an indicator of iodine status in spot urine samples of women participating in a field trial in three rural communities in the plains of southeastern Nepal. Samples were collected during pregnancy (n ¼ 1021) and during lactation at 3-4 months postpartum (n ¼ 1028) at a central clinic; 613 women were assessed at both times. Salt iodine (SI) content was assessed semiquantitatively at 6-7 months postpartum in households (n ¼ 1572). Results: During pregnancy and lactation, median UI concentrations were 0.756 and 0.483 mmol/l, respectively, indicating mild iodine deficiency. UI and SI concentrations covaried markedly by season and were highest during hot, dry, premonsoon months and lowest during and following the humid monsoon season. Within women who contributed urine samples during both pregnancy and the postpartum period, iodine status determined by UI was not correlated. The percentage of households with adequately iodized salt (30 ppm) ranged from 85 to 44% from the hot, dry to the humid seasons, respectively. Conclusions: In the rural southern plains of Nepal, iodine deficiency remains a mild-to-moderate public health problem among pregnant and lactating women despite the availability of iodized salt. Marked seasonality in SI content may account for the lack of intraindividual correlation between maternal iodine status during pregnancy and postpartum periods and contribute to periodicity in the risk of iodine deficiency.

Iodine Nutrition: Iodine Content of Iodized Salt in the United States

“…Inhomogeneity is not therefore rare; the large inhomogeneity found in some samples is worrisome. Although a similar study has not been conducted in the United States, an extensive study in Nepal showed that as salt iodine content varies as a function of season (decreasing in more humid weather), a similar variation in UI is observed (88) suggesting that salt is an important source of iodine. If salt does supply a significant portion of the iodine intake of a pregnant/lactating woman in the United States (note that a large fraction of preor postnatal vitamins contain no iodine) and she is unfortunate enough to pick a can of salt that is low in iodine or in which iodine distribution is greatly inhomogeneous, there is potential for serious harm.…”

Iodine and Thyroid Function Status, and Anti-thyroid Peroxidase Antibody among Pregnant Women in Eastern Nepal

“…Pregnant women require 250 μg intake of iodine per day, and UIC is a good indicator of recent iodine intake. 2,13 The median UIC among pregnant women in the present study was 282.2 μg/L, which indicates more than adequate iodine intake among pregnant women of eastern Nepal. However, 17 (18.5%) women had UIC<150 μg/L, which indicates insufficient iodine intake in those women recently.…”

Iodine-induced goitre and high prevalence of anaemia among Saharawi refugee women

“…The other determinant of UIC was breast-feeding, where breast-feeding women had a significantly lower UIC than women who were not breast-feeding. Reduced UIC during breast-feeding has been found in other studies (30)(31)(32) and is probably a reflection of the iodine excretion in breast milk (33) .…”