High Prevalence of Low Urinary Iodine among Pregnant and Lactating Women of Bangladesh Does Not Respond to Daily Lipid‐based Nutrient Supplement Containing 250 μg Iodine
Authors: Mridha Malay Kanti , Matias Susana L , Khan Showkat Ali , Paul Rina Rani , Siddiqui Zakia , Ullah Barkat , Hussain Sohrab , Young Rebecca Tree , Arnold Charles D , Dewey Kathryn G 
Published: June 2021

Objective

Iodine deficiency during pregnancy and lactation is common in Bangladesh. We evaluated the effect of lipid‐based nutrient supplements for pregnant and lactating women (LNS‐PL) on urinary iodine (UI) levels.

Method

We conducted a cluster‐randomized effectiveness trial (the Rang‐Din Nutrition Study) in which we enrolled 4011 pregnant women at < 20 gestational weeks. Women in 48 clusters received iron and folic acid (IFA; 60 mg iron + 400 μg folic acid) and in 16 clusters received LNS‐PL (20 g/d, 118 kcal) containing essential fatty acids and 22 vitamins and minerals (including 250 μg of iodine). LNS‐PL was consumed daily during pregnancy and 6 months postpartum; and IFA was consumed daily during pregnancy and on every alternate day during the first 3 months postpartum. We collected urine samples (2 ml each) from a randomly selected sub‐sample of women. UI was analyzed using the microplate method described by Ohashi and colleagues. Three cut‐offs of iodine deficiency were used for the analysis (UI < 150 μg/L, < 100 μg/L, and < 50 μg/L).

Results

We analyzed UI of 1124 (504 in the IFA and 620 in the LNS‐PL), 867 (391 in IFA and 476 in LNS‐PL), and 1041 (464 in IFA and 577 in the LNS‐PL) women at baseline (mean ~13 weeks gestation), 36 weeks gestation and 6 months postpartum, respectively. Mean unadjusted and adjusted log UI at 36 weeks gestation and 6 months postpartum was not significantly different between the IFA and LNS‐PL groups, nor were the changes in log UI between baseline and 36 weeks gestation or between baseline and 6 months postpartum. Almost all the women (93.7% in the IFA group vs 93.6% women in the LNS‐PL group at 36 weeks gestation; and 97.0% in the IFA group vs 95.0% in the LNS‐PL group at 6 month postpartum) were categorized with low UI when the World Health Organization cut‐off (UI < 150 μg/L) was used. There were no significant differences between the IFA and LNS‐PL groups in the prevalence of low UI using any of the cut‐offs. However, when restricting analysis to women with high adherence, the LNS‐PL group had a lower prevalence of UI < 50 μg/L (75.9% in the IFA group and 68.9% in the LNS‐PL group; p=0.017) at 36 weeks gestation.

Conclusion

There is a very high prevalence of low UI among pregnant and lactating women in Bangladesh. It is unclear why daily supplementation with 250 μg of iodine via LNS‐PL did not reduce the prevalence of low UI. One possibility is that the iodine in LNS was indeed taken up, but was stored in the thyroid gland (due to a severe iodine deficiency) instead of being excreted in urine, which would imply that UI is not an adequate marker of iodine status in this situation. Our results suggest that there is a need for further research on using other bio‐markers of iodine status and meeting iodine requirements of pregnant and lactating women in Bangladesh and other settings having high prevalence of low UI.

Support or Funding Information

U.S. Agency for International Development's Food and Nutrition Technical Assistance III Project (FANTA), managed by FHI 360