Poster Topical Area: Biomarkers

Location: Auditorium

Poster Board Number: 142

P02-008 - Dried blood spot thyroglobulin is a promising new biomarker of iodine excess in pregnant women

Sunday, Jun 10
8:00 AM – 6:00 PM

Objectives:

We have previously shown that a field-friendly dried blood spot (DBS) thyroglobulin (Tg) assay can be used to detect low iodine intakes in pregnant women (PW). However, iodine programs need to monitor not only for deficiency, but also for excessive iodine intakes, as excess intakes increase risk for thyroid disorders. Therefore, the aim of this multicentre study was to assess DBS-Tg as a potential functional biomarker of more-than-adequate to excessive iodine intakes during pregnancy.




Method:


In cross-sectional studies in 9 countries, we compared DBS-Tg in PW with a sufficient iodine intake (5 countries; urinary iodine concentration (UIC) 150-250 μg/L) to DBS-Tg in PW with more-than-adequate iodine intake (4 countries; UIC 250-500 μg/L) from all trimesters. From each women, a spot urine sample and a DBS sample were collected. UIC was analysed using the Sandell-Kolthoff method and DBS-Tg using an in-house, low-cost sandwich enzyme linked immunosorbent assay. The data were analyzed continuously and as pooled estimates comparing the sufficient to the more-than-adequate sites.




Results:


Median (95% confidence interval (CI)) UIC and Tg of the sufficient group were 182.79 (172.86-192.34) μg/L and 11.54 (10.77-12.35) μg/L, respectively, and in the more-than-adequate group were 350.34 (333.45-366.82) μg/L and 20.66 (19.61-21.97) μg/L, respectively, (for both, p<0.0001). A bubble chart of median Tg versus median UIC, clustered by country, is shown in Figure 1; a second-order polynomial trend line is included and sample size per country is reflected by bubble size.




Conclusions:


In pregnant women, DBS-Tg increases with increasing UIC, and is higher in women with more-than-adequate iodine intakes than in those with sufficient intakes. Thus, DBS-Tg may be a promising new biomarker of more-than-adequate to excessive iodine intakes in pregnant women that can be used in program monitoring.



Funding Source:

UNICEF micronutrient section, New York City, USA.
Swiss State Secretariat for Education, Research and Innovation (SERI), Bern, Switzerland.
ETH Zurich, Switzerland.



Bubble chart of median urinary iodine concentration (UIC) versus median dried blood spot (DBS) thyroglobulin (Tg), clustered by country, including a second-order polynomial trend line

CoAuthors: Jessica Farebrother – ETH Zurich, Switzerland; Nicholas Hutchings – Yerevan State Medical University, Armenia; Anselimo Makokha – Jomo Kenyatta University of Agriculture and Technology, Kenya; Robizon Tsiklauri – National Association of Nutritionists, Georgia; Maria Andersson – ETH Zurich, Switzerland; Michael Zimmermann – ETH Zurich, Switzerland

Sandra Hunziker

Doctoral Student
ETH Zurich, Switzerland
Zurich, Zurich, Switzerland