Despite the high risk of bias of many of the included studies , the results suggested that urinary iodine , thyroglobin , serum thyroxine , and thyroid-stimulating hormone are useful biomarkers of iodine status , at least in some groups .
BACKGROUND Biomarkers of iodine status are required to study iodine deficiency disorders in different parts of the world and to evaluate the effects of fortification strategies .
OBJECTIVE The objective was to assess the usefulness of biomarkers of iodine status in humans by systematic ally review ing intervention studies that altered iodine status .
Assessment of iodine status using dried blood spot thyroglobulin: development of reference material and establishment of an international reference range in iodine-sufficient children.
CONTEXT Thyroglobulin ( Tg ) may be a valuable indicator of improving thyroid function in children after salt iodization . A recently developed Tg assay for use on dried whole blood spots ( DBS ) makes sampling practical , even in remote areas . OBJECTIVE The study aim was to develop a reference st and ard for DBS-Tg , establish an international reference range for DBS-Tg in iodine-sufficient children , and test the st and ardized DBS-Tg assay in an intervention trial . DESIGN , PARTICIPANTS , AND INTERVENTIONS Serum Tg reference material of the European Community Bureau of Reference ( CRM-457 ) was adapted for DBS and its stability tested over 1 yr . DBS-Tg was determined in an international sample of 5- to 14-yr-old children ( n = 700 ) who were euthyroid , anti-Tg antibody negative , and residing in areas of long-term iodine sufficiency . In a 10-month trial in iodine-deficient children , DBS-Tg and other indicators of iodine status were measured before and after introduction of iodized salt . RESULTS Stability of the CRM-457 Tg reference st and ard on DBS over 1 yr of storage at -20 and -50 C was acceptable . In the international sample of children , the third and 97th percentiles of DBS-Tg were 4 and 40 microg/liter , respectively . In the intervention , before introduction of iodized salt , median DBS-Tg was 49 microg/liter , and more than two thirds of children had DBS-Tg values greater than 40 microg/liter . After 5 and 10 months of iodized salt use , median DBS-Tg decreased to 13 and 8 microg/liter , respectively , and only 7 and 3 % of children , respectively , had values greater than 40 microg/liter . DBS-Tg correlated well at baseline and 5 months with urinary iodine and thyroid volume . CONCLUSIONS The availability of reference material and an international reference range facilitates the use of DBS-Tg for monitoring of iodine nutrition in school-age children
Despite the high risk of bias of many of the included studies , the results suggested that urinary iodine , thyroglobin , serum thyroxine , and thyroid-stimulating hormone are useful biomarkers of iodine status , at least in some groups .
BACKGROUND Biomarkers of iodine status are required to study iodine deficiency disorders in different parts of the world and to evaluate the effects of fortification strategies .
OBJECTIVE The objective was to assess the usefulness of biomarkers of iodine status in humans by systematic ally review ing intervention studies that altered iodine status .