Acta clinica Croatica, Vol. 54. No. 4., 2015.
Original scientific paper
Sufficient iodine intake in schoolchildren from the Zagreb area: assessment with dried blood spot thyroglobulin as a new functional biomarker for iodine deficiency
Tomislav Jukić
orcid.org/0000-0001-5631-164X
; Clinical Department of Oncology and Nuclear Medicine, Sestre milosrdnice University Hospital Center, Zagreb, Croatia; School of Medicine, University of Zagreb, Zagreb, Croatia; School of Medicine, Josip Juraj Strossmayer University, Osijek, Croatia
Michael Bruce Zimmermann
; Human Nutrition Laboratory and the Secretariat of the International Council for the Control of Iodine Deficiency Disorders (ICCIDD) Global Network (M.B.Z., I.A., M.A.), Swiss Federal Institute of Technology (ETH), Zurich, Switzerland
Roko Granić
; Clinical Department of Oncology and Nuclear Medicine, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
Marin Prpić
; Clinical Department of Oncology and Nuclear Medicine, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
Dražena Krilić
; Clinical Department of Oncology and Nuclear Medicine, Sestre milosrdnice University Hospital Center, Zagreb, Croatia
Vesna Jureša
; School of Medicine, University of Zagreb, Zagreb, Croatia; Andrija Štampar School of Public Health, Zagreb, Croatia
Marijan Katalenić
; Croatian Institute of Public Health, Zagreb, Croatia
Zvonko Kusić
; Clinical Department of Oncology and Nuclear Medicine, Sestre milosrdnice University Hospital Center, Zagreb, Croatia; School of Medicine, University of Zagreb, Zagreb, Croatia
Abstract
Current methods for assessment of iodine intake in a population comprise measurements of urinary iodine concentration (UIC), thyroid volume by ultrasound (US-Tvol), and newborn TSH. Serum or dried blood spot thyroglobulin (DBS-Tg) is a new promising functional
iodine status biomarker in children. In 1996, a new act on universal salt iodination was introduced in Croatia with 25 mg of potassium iodide per kg of salt. In 2002, Croatia finally reached iodine sufficiency. However, in 2009, median UIC in 101 schoolchildren from Zagreb, the capital of Croatia, was 288 μg/L, posing to be excessive. The aim of the study was to assess iodine intake in schoolchildren from the Zagreb area and to evaluate the value of DBS-Tg in schoolchildren as a new functional biomarker of iodine deficiency (and iodine excess). The study was part of a large international study in
6- to 12-year-old children supported by UNICEF, the Swiss Federal Institute of Technology (ETH Zurich) and the International Council for the Control of Iodine Deficiency Disorders (ICCIDD). According to international study results, the median cut-off Tg <13 μg/L and/or <3% Tg values >40 µg/L indicate iodine sufficiency. The study included 159 schoolchildren (median age 9.1±1.4 years) from Zagreb and a nearby small town of Jastrebarsko with measurements of UIC, US-Tvol, DBSTg, T4, TSH and iodine content in salt from households of schoolchildren (KI/kg of salt). Overall median UIC was 205 µg/L (range 1-505 µg/L). Thyroid volumes in schoolchildren measured by US were within the normal range according to reference values. Median DBS-Tg in schoolchildren was 12.1 μg/L with 3% of Tg values >40µg/L. High Tg values were in the UIC range <50 µg/L and >300 µg/L (U-shaped curve of Tg plotted against UIC). All children were euthyroid with geometric mean TSH 0.7±0.3 mU/L and arithmetic mean T4 62±12.5 nmol/L. The mean KI content per kg of salt was 24.9±3.1 mg/kg (range 19-36 mg/kg). Study results indicated iodine sufficiency in schoolchildren from the Zagreb area. Thyroglobulin proved to be a sensitive indicator of both iodine deficiency and iodine excess in children. Iodine content in salt from households of schoolchildren was in good compliance with the Croatian act (20-30 ,mg KI/kg of salt).
Keywords
Iodine – urine; Iodine – analysis; Thyroglobulin – analysis; Thyroid gland – function tests; Thyroid gland – ultrasonography; Schoolchildren
Hrčak ID:
154951
URI
Publication date:
1.12.2015.
Visits: 2.271 *