Urinary iodine and thyroid status of New Zealand residents

• Published in: European journal of clinical nutrition 2001-05, Vol.55 (5), p.387-392
• Main Authors: THOMSON, C. D, WOODRUFFE, S, COLLS, A. J, JOSEPH, J, DOYLE, T. C
• Format: Article
• Language: English
• Subjects: Adolescent; Adult; Biological and medical sciences; Biomarkers; Clinical nutrition; Creatinine; Excretion; Female; Functional investigation of endocrine glands and genital system; Goiter - epidemiology; Health aspects; Health risk assessment; Health Status; Health Status Indicators; Hormones; Humans; Investigative techniques, diagnostic techniques (general aspects); Iodides; Iodides - urine; Iodine; Iodine - administration & dosage; Iodine - deficiency; Iodine - pharmacokinetics; Iodine in the body; Male; Medical sciences; Middle Aged; Multiple regression analysis; New Zealand - epidemiology; Nutrient deficiency; Nutrition; Properties; Regression Analysis; Soil; Soils; Thyroglobulin; Thyroglobulin - blood; Thyroid; Thyroid gland; Thyroid Gland - diagnostic imaging; Thyroid hormones; Thyroid Hormones - blood; Thyroid-stimulating hormone; Thyrotropin - blood; Thyroxine; Thyroxine - blood; Ultrasonography
• ISSN: 0954-3007; 1476-5640
• DOI: 10.1038/sj.ejcn.1601170

The aim of this project was to assess the clinical significance of our low iodine excretions in terms of thyroid hormone status and thyroid volume in an adult population in a low soil iodine area of the South Island of New Zealand. Two-hundred and thirty-three residents of Otago, New Zealand collected two 24 h urine samples for assessment of iodine status. Thyroid status was determined from serum total T(4), TSH and thyroglobulin, and thyroid volumes. Relationships between urinary iodide excretion and measures of thyroid status were determined and subjects were allocated to one of three groups according to low, medium and high iodide excretion, for comparison of thyroid hormones and thyroid volumes. Significant correlations were found for relationships between measures of urinary iodide excretion and thyroid volume and thyroglobulin. Multiple regression analysis of data for subjects divided into three groups according to 24 h urinary iodide excretion (90 microg iodide/day) or iodide/creatinine ratio (60 microg/g Cr) showed significant differences in thyroid volume (P=0.029; P=0.035, respectively) and thyroglobulin (P=0.019; P=0.005, respectively) among the groups. The results of this study confirm the low iodide excretions of Otago residents, and indicate that the fall in iodine status is being reflected in clinical measures of thyroid status, including enlarged thyroid glands and elevated thyroglobulin. Our observations suggest the possible re-emergence of mild iodine deficiency and goitres in New Zealand. This situation is likely to worsen should iodine intakes continue to fall and continued monitoring of the situation is imperative.