Effect of oral iodized oil on thyroid size and thyroid hormone metabolism in children with concurrent selenium and iodine deficiency.

OBJECTIVES: To determine the efficacy of oral iodized oil in goitrous children who are both selenium (Se) and iodine deficient; to investigate if Se status modifies the response of iodine deficient, goitrous children to oral supplementation with iodized oil. DESIGN: A longitudinal intervention trial. SETTING: Two rural villages in the western Côte d'Ivoire. SUBJECTS: 51 goitrous non-anemic schoolchildren with both iodine and Se deficiency. INTERVENTION: Each child received an oral dose of 0.4 ml iodized poppyseed oil containing 200 mg of iodine. They were followed for 1 y with measurements of urinary iodine (UI), thyrotropin (TSH), thyroxine (T4), and thyroid volume by ultrasound. RESULTS: At baseline all children were goitrous and Se deficient; median UI was 29 microg/l and mean serum Se (s.d.) was 14.8 (10.7) microg/l. After receiving iodized oil, thyroid volume decreased significantly vs baseline at 10, 15, 30 and 50 weeks (P<0.001). At 50 weeks mean percentage change in thyroid volume from baseline was-46.6% and only five children remained goitrous. Median TSH values at 5, 10, 15, 30 and 50 weeks were reduced significantly (P<0.001) compared to baseline. Among individual children the severity of Se deficiency predicted the degree of response to iodized oil. Baseline serum Se and percentage change in thyroid volume from baseline at 50 weeks were strongly correlated (r2=0.554). Baseline Se and percentage decrease in TSH from baseline at 30 weeks were also well-correlated (r2=0.467). CONCLUSION: Although more severe Se deficiency partially blunts the thyroid response to iodine supplementation, oral iodized oil is an effective method for iodine repletion in goitrous children who are Se deficient. SPONSORSHIP: The Swiss Federal Institute of Technology, Zürich, the Foundation for Micronutrients in Medicine, Rapperswil, Switzerland, and the Thrasher Research Fund, Salt Lake City, USA.