Urinary iodine status and thyroid dysfunction: a Bangladesh perspective

Iodine deficiency is endemic in Bangladesh. Compulsory iodization of table salt was introduced since 1993 to prevent and improve thyroid disorders in the country. Urinary iodine status, thyroid function and antithyroid antibodies were studied in 397 newly diagnosed thyroid patients and 94 age-sex matched controls. Among thyroid patients, 96 were hyperthyroid, 185 euthyroid and 116 hypothyroid. Mean and median urinary iodine were higher (p=0.075) in thyroid patients (26.13+/-0.91 and 23.03) than controls (22.65+/-1.47 and 18.59); in hyperthyroid and euthyroid than hypothyroid (p=0.020); in multinodular (28.08+/-2.80 and 26.94) and diffuse (27.35+/-1.19 and 26.71) goitre than uninodular (23.91+/-2.37 and 19.14) and nongoitrous (NG, 21.5+/-2.05 and 18.27) (p=0.098) patients but no sex difference (p=0.466). Antimicrosomal (26.7%) and antithyroglobulin (34%) antibodies were more frequently positive among thyroid patients than controls (6.4% and 12.8% respectively) (p=0.00002 and p=0.00005 respectively). Antibody positivity was higher in diffuse (82/228) and multinodular (20/47) goitre than nongoitrous (20/56) and uninodular (13/66) goitre (p=0.046) as well as in hypothyroid (55.2%) and hyperthyroid (36.5%) than euthyroid (19.5%) patients (P<0.001). Urinary iodine correlated neither with antimicrosomal (thyroid patients: p=0.597 and control: p=0.112) nor with antithyroglobulin (thyroid patients: p=0.388 and control: p=0.195) antibody. Thyroid autoimmunity and dysfunction seems common; and interaction of salt iodization with iodine status and thyroid disorders may be important in Bangladesh.