Association of antithyroglobulin antibody with iodine nutrition and thyroid dysfunction in Nepalese children

Abstract

Background: Aberrant iodine intake and thyroid autoimmunity affect thyroid function. Deficiencies of iodine including thyroid disorders have serious impact on child physical and mental development. This study was conducted to investigate iodine nutrition, thyroid function and thyroid autoimmunity in the Nepalese children, and explore the association of thyroidal autoimmunity with iodine nutrition and thyroid dysfunction. Methods: Five schools from Udayapur district of eastern Nepal were selected for the study. A total of 213 school children aged 6-12 years were enrolled, and anthropometric data, urine samples and blood samples were collected. Urinary iodine concentration (UIC), free triiodothyronine (fT3), free thyroxine (fT4), thyroid stimulating hormone (TSH), and antithyroglobulin antibody (TgAb) was measured. Independent T test, Man-Whitney test, Chi-square test and Fisher's Exact test were used for testing statistical significance. Spearman's correlation analysis was done to find association between variables. Results: The median UIC with IQR, mean ± SD fT3, mean ± SD fT4, median TSH and TgAb with IQR was 150.0 μg/L (102.8; 204.0), 2.49 ± 0.83 pg/ml, 1.33 ± 0.42 ng/dl, 2.49 mIU/L (1.58; 4.29), and 21.40 IU/ml (15.54; 31.20) respectively. Elvated TgAb (≥30 IU/ml, thyroid autoimmune condition) was seen in 25.8% (n = 55) children. UIC was less than 100 μg/L in 17.4% (n = 37) of the children. Subclinical hypothyroidism, overt hypothyroidism and sublinical hyperthyroidism was seen in 1.4% (n = 3), 3.3% (n = 7) and 3.8% (n = 8) children respectively. A strong association of TgAb with UIC (r = - 0.210, p = 0.002) and thyroid hormones; fT3 (r = - 0.160, p = 0.019), fT4 (r = - 0.275, p < 0.001), and TSH (r = 0.296, p < 0.001) was seen. The relative risk for thyroid autoimmunity in children with UIC less than 100 μg/L was 1.784 (95% CI: 1.108-2.871, p = 0.024). Similarly, children with thyroid autoimmunity had higher relative risk [7.469 (95% CI: 2.790-19.995, p < 0.001)] for thyroid dysfunction. Conclusions: School children of eastern Nepal have adequate iodine nutrition. Thyroid autoimmunity is very common, while thyroid dysfunction is sparse in children. An association of thyroid autoimmunity with iodine nutrition and thyroid dysfunction was seen in children.