Epidemiological survey of the status of iodine nutrition and thyroid diseases in Guangxi, China

Objective: To survey the status of iodine nutrition and the prevalence of thyroid diseases in Guangxi, China, and to explore the risk factors for positive thyroid antibody.

Methods: We used the multistage stratified cluster random sampling method to select a total of 2488 subjects from an urban and a rural location. All the subjects completed a questionnaire survey, blood and urine samples were also collected, and B-mode thyroid ultrasound was used to determine thyroid function and detect thyroid antibodies.

Results: 1) The median level of urinary iodine was 148.53 μg/L in school-age children in Guangxi, China. 2) The prevalence rates for thyroid diseases were as follows: hyperthyroidism, 0.89 %; subclinical hyperthyroidism, 1.05 %; hypothyroidism, 0.69 %; and subclinical hypothyroidism, 8.87 %. The rates of thyroid antibody positivity were as follows: thyroid peroxidase antibody (TPOAb), 13.60 %; thyroglobulin antibody (TGAb), 13.60 %; thyroid antibodies, 18.2 %; and thyroid nodules, 16.94 %. 3) The rate of TPOAb positivity was significantly higher in women aged 18-29, 30-39, 40-49, or 60-69 years than in men in the same age groups (P < 0.05), and the TGAb positivity rate was significantly higher in women than in men of the same age group (P < 0.05). 4) The rate of thyroid antibody positivity was significantly higher in individuals with iodine deficiency than in individuals with adequate iodine (21.6 % vs 18.4 %) or excess iodine (21.6 % vs 15.5 %) (both P < 0.05). 5) The female sex and a family history of thyroid diseases were the major risk factors for thyroid antibody positivity (odds ratio [OR] 3.010, P <0.05; OR 2.486, P <0.05).

Conclusion: The overall level of iodine is adequate in Guangxi, China; this level should be maintained to prevent the thyroid diseases related with iodine deficiency or excess of iodine. Female sex and a family history of thyroid diseases are independent risk factors for thyroid antibody positivity.