The present work showed nodular goiter lesions to contain significantly less iodine than normal thyroid tissue, and iodine content was found to be negatively correlated with TSHr expression, suggesting that iodine in follicular lumen inhibits expression of TSHr and low iodine status in the follicular lumen of nodular goiter promotes upregulation of TSHR expression. The gene discussed is TSHR; the disease is nodular goiter.