Background: Patients with thyroid nodules may be complicated by hypothyroidism. However, effective means to predict thyroid-stimulating hormone (TSH) elevation in patients with thyroid nodules are currently lacking. Therefore, the research team recruited some patients with thyroid nodules to explore the relationship between TSH, environmental iodine, and fluoride and the development of thyroid nodules, and to draw a Nomogram in order to provide guidance for predicting hypothyroidism in patients with thyroid nodules.
Methods: The subjects were from 313 patients with thyroid nodules in different areas of iodine and fluoride, with 71 men and 242 women. The content of TSH in serum of thyroid nodule patients was determined by electrochemical luminescence method. The iodine content in drinking water and urine was determined by arsenic-cerium catalytic spectrophotometry. Fluoride in drinking water and urine was determined by fluoride ion selective electrode method. Univariate analysis, Lasso regression analysis and multiple factor Logistic regression analysis were used to screen the variables included in the Nomogram model. And the corresponding Nomogram model was constructed. ROC curve was drawn and repeated Bootstrap self-sampling method was used to test model differentiation.
Results: There were 53 patients with elevated serum TSH and 256 patients with normal thyroid nodule. Multivariate logistic regression analysis shows that urine iodine（Odds Ratio[OR]=1.001, 95% confidence interval [95%CI]:1.001～1.002, P=0.01） and gender (OR=3.328, 95% CI:1.256～8.819, P=0.079) are independent risk factors raised by serum TSH. And drinking water fluoride（OR=1.990, 95% CI:0.924～4.289, P=0.079）is a critical factor. Based on these risk factors, the predictive model and nomogram of serum TSH elevation in patients with thyroid nodule were constructed. The area under the ROC curve was 0.678 (P<0.001), confirming Nomogram's predictive potential. The calibration diagram of the Nomogram prediction model shows that the predicted values are in good agreement with the observed values.
Conclusion: Gender, urine iodine and drinking water fluoride of thyroid nodules are independent influencing factors for the rise of serum TSH. The Nomogram can become a predictive accuracy and differentiation.