borderline significantP = 0.082
Multivariate logistic regression analysis established vitamin D as an independent protective factor against malignant thyroid nodules (OR = 0.542, 95% CI: 0.354–0.852, P = 0.008), while IL-17 demonstrated a borderline significant association as a risk factor (OR = 1.415, 95% CI: 0.957–2.094, P = 0.082).