Thyroid Nodules Are More Prevalent in Subjects with Colon Polyps, Independent of Insulin Resistance

Colorectal polyps and thyroid nodules are common disorders linked to hyperinsulinemia and metabolic syndrome (Mets). The direct association between these two diseases is not clear. We aimed to analyze the prevalence of thyroid nodules in subjects with and without colorectal polyps. The secondary aim was to establish the prevalence of Mets and its parameters in both disorders and to determine if insulin resistance and hyperinsulinemia are common underlying pathophysiological mechanisms.

One hundred and five subjects with colorectal polyps (71 males, 34 females) and 68 controls (28 males, 40 females) were enrolled. The parameters of Mets together with TSH, insulin, low-density lipoprotein cholesterol, and homeostasis model for assessment of insulin resistance levels were calculated. We performed thyroid ultrasonography in all participants.

The prevalence of Mets was similar in the colorectal polyp and control groups (37.1 vs. 37.3%, p = 0.982). The prevalence of Mets was nonsignificantly higher in subjects with a documented thyroid nodule compared to subjects without a thyroid nodule (43.0 vs. 32.6%, p = 0.205). The prevalence of thyroid nodules in subjects with colorectal polyps was significantly higher than in subjects without polyps (52.9 vs. 35.3%, p = 0.017). Compared to subjects with no colorectal polyps, we established a significant increase in the odds of having thyroid nodules (OR 2.05; 95% CI: 1.097-3.860, p = 0.017). The presence of colorectal polyps and age in the adjusted model were established to be independent risk factors for having thyroid nodules (p = 0.025 and p = 0.007, respectively).

These results may support the presence of other common mechanisms in the development of these two pathologies other than insulin resistance and hyperinsulinemia.