Detection of preoperative serum trace elements in thyroid tumors

The incidence of thyroid tumors has increased sharply worldwide. Some trace elements (Ca, Mg, Fe, Mn, Co, Cu, Zn, Se) are essential for maintaining the hormonal balance of the thyroid gland, while other toxic elements (Ni, As, Pt, Mo, Cd, Ti, Pb) may cause various thyroid diseases. Our study aims to investigate whether serum trace elements are related to the occurrence of thyroid tumors.

Preoperative serum samples were collected from patients with thyroid tumors, including 54 benign thyroid tumor cases and 76 papillary thyroid carcinoma (PTC) cases. Fifty-one healthy individuals who underwent routine physical examinations were selected as the control group. Serum concentrations of 15 trace elements (Ca, Mg, Fe, Mn, Co, Cu, Zn, Se, Ni, As, Pt, Mo, Cd, Ti, Pb) were measured by inductively coupled plasma-mass spectrometry (ICP-MS). Meanwhile, clinical biochemical and thyroid function indicators were detected. Serum levels among the three groups were compared using SPSS 22.0 software.

Among the three groups, there was no significant difference in serum biochemical and thyroid function indicators. Among the 15 trace elements, preoperative serum levels of Ca, Mg, Cu, Zn, Se, and Mo in the benign thyroid tumor and PTC groups were markedly higher than those in the control group (P<0.05). However, no significant difference in these 6 trace elements was observed between the benign thyroid tumor and PTC groups. Regarding the remaining 9 trace elements, there was no significant difference among the three groups. Multivariable analyses indicated that only high serum Cu [odds ratio (OR), 1.004; 95% confidence interval (CI): 1.002-1.008; P=0.02] and high serum Zn (OR, 1.009; 95% CI: 1.005-1.013; P<0.001) levels were independent risk factors for thyroid tumors. The receiver operating characteristic (ROC) curve analysis showed that serum Cu and Zn had an area under the curve (AUC) of 0.720 (sensitivity 63.1% and specificity 76.5%; P<0.001) and 0.781 (sensitivity 63.1% and specificity 88.2%; P<0.001) for distinguishing between thyroid tumors and the control group, respectively. In addition, serum Cu levels in thyroglobulin antibody (TG-Ab)-positive patients were obviously higher compared with those in TG-Ab-negative patients.

Our study indicates that the concentrations of preoperative serum trace elements (Ca, Mg, Cu, Zn, Se, and Mo) may be correlated with thyroid tumors, but they were not associated with the benign or malignant nature of thyroid tumors. Serum Zn may serve as a useful adjunct for the diagnosis of thyroid tumors. Additionally, a high serum Cu concentration is positively correlated with the presence of thyroid autoantibodies.