Serum Unsaturated Free Fatty Acids: A Potential Biomarker Panel for Differentiating Benign Thyroid Diseases from Thyroid Cancer.

BACKGROUND Serum free fatty acids (FFAs) are correlated with pathological status, and change in serum FFA levels may be associated with thyroid diseases. MATERIALS AND METHODS In this study, 664 serum samples from 322 healthy controls, 129 patients with benign thyroid disease (BTD), and 213 patients with thyroid cancer (TC) were collected. Chip-based direct-infusion nanoelectrospray-mass spectrometry was performed to simultaneously quantify six serum FFAs (i.e., C16:1, C18:1, C18:2, C18:3, C20:4, and C22:6.), with the excellent correlation coefficients of > 0.99 and relative standard deviation of <18% for all analysts. The Mann-Whitney U test was used to compare the differences in serum FFA levels between three above-mentioned groups. RESULTS Significant increase in the levels of C16:1, C18:1, C18:2, C18:3, C20:4, and C22:6 in healthy controls relative to TC patients and BTD patients was observed, and the levels of C16:1, C18:2, C20:4, and C22:6 in BTD patients were significantly decreased relative to TC patients. Receiver operating characteristic (ROC) analysis indicated that a combination of C16:1, C18:2, C20:4, and C22:6 has excellent diagnostic performance to differentiate BTD patients from TC patients, with an area under the ROC curve of 0.857, a sensitivity of 76.8%, and a specificity of 83.7%. CONCLUSIONS Change in serum levels of FFAs is closely correlated with thyroid diseases, and a biomarker panel (C16:1, C18:2, C20:4, and C22:6) should be of benefit to differentiate BTD patients from TC patients.