COULD SERUM TSH LEVELS PREDICT MALIGNANCY IN THYROID NODULES WITH INDETERMINATE CYTOLOGY?

Objectives: To evaluate the serum thyreotropin (TSH) levels as a possible predictor of malignancy in thyroid nodules with indeterminate cytology. Methods: We reviewed the medical records of patients who had ultrasound- guided FNA of thyroid nodules at our Department between September 2014 and February 2018. Only patients with indeterminate cytology and TSH values within the normal range obtained one month before FNA were enrolled. All patients had been submitted to hemi or thyroidectomy in our Institute. Results: Histologic evaluation revealed malignancy in 74/378 (19.6%) nodules. The rate of cancer was significantly lower in TIR 3A (9.8%) than TIR 3B lesions (27.4%), p<0.0001. Patients with malignancy evidenced higher serum TSH levels than those with histological proven benign nodules (3.03±1.16 vs. 2.37±1.19 mIU/L, p<0.001). To better analyze the role of serum TSH as a predictor of thyroid cancer, we subdivided the sample into 4 quartiles of similar size according to patients’ TSH values. The prevalence of malignancy was 12.2% for the first quartile and 50.0% for the last quartile. The ROC curve analysis indicated that a TSH value of ≥2.7 mIU/L identified patients with malignancy with a sensitivity of 61% and a specificity of 65%. Conclusions: Higher TSH levels are associated with an increasing risk of malignancy in patients affected by thyroid nodules with indeterminate cytology. The use of TSH can represent an easy adjunctive diagnostic test for decision-making in patients with indeterminate cytological findings.