To investigate the relationship between preoperative serum TSH and differentiated thyroid cancer(DTC) in thyroid nodule patients.

From January 2004 to December 2010, data of preoperative serum TSH concentration and pathologic results from 6170 qualified patients underwent thyroid surgery in our department were analyzed retrospectively.

6.3% of patients (389 of 6170) had DTC on final pathology. Mean TSH in the 389 patients with DTC was (2.8 ± 0.3) mU/L vs. (1.1 ± 0.5) mU/L in those 5781 patients with benign diagnoses (P < 0.001). The likelihood of malignancy was 4.9% when TSH was less than 0.34 mU/L vs. 9.1% when 5.50 mU/L or greater(P < 0.001). When the patients were subdivided into TSH ranges, as TSH increased, the likelihood of malignancy on final pathology rose. The mean TSH was (4.5 ± 1.1) mU/L in DTC patients with lateral lymph node metastasis vs. (2.2 ± 0.3) mU/L in DTC patients without lateral lymph node metastasis (P < 0.005).

The likelihood of thyroid cancer increases with higher serum TSH concentration. Higher TSH level is associated with lateral lymph node metastasis.