Association of serum thyrotropin level with papillary thyroid microcarcinoma

Objective To study whether preoperative serum thyrotropin （TSH） concentration can be used for risk prediction of papillary thyroid microcarcinoma （ PTMC ）. Methods The cohort of this retrospective study consisted of 1 707 patients who underwent surgery on thyroid nodules at Chinese PLA General Hospital from October 1999 to February 2011. 37.32% （ n = 637） of these patients suffered from differentiated thyroid cancer （ DTC ）, and 14.18 % （ n = 242） of patients with DTC suffered from PTMC. Results （ 1 ） The mean TSH level in patients with DTC was significantly higher than that in patients with benign thyroid nodules [ （ 1.99（1.25-3.19） vs 1. 48 （0.85-2.32） mU/L, P〈0. 01 1- DTC with diameter greater than 10 mm had higher serum TSH level compared with that in benign thyroid nodules [ 2.04（ 1.26-3.36 ） vs 1.45 （ 0.83-2.30 ）, P〈0.01 ]. Serum TSH level was not significantly raised in cases where-as the diameter of tumor was 10 mm or less. （ 2 ） With the increasing level of TSH, the prevalence of DTC and tumours with diameter greater than 10 mm rose significantly, but the increasing trend was not significant in PTMC. （ 3 ） Raised TSH level was an independent risk factor of DTC based on Binary logistic regression. Conclusions Serum TSH is an independent risk predictor of DTC, it is an independent risk predictor of the diameter of DTC greater than 10 mm, but it is not a good risk predictor in PTMC. Key words: Differentiated thyroid cancer;  Ppapillary thyroid microcarcinoma;  Thyrotropin