Preoperative subclinical hypothyroidism in patients with papillary thyroid carcinoma

Objective

To assess the effect of preoperative subclinical hypothyroidism on prognosis and on the tumour's clinicopathological features at initial diagnosis of papillary thyroid carcinoma (PTC).

Materials and methods

328 patients who underwent surgery for PTC between January 2001 and December 2006 were enrolled in this study. Of these, we compared 35 patients with preoperative subclinical hypothyroidism with 257 patients who were euthyroid before the operation, with respect to clinicopathological characteristics and prognosis.

Results

No significant differences were observed in tumour size, extrathyroidal extension, and multifocality between subclinical hypothyroidism and euthyroid patients. Patients with subclinical hypothyroidism had a considerably lower percentage of lymph node metastasis than did euthyroid patients (8.6% vs. 21.8%, p = 0.068). Although preoperative subclinical hypothyroidism decreased the risk of lymph node metastasis at 0.313 of odds ratio in the multivariate analysis, its significance was not verified (95% confidence internal, 0.089–1.092; p = 0.068). Patients with preoperative subclinical hypothyroidism tended to have a better prognosis than did preoperative euthyroid patients, for both recurrence (2.9% vs. 14.0%, p = 0.099) and 7-year disease-free survival (97.1% vs. 87.8%, p = 0.079), during the 82-month mean follow-up period. However, even as thyroid-stimulating hormone (TSH) concentration increased, there were no consistent relationships observed between the TSH levels and the prognostic parameters.

Conclusion

We could find neither a consistent positive nor a negative linear relationship between TSH levels and several prognostic parameters, indicating that subclinical hypothyroidism with elevated TSH is not an independent predictor of tumour aggressiveness and poor prognosis in PTC.