Clinico-Pathological Analysis of Hypothyroidism after Hemithyroidectomy

Koh, Yoon Woo; Lee, Seung Won; Lee, Yong Man; Kim, Hyo Jin; Lee, Jong Dae; Mok, Ji Oh; Byun, Dong Won; Kim, Hee Kyung

Abstract

BACKGROUND AND OBJECTIVES: In hemithyroidectomy, most surgeons don't care about postoperative hypothyroidism because of the remaining functioning contralateral thyroid lobe, but the incidence of hypothyroidism after hemithyroidectomy is reported from 5 to 35%. The purpose of this study was to assess the incidence, natural history, factors contributing to hypothyroidism after hemithyroidectomy.
SUBJECTS AND METHOD
212 consecutive cases of hemithyroidectomized patients diagnosed from Feb. 2001 through Dec. 2004 were retrospectively analyzed. One hundred thirty-six of 212 cases were enrolled in this study after the exclusion criteria applied. The definition of postoperative hypothyroidism was based on serum TSH and free T4 level. The relationship between hypothyroidism and several factors, such as mean age, sex, preoperative free T4, TSH, microsomal antibody, thyroglobulin antibody levels and lymphocytic infiltration of the resected gland, were stastically analyzed.
RESULTS
The fifty eight of 136 patients (42.6%) became biochemical hypothyroidism postoperatively. Among them, 11 patients (8.1%) showed overt hypothyroidism and 47 patients (34.5%) showed subclinical hypothyroidism. In postoperative hypothyroid group, preoperative TSH, microsomal and thyroglobulin Ab levels and lymphocytic infiltration were significantly higher than in postoperative euthyroid group (p<0.05). The odds ratio of preoperative microsomal Ab, thyroglobulin Ab level and lymphocytic infiltration of resected gland was 17.18, 3.01 and 2.26 folds, respectively.
CONCLUSION
In this study, we confirmed that there was unexpectedly high incidence of postoperative hypothyroidism after hemithyroidectomy. We propose that preoperative high TSH level, positive microsomal Ab, thyroglobulin Ab and marked lymphocytic infiltration of resected gland could be predicitive factors of postoperative hypothyroidism after hemithyroidectomy.