Objective: To identify the incidence and possible risk factors for the development of hypothyroidism following hemithyroidectomy and to determine a simple protocol for the post-op monitoring of thyroid function.
Design: Prospective study.
Setting: Tertiary Referral Centre.
Patients: Eighty-two consecutive patients who underwent hemi-thyroidectomy between May 2003 and May 2005 were included. The clinical and pathological factors were obtained and statistically analysed.
Results: Eighteen per cent of patients became hypothyroid post-operatively. Multivariate analysis demonstrated that risk factors for hypothyroidism following hemithyroidectomy included a pre-operative [TSH] >1.6 microIU/L [P = 0.008, hazard ratio (HR) 14, 95% confidence interval (CI) 2-54] and lymphocytic infiltration graded 3+ or more (P < 0.001, HR 42, 95% CI, 8-195%). There was no relationship between age, sex or weight of resected tissue and the risk of hypothyroidism.
Conclusion: Patients with raised pre-operative [TSH] or with lymphocytic infiltration of their thyroid specimen should undergo regular testing of thyroid function within the first year of surgery. In all other patients, thyroid function at 12 months is sufficient.