Relationship between Serum Thyrotropin Level and Post-Operative Goitre Recurrence

Following partial thyroid resection for non-toxic nodular goitre, 309 euthyroid patients were allocated to thyroxine usage and thyrotropin (TSH) level. Thyroid hormones and TSH were evaluated post-operatively every year. Recurrence were investigated with physical examinations, scintigraphy and ultrasonography, and diagnosed with two or three of those tests. We determined the effect of thyroxine and TSH level on the incidence of post-operative goitre recurrence. The incidence of recurrence was found 33.3% in 39 patients regularly taking 0.15 mg/day or more thyroxine, 47.4% in 57 patients regularly taking 0.10 mg/day thyroxine, 66.3% in 83 patients taking thyroxine, irregularly, and 78.5% in 130 patients who did not take any thyroxine. The recurrence was 58.6% in patients with TSH level less than 1 IU/ml, 66.9% in patients with TSH level between 1 to 5 IU/ml, and 62.5% in patients with TSH level more than 5 IU/ml. It was seen that the incidence of recurrence was not diminishing with suppression of TSH level while it was perceptively reduced in the patients who used thyroxine regularly at 0.15 mg/day or more doses as compared to those who use irregularly or not all. We observed that there is no strong relation between post-operative recurrence rate and TSH level. We believe that the thyroxine is necessary in order to prevent post-operative goitre recurrence, but the mechanism of prevention with thyroxine usage may not be TSH suppression.