Changes in thyroid function and immunological parameters long after subtotal thyroidectomy for Graves' disease.

OBJECTIVE

To find out whether subtotal thyroidectomy results in long term stable functional and immunological remission in patients with Graves' disease.

DESIGN

Retrospective study.

SETTING

Teaching hospital, Japan.

SUBJECTS

176 patients who underwent subtotal thyroidectomy for Graves' disease, 1970-79.

INTERVENTION

Follow up surveys in 1984 and 1992.

MAIN OUTCOME MEASURES

Changes in thyroid function, antibody titres, and lymphocyte subsets.

RESULTS

29/79 patients (39%) who were euthyroid in 1984 had evidence of thyroid dysfunction in 1992. Of the 8 patients with latent hypothyroidism in 1984, 3 (38%) had become euthyroid by 1992, and none required treatment. Of the 29 patients who were hypothyroid in 1984, 5 had latent hypothyroidism and 1 was euthyroid in 1992, and of the 18 patients with recurrent hyperthyroidism in 1984, 1 had become euthyroid by 1992. The number of positive titres to TSH-binding inhibitory immunoglobulin was significantly higher in the recurrence group (31/36, 86%) compared with the hypothyroid (7/26, 27%), latent hypothyroidism (8/37, 22%), and euthyroid (22/77, 29%) groups (p < 0.01). There were also significant differences in the mean (SD) number of Leu HLA DR subsets between the control (17 (3), n = 18) and recurrence (21 (6), n = 38), hypothyroid (22 (6), n = 35), latent hypothyroidism (22 (6), n = 22), and euthyroid (22 (9), n = 64) groups (p < 0.002). There were no differences in the number of T cell subsets among the groups.

CONCLUSION

Treatment of Graves' disease by subtotal thyroidectomy does not necessarily result in stable late functional or immunological remission. Long term follow up of such patients may be necessary.