TSH suppression in the management of thyroid nodules and thyroid cancer

Clinical and experimental data concerning TSH suppression, by giving exogenous thyroid hormone, in patients with goiter and in patients with thyroid cancer show a beneficial effect. In the goiter patients, TSH suppressive therapy seems most effective in young patients with diffuse or newly discovered goiters, in hypothyroid patients, and in patients with chronic lymphocytic thyroiditis or compensatory thyroid hypertrophy after partial thyroidectomy. With TSH suppressive therapy about 2/3 of thyroid nodules become smaller, but only about 5% to 10% disappear. In patients with differentiated thyroid cancer (papillary, mixed papillary‐follicular, and follicular), tumor recurrence, tumor progression, and long‐term survival all seem to be influenced favorably by TSH suppressive therapy. Experimental investigations demonstrate that both benign thyroid adenomas and differentiated thyroid carcinomas have TSH receptors situated on the plasma membranes. These TSH receptors appear to be coupled to the activation of adenylate cyclase in a one‐to‐one relationship. Experimental and clinical studies strongly support the use of thyroid hormone both for the treatment of patients after thyroidectomy for thyroid cancer and as prophylaxis to prevent the development of thyroid cancer in high‐risk irradiated patients. The dose of thyroxine recommended for adequate TSH suppression is the lowest dose of thyroxine that will completely block the TSH response to TRH (usually 0.2 to 0.25 mg) .