Is standard 555 MBq 131I-therapy of hyperthyroidism ablative?

The effect of a standard 555 MBq 131I dose in ablating the thyroid gland was investigated in 116 consecutive hyperthyroid patients. Fifty-one had Graves' disease, 50 a multinodular toxic goitre and 15 had a solitary toxic nodule. 555 MBq 131I was given regardless of size or type of the gland and severity of the disease. Within one year after this dose hypothyroidism was induced in 41% of patients with Graves' disease, but in only 13% with a solitary toxic adenoma, and 6% with a multinodular gland. Forty-eight percent of the patients with a multinodular gland, 33% with Graves' disease and 13% with a solitary toxic nodule were still hyperthyroid. Since this so called ablative treatment only accomplishes hypothyroidism in 26/116 (23%) of our patients and results seem unpredictable 131I treatment adjusted according to gland size and type aiming at achieving euthyroidism could be contemplated.