Thyrotoxicosis aggravated by iodinated contrast medium: a case report.

Thyrotoxicosis may be aggravated by the administration of either iodinated contrast medium or inorganic iodide. A case of subclinical hyperthyroidism aggravated by iodinated contrast medium is presented here. The patient had received right subtotal lobectomy of the thyroid gland for thyroid cyst in 1969. She had been well until February 1981, when she was found by 131I thyroid scan to have left nodular goiter. Thyroid function was in euthyroid state. Progressive enlargement of the left nodular goiter was noted in October 1987, with thyroid function still in the euthyroid state. Therefore, suppression therapy with L-thyroxine (Eltroxin 0.1 mg per day) was given for eight months until July 1988. The patient was lost to follow-up thereafter until she was admitted to the endocrine ward of the Veterans General Hospital-Taipei in August 1992 because of a progressively enlarged goiter associated with body weight loss. Serum T3 (127 ng/dl) and T4 (11.36 micrograms/dl) were within normal range, but TSH (0.06 microU/ml) was very low. The patient had exacerbated symptoms of hyperthyroidism and elevated serum T3 (216 ng/dl), T4 (18.19 micrograms/dl) levels one week after iodinated contrast medium injection, during a neck CT scan examination. The patient eventually received thyroid operation for her goiter and hyperthyroidism. Caution should be done in the administration of iodine-containing drugs, especially iodinated contrast medium in patients with pre-existing thyroid disease.