[Risk of hyperthyroidism in examinations with contrast media]

Investigations with contrast media inevitably lead to the patient being exposed to large amounts of iodine. Under certain preconditions this gentails danger for the patient by causing either iodine-induced hyperthyroidism, which is difficult to treat, or even a thyrotoxic crisis. Patients with normal thyroid function and size have only minute changes of thyroid hormones and TSH within the normal range and are not at risk. Patients with unknown hyperthyroidism--independent of the etiological form--and patients with functional autonomy are at risk of exacerbation of pre-existing hyperthyroidism or development of iodine-induced hyperthyroidism. This development depends on two factors: a) the volume of autonomous tissue and b) the quantity of iodine exposure. Besides contrast media, other sources of iodine excess are possible, such as iodine-containing disinfectants, secretolytic agents, antiarrhythmics like amiodarone, eye drops and ointments, geriatrics, skin ointments, toothpaste etc. The development of hyperthyroidism can be prevented by combined treatment with antithyroid drugs and perchlorate in the case of preexisting hyperthyroidism or the urgent clinical suspicion of thyrotoxicosis or with perchlorate alone, when the patients is euthyroid and does not have a large nodular goitre.