Hyperthyroidism and Antithyroid Drugs

Antithyroid drugs for long-term therapy (C). Thiourea derivatives 

Perchlorate, given orally as the sodium salt, inhibits the iodide pump. Adverse reactions include aplastic anemia. Compared with thioamides, its therapeutic importance is low but it is used as an adjunct in scintigraphic imaging of bone by means of technetate when accumulation in the thyroid gland has to be blocked. 

Short-term thyroid suppression (C). Iodine in high dosage ( 6000 pg/d) exerts a transient thyrostatic effect in hyperthyroid, but usually not in euthyroid, individuals. Since release is also blocked, the effect develops more rapidly than does that of thioamides. 

Clinical applications include preoperative suppression of thyroid secretion according to Plummer with Lugol s solution (5% iodine + 10% potassium iodide, 50-100 mg iodine/d for a maximum of 10 d). In thyrotoxic crisis, LugoTs solution is given together with thioamides and p-blockers. Adverse effects allergies contraindications iodine-induced thyrotoxicosis. 

Lithium ions inhibit thyroxine release. Lithium salts can be used instead of iodine for rapid thyroid suppression in iodine-induced thyrotoxicosis. Regarding administration of lithium in manic-depressive illness, see p. 234. 

---