Iodide therapy

Large doses of iodide inhibit the synthesis and release of thyroid hormones. Serum T4 levels may be reduced within 24 hours, and the effects may last for 2 to 3 weeks. Iodides are used most commonly in Graves disease patients prior to surgery and to quickly reduce hormone release in patients with thyroid storm. Potassium iodide is administered either as a saturated solution (SSKI) that contains 38 mg iodide per drop or as Lugol s solution, which contains 6.3 mg iodide per drop. The typical starting dose is 120 to 400 mg/day. Iodide therapy should start 7 to 14 days prior to surgery. Iodide should not be... 

Disadvantages of iodide therapy include an increase in intraglandular stores of iodine, which may delay onset of thioamide... 

Friend DG. Iodide therapy and the importance of quantitating the dose. N Engl J Med 1960 263 1358-60. 

Dolan TF Jr. and Gibson LE (1971) Complications of iodide therapy in patients with cystic fibrosis. Pediatrics 79 684-687. 

Iodide therapy (usually saturated solution of potassium iodide) is useful in reducing thyroid hormone release and in decreasing the vascularity of the gland prior to surgery. However, escape from the inhibitory effect of iodide often occurs in Graves disease, and the increased iodine substrate made available by the therapy may actually accentuate the disease. 

Axcisson. U. (1969). Glaucoma, miotic therapy and cataract. V. Studies on the lens in glaucoma eyes after discontinuance of ccothiophate pho.spholinc iodide therapy. Acta Ophthalmol. 47, 1049-1046. 

TABLE 3. Iodine concentration of goiters in children and adolescents before and during iodide therapy (100-150 ng daily) for 4-8 months and before and during L-thyroxine therapy (6 month)... 

The administration of SSKI a few days after for the treatment of hyperthyroid Graves disease and continued for weeks later has been reported to more rapidly ameliorate the symptoms of thyrotoxicosis and to reduce the dose of l necessary to effectively treat the hyperthyroidism (10). However, hypothyroidism not infrequently occurred during iodide therapy and disappeared when iodides were discontinued. Years ago, we reported that the administration of 5 drops SSKI to euthyroid patients treated years earlier with 1 or surgery for Graves disease almost always induced hypothyroidism within weeks (11). The euthyroid state rapidly returned when the iodine was withdrawn. It is likely that these... 

Committee on Drugs (1976) Adverse reactions to iodide therapy of asthma and other pulmonary diseases. Pediatrics, 57, 272. 

A variety of therapies for thallium poisoning have been suggested by neutralising thallium in the intestinal tract, hastening excretion after resorption, or decreasing absorption. Berlin-Blue (fertihexacyanate) and sodium iodide in a 1 wt % solution have been recommended. Forced diuresis hemoperfusion and hemodialysis in combination results in the elimination of up to 40% of the resorbed thaHous sulfate (39). 

There is an additive bone marrow depression when methimazole or propylthiouracil is administered with otiier bone marrow depressants, such as the antineo-plastic drugs, or witii radiation therapy. When methimazole is administered with digitalis, there is an increased effectiveness of the digitalis and increased risk of toxicity. There is an additive effect of propylthiouracil when the drug is administered with lithium, potassium iodide, or sodium iodide When iodine products are administered with litiiium products, synergistic hypotiiyroid activity is likely to occur. 

Radioactive iodine is given by tlie primary health care provider, orally as a single dose The effects of iodides are evident within 24 hours, with maximum effects attained after 10 to 15 days of continuous therapy. If the patient is hospitalized, radiation safety precautions identified by the hospital s department of nuclear medicine are followed. 

Subtotal thyroidectomy is indicated in patients with very large goiters and thyroid malignancies and those who do not respond or cannot tolerate other therapies. Patients must be euthyroid prior to surgery, and patients often are administered iodide preoperatively to reduce gland vascularity. The overall surgical complication rate is 2.7%. Postoperative hypothyroidism occurs in 10% of patients who undergo subtotal thyroidectomy. 

Iodides are often used as adjunctive therapy to prepare a patient with Graves disease for surgery, to acutely inhibit thyroid hormone release and quickly attain the euthyroid state in severely thyrotoxic patients with cardiac decompensation, or to inhibit thyroid hormone release after RAI therapy. 

Blockers are usually used as adjunctive therapy with antithyroid drugs, RAI, or iodides when treating Graves disease or toxic nodules in preparation for surgery or in thyroid storm. /3-Blockers are primary therapy only for thyroiditis and iodine-induced hyperthyroidism. 

Iodides should not be used alone since the normal gland will escape from iodide blockade in 2-8 weeks. Chronic use in pregnancy is not recommended because it crosses placenta and cause fetal goitre. Iodide treatment results in high intrathyroidal iodide content that can delay the onset of thioamide therapy or delay the use for radioactive iodine therapy for weeks if not months. Adverse effects include Hodism which is rare and reversible. The clinical symptoms are acneiform rash, sialadenitis, mucous membrane ulceration, conjuctivitis, rhinor-rhoea, metallic taste and rarely anaphylactoid reaction. 

Prior to the introduction of the thioamides in the 1940s, iodides were the major antithyroid agents today they are rarely used as sole therapy. 

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