Medical Care
Long-term dietary iodine replacement at levels recommended by the US IOM and WHO may decrease the size of iodine-deficient goiters in very young children and pregnant women and is indicated for all patients with iodine deficiency. Generally, long-standing IDD goiters respond with only small amounts of shrinkage after iodine supplementation, and patients are at risk for developing hyperthyroidism. Patients do not routinely require specific therapy unless the goiter is large enough to cause compressive symptoms (eg, tracheal obstruction, thoracic inlet occlusion, hoarseness).
Correction of an iodine deficiency
This should be instituted based on the recommendations of the IOM and the WHO.
In an adult, 150 mcg/d is sufficient for normal thyroid function. Using highly concentrated pharmaceutical agents such as a saturated solution of potassium iodide (SSKI), ie, 35,000-50,000 mcg/drop, is impractical and potentially dangerous.
Not all daily or prenatal multiple vitamins contain iodine. Adult multiple vitamins that contain iodine typically contain 150 mcg of iodine per tablet.
Replacement of iodine is most easily achieved by requesting that the patient use iodized salt in their cooking and at the table. Other alternative food sources include milk, egg yolks, and saltwater fish.
In developing countries, eradication of iodine deficiency has been accomplished by adding iodine drops to well water or injecting people with iodized oil.
Treatment of nontoxic goiters caused by iodine deficiency
Exogenous L-thyroxine (L-T4) can also be used to decrease goiter size but generally is not effective in adults and older children. Supplemental L-T4, when added to the T3 and T4 secretion by the autonomous nodules in the endemic goiter, may cause thyrotoxicosis. Long-term L-T4 therapy that results in the suppression of the TSH level to below-normal levels may have deleterious effects on cardiac and bone health; therefore, L-T4 therapy is no longer routinely administered to patients with goiter. See Thyroiditis, Subacute and Hyperthyroidism for more information.
Radioactive iodine (I-131) has been used, primarily in Europe, to decrease thyroid volume in patients with euthyroid goiters (40-60% volume reduction). In the United States, I-131 is the most common treatment for toxic multinodular goiters associated with hyperthyroidism.
Surgical Care
Thyroidectomy may be indicated for patients with compressive symptoms of a large goiter (see Goiter, Nontoxic).
Consultations
Consultation with an endocrinologist should be considered when the etiology of thyroid abnormalities is unclear.
Diet
The WHO recommendations for iodine intake are 150 mcg/d for adults and adolescents, 200 mcg/d for pregnant or lactating women, 90-120 mcg/d for children aged 1-11 years, and 50-90 mcg/d for infants younger than 1 year. The IOM recommends 150 mcg/d for adults, 220 mcg/d for pregnant women, and 290 mcg/d for lactating women.
Data collected in the United States for NHANES I for the years 1971-1974 showed that the median urine iodine was 320 mcg/L, reflecting adequate dietary iodine intake. However, by the time of NHANES III (1988-1994), the median urinary iodine had fallen to 145 mcg/L. The NHANES 2001-2002 demonstrates the current stability of iodine intake in the United States at 167.8 mcg/L.
In particular, between previous NHANES surveys, the risk for insufficient dietary iodine intake in reproductive-aged women (15-44 y) increased 3.8-fold. This overall decrease in dietary iodine may be a result of reduced intake of eggs and salt, decreased iodine supplementation of cattle feed, decreased iodate conditioners in bread, decreased use of iodized salt in manufactured foods, poor education about the medical necessity of using iodized salt, and reduction in the number of meals made at home.