eMedicine Specialties > Endocrinology > Thyroid

Iodine Deficiency: Treatment & Medication

Author: Stephanie L Lee, MD, PhD, Fellow, Association of Clinical Endocrinology; Director of Thyroid Nodule and Cancer Center, Associate Chief, Section of Endocrinology, Diabetes and Nutrition, Boston Medical Center; Associate Professor, Department of Medicine, Boston University School of Medicine
Coauthor(s): Sonia Ananthakrishnan, MD, Attending Physician, Department of Medicine, Section of Endocrinology, Diabetes and Nutrition, Boston University School of Medicine/Boston Medical Center; Elizabeth N Pearce, MD, MSc, Assistant Professor of Medicine, Boston Medical Center/Boston University Medical School
Contributor Information and Disclosures

Updated: Apr 22, 2009

Treatment

Medical Care

Long-term dietary iodine replacement at levels recommended by the 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.⁴ Generally, long-standing goiters associated with iodine deficiency disorder 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 by 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 the eMedicine topics Thyroiditis, Subacute and Hyperthyroidism for more information.)
  • Radioactive iodine (iodine-131 [¹³¹ I]) has been used, primarily in Europe, to decrease thyroid volume in patients with euthyroid goiters (40-60% volume reduction). In the United States,¹³¹ I 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.

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.^3,4,5,6

• 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.⁷  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.⁸
• 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.^8,9,7

Activity

No restrictions are needed.

Medication

Correction of an individual's iodine deficiency should be instituted at a level recommended by the Food and Drug Administration (FDA) and the WHO. In an adult, 150 mcg/d is sufficient for normal thyroid function. Using highly concentrated pharmaceutical agents, such as SSKI (35,000-50,000 mcg/gtt), is impractical and potentially dangerous. Replacement of iodine is achieved most easily by requesting that the patient use iodized salt (70 mcg/g) 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 by injecting people with iodized oil.

Adult multiple vitamins do not all contain iodine. Those that do, typically contain iodine have 150 mcg per tablet.

¹³¹ I has been used in Europe to decrease the size of nontoxic goiters caused by iodine deficiency. This is not the standard of care in the United States. Risks associated with¹³¹ I therapy include permanent hypothyroidism.

Iodides

Iodine deficiency has been treated at a population level by several methods, including voluntary use of iodized salt, iodine supplementation in bread and water, and PO/IM administration of iodized oil. The simplest and least expensive treatment is to have the patient purchase and use iodized salt.

Potassium iodide (Lugol solution, SSKI, Pima)

Option in industrialized counties. Absorption from GI tract is rapid and complete. Skin and lungs also can absorb iodine. Iodine equilibrates in extracellular fluids and is specifically concentrated by thyroid gland.

Thyroid hormones

Thyroid hormone, L-thyroxine, may be used to treat iodine deficiency, because the chemical content of iodine is approximately 60% by weight.

Levothyroxine (Synthroid, Levothroid, Levoxyl)

Generally effective in replacing iodine deficiency. Considerably more expensive preparation than other forms of iodine (eg, iodized salt), especially when combined with the added expense of measuring TSH levels to assure that the supplemental L-thyroxine has not resulted in iatrogenic hyperthyroidism. Alternatively, thyroid hormone therapy has been used with caution to shrink the goiter of iodine deficiency. An L-thyroxine dose is chosen that maintains the TSH in the lower part of the reference range. TSH levels should be monitored carefully to avoid thyrotoxicosis due to autonomous nodules in the iodine deficiency goiter.

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