eMedicine Specialties > Endocrinology > Thyroid

Iodine Deficiency: Follow-up

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

Follow-up

Further Outpatient Care

  • In population-based assessments, iodine sufficiency can be determined based on the results of a spot urine test for iodine and creatinine.8 Supplementation can be achieved by using iodized salt in cooking or a once-daily multiple vitamin containing sodium iodide, 150 mcg/d.3

Deterrence/Prevention

  • At a population level, iodine deficiency disorder can be prevented by the iodination of food products or the water supply. In practice, this is usually achieved by iodination of salt. An alternative in some developing countries has been the periodic injection of iodized oil supplements.

Complications

The primary complication of iodine therapy for iodine deficiency disorder is the development of hyperthyroidism. This may occur, especially in patients older than 45 years, because of the hyperfunctioning areas of autonomy that tend to develop in patients with long-standing iodine-deficient goiters.12

A Danish study investigating the incidence of hyperthyroidism associated with Denmark's iodine fortification program found that, based on the incident use of antithyroid medication in various parts of the country, the incidence of hyperthyroidism was greater among persons who had suffered from moderate iodine deficiency than it was among those who had had only a mild deficiency.13 In the moderately deficient population, the incident use of antithyroid medication increased the most in persons below age 40 years or above age 75 years. Four years after iodine fortification began, the incidence of hyperthyroidism apparently began to decline, returning to prefortification rates in most population groups by the end of 6 years.

Prognosis

  • The supplementation of iodine does not reverse cretinism or reduce the size of large nodular goiters. Small diffuse goiters of short duration that occur in infants or during pregnancy appear to be managed effectively with iodine supplementation.
  • Iodine deficiency can recur if iodine supplementation programs lapse. Recurrence of goiter and new cases of cretinism have been noted in some nations where this has occurred. These changes are manifested prominently in school-aged children, who are particularly sensitive to variations in iodine intake. Thyroid volume, prevalence of goiter, and urinary iodine levels may return to pre-iodine supplementation levels 1-2 years following the discontinuation of iodine supplementation.

Patient Education

  • Importantly, the public must understand the importance of using iodized salt, especially in the United States, where iodization of salt is not mandated by law. Several areas of the world, including the United States, Australia, and the Netherlands, in which iodine deficiency had been eradicated by voluntary methods, have later shown a significant decrease in iodine intake.
  • Surveillance techniques to monitor iodine sufficiency include assessment of thyroid volume, urinary iodine concentration, dried whole-blood spot Tg levels, and dietary questionnaires; the last method is the least reliable.
  • There has been particular interest in monitoring iodine sufficiency in pregnant women and school-aged children. These populations are important, because they are easily accessible and are particularly vulnerable to the adverse effects caused by iodine deficiency.
  • For excellent patient education resources, visit eMedicine's Endocrine System Center and Pregnancy and Reproduction Center. Also, see eMedicine's patient education articles Thyroid Problems and Miscarriage.

Miscellaneous

Medicolegal Pitfalls

  • Failure to consult with an endocrinologist when the etiology of thyroid abnormalities is unclear is a possible medicolegal pitfall.

Special Concerns

  • Iodine stores within the thyroid increase with age in pediatric patients. Therefore, infants and young children tend to have higher131 I uptake than do adults. Additionally, newborns and young infants are much more severely affected by iodine deficiency than are adults and are more likely to become overtly hypothyroid.
  • Women with severe iodine deficiency are more likely to experience infertility, and pregnancy in this group is more likely to result in miscarriage or congenital anomalies. Thyroid hormones are essential for fetal brain growth and development, and severe maternal iodine deficiency may lead to mental retardation or cretinism in offspring. Even in areas of borderline iodine intake, as many as 10% of women may develop goiter during pregnancy.
 


More on Iodine Deficiency

Overview: Iodine Deficiency
Differential Diagnoses & Workup: Iodine Deficiency
Treatment & Medication: Iodine Deficiency
Follow-up: Iodine Deficiency
Multimedia: Iodine Deficiency
References
Further Reading
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References

  1. Zimmermann MB, Jooste PL, Pandav CS. Iodine-deficiency disorders. Lancet. Oct 4 2008;372(9645):1251-62. [Medline].

  2. de Benoist B, McLean E, Andersson M, Rogers L. Iodine deficiency in 2007: global progress since 2003. Food Nutr Bull. Sep 2008;29(3):195-202. [Medline].

  3. Zimmermann MB. Iodine deficiency in pregnancy and the effects of maternal iodine supplementation on the offspring: a review. Am J Clin Nutr. Feb 2009;89(2):668S-72S. [Medline].

  4. WHO Secretariat, Andersson M, de Benoist B, Delange F, Zupan J. Prevention and control of iodine deficiency in pregnant and lactating women and in children less than 2-years-old: conclusions and recommendations of the Technical Consultation. Public Health Nutr. Dec 2007;10(12A):1606-11. [Medline].

  5. Delange F. Optimal iodine nutrition during pregnancy, lactation and neonatal period. Int J Endocrinol Metab. 2004;89:3851.

  6. Azizi F, Smyth P. Breastfeeding and maternal and infant iodine nutrition. Clin Endocrinol (Oxf). May 2009;70(5):803-9. [Medline].

  7. Hollowell JG, Staehling NW, Hannon WH, et al. Iodine nutrition in the United States. Trends and public health implications: iodine excretion data from National Health and Nutrition Examination Surveys I and III (1971-1974 and 1988-1994). J Clin Endocrinol Metab. Oct 1998;83(10):3401-8. [Medline]. [Full Text].

  8. Caldwell KL, Jones R, Hollowell JG. Urinary iodine concentration: United States National Health And Nutrition Examination Survey 2001-2002. Thyroid. Jul 2005;15(7):692-9. [Medline].

  9. Caldwell KL, Miller GA, Wang RY, Jain RB, Jones RL. Iodine status of the U.S. population, National Health and Nutrition Examination Survey 2003-2004. Thyroid. Nov 2008;18(11):1207-14. [Medline].

  10. Williams GR. Neurodevelopmental and neurophysiological actions of thyroid hormone. J Neuroendocrinol. Jun 2008;20(6):784-94. [Medline].

  11. Zimmermann MB, Moretti D, Chaouki N, et al. Development of a dried whole-blood spot thyroglobulin assay and its evaluation as an indicator of thyroid status in goitrous children receiving iodized salt. Am J Clin Nutr. Jun 2003;77(6):1453-8. [Medline]. [Full Text].

  12. Zimmermann MB. Iodine requirements and the risks and benefits of correcting iodine deficiency in populations. J Trace Elem Med Biol. 2008;22(2):81-92. [Medline].

  13. Cerqueira C, Knudsen N, Ovesen L, et al. Association of iodine fortification with incident use of anti-thyroid medication - A Danish nationwide study. J Clin Endocrinol Metab. Apr 14 2009;[Medline].

  14. DeLange FM. Iodine deficiency. In: Braverman L, Utiger RD, eds. Werner and Ingbar's The Thyroid: A Fundamental and Clinical Text. 8th ed. Philadelphia, Pa: Lippincott Williams & Wilkins; 2000:295-316.

  15. Dunn JT. IDD Newsletter. International Council for Control of Iodine Deficiency Disorders. 2001.

  16. Dunn JT, Van der Har F. A practical guide to the correction of iodine deficiency. The Netherlands: International Council for Control of Iodine Deficiency Disorders. 1990.

  17. Hetzel BS. The Story of Iodine Deficiency: An International Challenge in Nutrition. New York, NY: Oxford University Press; 1989.

  18. Hetzel BS, DeLange F. The iodine deficiency disorders. Thyroid Disease Manager [serial online]. 2001. Available from: Worchester, Mass: Endocrine Education. Available at http://www.thyroidmanager.org/Chapter20/20-frame.htm.

  19. Lee K, Bradley R, Dwyer J, Lee SL. Too much versus too little: the implications of current iodine intake in the United States. Nutr Rev. Jun 1999;57(6):177-81. [Medline].

  20. Santiago-Fernandez P, Torres-Barahona R, Muela-Martínez JA, et al. Intelligence quotient and iodine intake: a cross-sectional study in children. J Clin Endocrinol Metab. Aug 2004;89(8):3851-7. [Medline]. [Full Text].

  21. Zimmermann MB, Aeberli I, Torresani T, et al. Increasing the iodine concentration in the Swiss iodized salt program markedly improved iodine status in pregnant women and children: a 5-y prospective national study. Am J Clin Nutr. Aug 2005;82(2):388-92. [Medline]. [Full Text].

  22. Zimmermann MB, Wegmuller R, Zeder C, et al. Rapid relapse of thyroid dysfunction and goiter in school-age children after discontinuation of salt iodization. Am J Clin Nutr. Apr 2004;79(4):642-5. [Medline]. [Full Text].

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Keywords

iodine deficiency, thyroid, iodine, hypothyroidism, thyroid disease, hyperthyroidism, hypothyroid, thyroid symptoms, thyroiditis, hyperthyroid, thyroid hormone, goiter symptoms of thyroid, iodine supplements, symptoms of thyroid problems, thyroid disorder, thyroxine, thyroid disorders, thyroid tests, thyroid hormones, T3 thyroid, T4 thyroid, thyrotoxicosis, iodine foods, iodine diet, iodine supplement, iodine deficiency disorders, endemic goiter, cretinism, mental retardation

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Contributor Information and Disclosures

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
Stephanie L Lee, MD, PhD is a member of the following medical societies: American College of Endocrinology, American Thyroid Association, and Endocrine Society
Disclosure: Nothing to disclose.

Coauthor(s)

Sonia Ananthakrishnan, MD, Attending Physician, Department of Medicine, Section of Endocrinology, Diabetes and Nutrition, Boston University School of Medicine/Boston Medical Center
Disclosure: Nothing to disclose.

Elizabeth N Pearce, MD, MSc, Assistant Professor of Medicine, Boston Medical Center/Boston University Medical School
Elizabeth N Pearce, MD, MSc is a member of the following medical societies: American Association of Clinical Endocrinologists, American Thyroid Association, Endocrine Society, and Massachusetts Medical Society
Disclosure: Abbott Laboratories Consulting fee Consulting

Medical Editor

Harris C Taylor, MD, Clinical Professor of Medicine, Division of Clinical and Molecular Endocrinology, Case Western Reserve University School of Medicine
Harris C Taylor, MD is a member of the following medical societies: American Association of Clinical Endocrinologists, American College of Physicians, American Thyroid Association, and Endocrine Society
Disclosure: Nothing to disclose.

Pharmacy Editor

Francisco Talavera, PharmD, PhD, Senior Pharmacy Editor, eMedicine
Disclosure: Nothing to disclose.

Managing Editor

Arthur B Chausmer, MD, PhD, FACP, FACE, FACN, CNS, Professor of Medicine (Endocrinology, Adj), Johns Hopkins School of Medicine; Affiliate Research Professor, Bioinformatics and Computational Biology Program, School of Computational Sciences, George Mason University; Principal, C/A Informatics, LLC
Arthur B Chausmer, MD, PhD, FACP, FACE, FACN, CNS is a member of the following medical societies: American Association of Clinical Endocrinologists, American College of Endocrinology, American College of Nutrition, American College of Physician Executives, American College of Physicians, American College of Physicians-American Society of Internal Medicine, American Medical Informatics Association, American Society for Bone and Mineral Research, American Society of Law Medicine and Ethics, Endocrine Society, and International Society for Clinical Densitometry
Disclosure: Nothing to disclose.

CME Editor

Mark Cooper, MBBS, PhD, FRACP, Head, Diabetes & Metabolism Division, Baker Heart Research Institute, Professor of Medicine, Monash University
Disclosure: Nothing to disclose.

Chief Editor

George T Griffing, MD, Professor of Medicine, St Louis University School of Medicine
George T Griffing, MD is a member of the following medical societies: American Association for the Advancement of Science, American College of Medical Practice Executives, American College of Physician Executives, American College of Physicians, American Diabetes Association, American Federation for Medical Research, American Heart Association, Central Society for Clinical Research, Endocrine Society, International Society for Clinical Densitometry, and Southern Society for Clinical Investigation
Disclosure: Nothing to disclose.

 
 
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