Thyroid dysfunction following a kelp-containing marketed diet

BMJ Case Rep. 2014 Oct 29:2014:bcr2014206330. doi: 10.1136/bcr-2014-206330.


Complementary medications and herbal medicine for weight loss have become very popular. We report a case of thyroid dysfunction following the ingestion of a kelp-containing marketed diet in a 45-year-old woman with no previous thyroid disease. Signs of hyperthyroidism occurred shortly after a kelp-containing diet. Hyperthyroidism lasted 2 months and was followed by an overt hypothyroidism. The thyroid scintiscan exhibited an extremely low uptake and colour-Doppler ultrasonography revealed multiple small areas of pulsatile flow. After 3 months of levothyroxine substitutive therapy, normal thyroid function was recovered after levothyroxine discontinuation. This clinical history is compatible with a case of iodine-induced thyrotoxicosis followed by prolonged block of the sodium-iodide symporter activity as a consequence of excessive iodine consumption from kelp. Consumers of marketed diets containing kelp or other iodine-rich ingredients should be advised of the risk to develop a thyroid dysfunction also in the absence of underlying thyroid disease.

Publication types

  • Case Reports
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Diet, Reducing / adverse effects*
  • Female
  • Humans
  • Hyperthyroidism / chemically induced*
  • Hypothyroidism / chemically induced*
  • Hypothyroidism / drug therapy
  • Iodine / adverse effects*
  • Kelp*
  • Middle Aged
  • Thyroid Gland / diagnostic imaging
  • Thyrotoxicosis / chemically induced
  • Thyroxine / therapeutic use
  • Ultrasonography


  • Iodine
  • Thyroxine