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Iodine Supplements in Hashimoto’s Thyroiditis

Last Updated: · Doctors
Authors

Question

Patients with Hashimoto’s thyroiditis are more susceptible to developing a Wolf-Chaikoff reaction to iodine excess than patients without thyroid disease. Yet pregnant women are all being recommended by some to take 250 mcg of iodine during pregnancy and lactation. If you make sure pre-pregancy hypothyroid patients are treated to assure TSH<2,5 and once pregnant increase their dose and are strictly followed assuring fT4 serum levels in the top half of non-`pregnancy normalcy, surely these patients, whose fT4 you are monitoring, do not need iodine supplements, and can even by hurt by them if Wolff-Chaikoff is induced. Lactation could be a different case, since breast fed children will get their iodine through the mother’s milk, and even Hashimoto patients should get supplements. Do you agree? In a mildly deficient Iodine area such as Madrid, would you give supplements to Hashimoto patients on LT4 with good fT4 levels during pregnancy?

Isabelle Runkle de la Vega MD, PhD
Madrid

Response

Hashimoto’s patients under T4 treatment do not need to receive iodine supplements; they should be monitored by measuring free T4 and serum TSH during pregnancy, and adapting the T4 dosage. The same holds true for breastfeeding, unless one wishes to increase the iodine supply of the child.

Daniel Glinoer, MD

Follow Up Questions

Thank you. I am glad that we were doing it right. However, Shouldn’t giving the breast-fed baby an adequate supply of iodine be a reason to give the mother iodine during lactation?

Your thyroxin supplement contains sufficient iodine for your breastfed child apart from all the iodine that you ingest by all the foodstuffs that contain iodine.

How about the fetus’ iodine supply? By only giving levothyroxine to the Hashimoto mother are we hurting the fetus from week 21 on, when his thyroid is taking over? Thank you so very much for your prompt reply.

Your thyroxin supplement contains sufficient iodine for your unborn child apart from all the iodine that you ingest by all the foodstuffs that contain iodine.