Is Sodium Iodide I 123 safe while breastfeeding?
Here is what LactMed, the Drugs and Lactation Database published by the U.S. National Institute of Child Health and Human Development (NICHD), reports about Sodium Iodide I 123. The text below is quoted from that source — it is not our own verdict.
Summary of use during breastfeeding
Information in this record refers to the use of sodium iodide I 123 as a diagnostic agent. A US Nuclear Regulatory Commission subcommittee and the American Thyroid Association recommend discontinuation of breastfeeding for 3 to 4 days after a diagnostic scan.[1,2] and UK authorities recommend a cessation of 42 hours after a 20 MBq dose.[3] These values assume no contamination with I 124 or I 125, which has been reported in the past.[4] The safest course of action may be to have breastmilk tested at a nuclear medicine facility at a hospital. When the radioactivity is at a safe level the mother may resume breastfeeding. A method for measuring milk radioactivity and determining the time when a mother can safely resume breastfeeding has been published.[5] Mothers who receive a dose less than 400 MBq for a thyroid scan need not refrain from close contact with their infants.[6]
Effects on the breastfed infant
Relevant published information was not found as of the revision date.
Effects on milk supply
Relevant published information was not found as of the revision date.
Levels in milk
I 123 is a gamma emitter with a principal photon energy of 159 keV and a physical half-life of 13.1 hours.[1] Iodide is actively secreted into breastmilk by the NaI symporter, which is stimulated by lactation, and actively taken up by the mother's and infant's thyroid glands.[7] The maximum effective half-life of I 123 is 10.4 hours.[3]
Maternal Levels. Relevant published information was not found as of the revision date.
Infant Levels. Relevant published information was not found as of the revision date.
“No published information” means the studies do not exist yet — not that Sodium Iodide I 123 is known to be harmful, and not that it is known to be safe. Your prescriber or pharmacist can weigh your baby's age and whether a better-studied alternative would do the same job. Worth asking before stopping a medicine you need.
Source: Drugs and Lactation Database (LactMed), National Institute of Child Health and Human Development (NICHD), via NCBI Bookshelf, record “Sodium Iodide I 123” (LM666). LactMed on NCBI Bookshelf. LactMed is a registered trademark of the U.S. Department of Health and Human Services.
Educational summary of an authoritative source — not medical advice. Never start, stop, or change a medicine while breastfeeding without confirming with your doctor.