Is Iodohippurate Sodium I 131 safe while breastfeeding?

Summary of use during breastfeeding

Information in this record refers to the use of iodohippurate sodium I 131 (ortho-iodohippurate sodium I 131; I-131 OIH) as a diagnostic agent. A US Nuclear Regulatory Commission subcommittee has recommended that breastfeeding should be interrupted for 4 hours after administration of I-131 OIH, while others recommend no discontinuation with doses of 11.1 MBq (0.3 mCi) or less.[1,2] However, some experts recommend nursing the infant just before administration of the radiopharmaceutical and interrupting breastfeeding for 12 to 30 hours after the dose.[3-5] If the mother has expressed and saved milk prior to the examination, she can feed it to the infant during the period of nursing interruption.[3,6,7] Mothers concerned about the level of radioactivity in their milk could ask to have it tested at a nuclear medicine facility at their hospital. When the radioactivity is at a safe level, she may resume breastfeeding. A method for measuring milk radioactivity and determining the time when a mother can safely resume breastfeeding has been published.[8]

Nursing mothers should not work with substances containing I 131 in their workplace.[9]

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 131 is a beta and high-energy gamma emitter with a main gamma emission energy of 364 keV and a physical half-life of 8.04 days.[1] The effective half-life of I-131 OIH averages 4.5 to 6.3 hours (range 2.2 to 7.6 hours).[3,4,8] About 2.4% of an administered dose is excreted into breastmilk.[4]