Iodohippurate Sodium I 123 and Breastfeeding

Summary of use during lactation

Information in this record refers to the use of iodohippurate sodium I 123 (I 123 ortho-iodohippurate; I 123 OIH) as a kidney function diagnostic agent. Some older recommendations are to nurse the infant just before administration of the radiopharmaceutical and interrupt breastfeeding for 8 to 12 hours after the dose.[1-3] This recommendation is based on possible contamination with other iodine isotopes, which no longer occurs, so a US Nuclear Regulatory Commission subcommittee has recommended that breastfeeding should be interrupted for only 4 hours after administration of I 123 OIH in doses up to 100 MBq (2.7 mCi) to a nursing mother.[4] Others recommend that no interruption is necessary with doses of 74 MBq (2 mCi).[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.[1,6] Mothers need not refrain from close contact with their infants after usual clinical doses.[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]

Drug levels in milk and infant serum

I 123 is a gamma emitter with a photon energy of 159 keV and a physical half-life of 13.1 hours.[4] The effective half-life of I 123 OIH ranges from 3.5 to 5.8 hours.[1,8]

Effects in breastfed infants

Relevant published information was not found as of the revision date.

Effects on lactation and breastmilk

Relevant published information was not found as of the revision date.

References

1. Mountford P, Coakley A. A review of the secretion of radioactivity in human breast milk: Data, quantitative analysis and recommendations. Nucl Med Commun 1989;10:15-27.2645546 PubMed
2. Mattsson S, Johansson L, Leide Svegborn S, et al. Radiation dose to patients from radiopharmaceuticals: A compendium of current information related to frequently used substances. ICRP Publication 128. Annex D. Recommendations on breast-feeding interruptions. Ann ICRP 2015;44:7-321. doi:10.1177/014664531455801926069086 PubMed
3. International Atomic Energy Agency. Radiation Protection and Safety in Medical Uses of Ionizing Radiation, IAEA Safety Standards Series No. SSG-46, IAEA, Vienna. 2018. https://www.iaea.org/publications/11102/radiation-protection-and-safety-in-medical-uses-of-ionizing-radiation
4. Dilsizian V, Metter D, Palestro C, et al. Advisory Committee on Medical Uses of Isotopes (ACMUI) Sub-Committee on Nursing Mother Guidelines for the Medical Administration of Radioactive Material. Final report submitted: January 31, 2019. 2019. https://www.nrc.gov/docs/ML1903/ML19038A498.pdf
5. Stabin M. Doses from medical radiation sources. https://hps.org/hpspublications/articles/dosesfrommedicalradiation.html. Accessed Nov 6, 2024.
6. ARSAC notes for guidance: Good clinical practice in nuclear medicine. Notes for guidance on the clinical administration of radiopharmaceuticals and use of sealed radioactive sources. 2020. https://www.gov.uk/government/publications/arsac-notes-for-guidance
7. Mountford P, O'Doherty M. Exposure of critical groups to nuclear medicine patients. Appl Radiat Isot 1999;50:89-111.10028630 PubMed
8. Stabin M, Breitz H. Breast milk excretion of radiopharmaceuticals: Mechanisms, findings, and radiation dosimetry. J Nucl Med 2000;41:863-73.10809203 PubMed