The Basics
What is Sodium Iodide I 123?
Used in a diagnostic procedure to be used in evaluating thyroid function and/or morphology.
Brand names for Sodium Iodide I 123
Sodium Iodide I 123
How Sodium Iodide I 123 is classified
Radiopharmaceuticals, Iodine Radioisotopes, Diagnostic Agents
Sodium Iodide I 123 During Pregnancy
Sodium Iodide I 123 pregnancy category
Category XNote that the FDA has deprecated the use of pregnancy categories, so for some medications, this information isn’t available. We still think it’s useful to list historical info, however, given what a common proxy this has been in the past.
What we know about taking Sodium Iodide I 123 while pregnant
N/A
Taking Sodium Iodide I 123 While Breastfeeding
What are recommendations for lactation if you're taking Sodium Iodide I 123?
Information in this record refers to the use of sodium iodide I 123 as a diagnostic agent. Considerable controversy exists in the literature concerning the breastfeeding interruption time after the diagnostic use of sodium iodide I 123, partly depending on assumptions used for the levels of impurities, especially I 125, in commercial products. Some international agencies state that breastfeeding should be interrupted for more than 3 weeks following diagnostic use of sodium iodide I 123.[1][2] This usually will result in permanent discontinuation of breastfeeding for this infant. However, other experts recommend much shorter times. Recent information indicates that I 125 contamination is currently much less than earlier estimates.[3] The American Thyroid Association recommends discontinuation of breastfeeding for only 3 to 4 days after a diagnostic scan[4] and UK authorities recommend a cessation of 42 hours after a 20 MBq dose.[5] 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.[6] Mothers who receive a dose less than 400 MBq for a thyroid scan need not refrain from close contact with their infants.[7]
Maternal / infant drug levels
Information in this record refers to the use of sodium iodide I 123 as a diagnostic agent. Considerable controversy exists in the literature concerning the breastfeeding interruption time after the diagnostic use of sodium iodide I 123, partly depending on assumptions used for the levels of impurities, especially I 125, in commercial products. Some international agencies state that breastfeeding should be interrupted for more than 3 weeks following diagnostic use of sodium iodide I 123.[1][2] This usually will result in permanent discontinuation of breastfeeding for this infant. However, other experts recommend much shorter times. Recent information indicates that I 125 contamination is currently much less than earlier estimates.[3] The American Thyroid Association recommends discontinuation of breastfeeding for only 3 to 4 days after a diagnostic scan[4] and UK authorities recommend a cessation of 42 hours after a 20 MBq dose.[5] 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.[6] Mothers who receive a dose less than 400 MBq for a thyroid scan need not refrain from close contact with their infants.[7]
Possible effects of Sodium Iodide I 123 on milk supply
Relevant published information was not found as of the revision date.
Possible alternatives to Sodium Iodide I 123
(Hyperthyroidism Diagnosis) Sodium Pertechnetate Tc 99m.
List of References
Lactation sources: Drugs and Lactation Database (LactMed) [Internet]. Bethesda (MD): National Library of Medicine (US); 2006-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK501922/1. 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. Annex D. Recommendations on breast-feeding interruptions. Ann ICRP. 2015;44 (2 Suppl):319-21. PMID: 26069086
2. 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
3. Lofton B, Gibbs G, Stickel J et al. Measured I-125 contamination in I-123. Med Phys. 2017;44:3127. Abstract. DOI: doi:10.1002/mp.12304
4. Alexander EK, Pearce EN, Brent GA et al. 2016 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease during Pregnancy and the Postpartum. Thyroid. 2017;27:315-89. PMID: 28056690
5. National Radiation Protection Board (UK). Administration of radioactive substances advisory committee. Notes for guidance on the clinical administration of radiopharmaceuticals and use of sealed radioactive sources. 2019. https://assets.publishing.service.gov.uk/government/…/file/…/ARSAC_NfG_2019.pdf
6. Stabin MG, Breitz HB. Breast milk excretion of radiopharmaceuticals: mechanisms, findings, and radiation dosimetry. J Nucl Med. 2000;41:863-73. PMID: 10809203
7. Mountford PJ, O’Doherty MJ. Exposure of critical groups to nuclear medicine patients. Appl Radiat Isot. 1999;50:89-111. PMID: 10028630
8. Howe DB, Beardsley M, Bakhsh S. Appendix U. Model procedure for release of patients or human research subjects administered radioactive materials. In, NUREG-1556. Consolidated guidance about materials licenses. Program-specific guidance about medical use licenses. Final report. U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards. 2008;9, Rev. 2. http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1556/v9/r2/
9. Mountford PJ, Coakley AJ. A review of the secretion of radioactivity in human breast milk: data, quantitative analysis and recommendations. Nucl Med Commun. 1989;10:15-27. PMID: 2645546
Disclaimer: This material is provided for educational purposes only and is not intended for medical advice, diagnosis, or treatment. Consult your healthcare provider with any questions.
