Last update Jan. 26, 2021

Iodine-131

Limited compatibility

Unsafe. Moderate/severe adverse effects. Compatible under certain circumstances. Follow-up recommended. Use safer alternative or discontinue breastfeeding from 5 to 7 T ½ . Read Commentary.

It has physical half-life of 192 hours (8 days). However, the effective half-life is a function of the biological half-life of every I-131 compound.

I-131Na (sodium compound) is used as treatment or for thyroid testing. It has an effective half-life of 11 hours. It accumulates in thyroid tissue and breast milk. If the dose is higher than 1 mCi breastfeeding should be interrupted (ARSAC 2019).
Even more, it would be desirable delaying the procedure for 4 weeks (Mitchell 2019, Sachs 2013) to 6 weeks (ARSAC 2020, SNMMI2018 & 2011, Am.Thy.Asoc. 2011) after nursing has stopped since the lactating breast concentrates a substantial amount of iodide and the mammal gland may result affected.

If the dose used was lower than 1 mCi (37 MBq) breastfeeding may be resumed after 41 days of interruption and it is neither practical nor easy.


I-131 OIH (sodium ortho-iodide hyppurate) is used for testing. It has an effective half-life of 6 hours. By a nursing interruption of 30 hours there is no risk of irradiation in the infant.

For lactating mothers it is recommended I-123 as a compound for thyroid testing. It would be better the use of a Tecnetium containing compound which is a substance with shorter half-life.

Whenever the continuation of breastfeeding is desired, it is advisable to start pumping and milk may be used to feed the infant while nursing is being interrupted whether alone or together with formula. Once the test is over, mother’s milk may be pumped and discarded, since it is not practical to store in a separated freezer until it achieves 10 physical half-lives (80 days!) at which point the radiation has disappeared and milk become safe.

Radiation level in breast milk can be tested.

The shortest half-life radio-nuclide must be chosen whenever possible.

Alternatives

  • Iodine 123 (Unsafe. Moderate/severe adverse effects. Compatible under certain circumstances. Follow-up recommended. Use safer alternative or discontinue breastfeeding from 5 to 7 T ½ . Read Commentary.)
  • Technetium 99m Sestamibi (MIBI) (Fairly safe. Mild or unlikely adverse effects. Compatible under certain circumstances. Follow-up recommended. Read Commentary.)

Suggestions made at e-lactancia are done by APILAM team of health professionals, and are based on updated scientific publications. It is not intended to replace the relationship you have with your doctor but to compound it. The pharmaceutical industry contraindicates breastfeeding, mistakenly and without scientific reasons, in most of the drug data sheets.

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Other names

Iodine-131 is also known as


Group

Iodine-131 belongs to this group or family:

Tradenames

Main tradenames from several countries containing Iodine-131 in its composition:

Pharmacokinetics

Variable Value Unit
T½ 192 hours
M/P ratio 25 -

References

  1. ARSAC. Administration of Radioactive Substances Advisory Committee. Notes for Guidance on the Clinical Administration of Radiopharmaceuticals and Use of Sealed Radioactive Sources. Section 7 Conception, Pregnancy and Breastfeeding, p. 53-58. ARSAC Support Unit. Centre for Radiation, Chemical and Environmental Hazards. Public Health England. 2020 Consulted on Dec. 4, 2023 Abstract Full text (link to original source) Full text (in our servers)
  2. Mattsson S, Leide-Svegborn S, Andersson M. X-RAY AND MOLECULAR IMAGING DURING PREGNANCY AND BREASTFEEDING-WHEN SHOULD WE BE WORRIED? Radiat Prot Dosimetry. 2021 Oct 12;195(3-4):339-348. Abstract Full text (link to original source)
  3. Mitchell KB, Fleming MM, Anderson PO, Giesbrandt JG; Academy of Breastfeeding Medicine.. ABM Clinical Protocol #30: Radiology and Nuclear Medicine Studies in Lactating Women. Breastfeed Med. 2019 Jun;14(5):290-294. Abstract
  4. IAEA - International Atomic Energy Agency. Radiation Protection and Safety in Medical Uses of Ionizing Radiation IAEA Safety Standards Series No. SSG-46, 2018 Abstract Full text (link to original source)
  5. SNMMI - Society of Nuclear Medicine and Molecular Imaging. Instrucciones para los pacientes que van a recibir tratamiento con Yodo radioactivo (I-131). Hoja informativa. 2018 Full text (link to original source) Full text (in our servers)
  6. Alexander EK, Pearce EN, Brent GA, Brown RS, Chen H, Dosiou C, Grobman WA, Laurberg P, Lazarus JH, Mandel SJ, Peeters RP, Sullivan S. 2017 Guidelines of the American Thyroid Association for the Diagnosis and Management of Thyroid Disease During Pregnancy and the Postpartum. Thyroid. 2017 Abstract Full text (link to original source) Full text (in our servers)
  7. US.NRC - Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards. Apéndice U, Tabla U.3. Consolidated guidance about materials licenses. Program-specific guidance about medical use licenses. Draft Report for Comment. Appendix U, Table U.3. NUREG-1556. Vol.9, Rev 3. 2016 Full text (link to original source) Full text (in our servers)
  8. Leide-Svegborn S, Ahlgren L, Johansson L, Mattsson S. Excretion of radionuclides in human breast milk after nuclear medicine examinations. Biokinetic and dosimetric data and recommendations on breastfeeding interruption. Eur J Nucl Med Mol Imaging. 2016 Abstract
  9. Prunty JJ, Heise CD, Chaffin DG. Graves' Disease Pharmacotherapy in Women of Reproductive Age. Pharmacotherapy. 2016 Abstract
  10. Sachs HC; Committee On Drugs. The transfer of drugs and therapeutics into human breast milk: an update on selected topics. Pediatrics. 2013 Sep;132(3):e796-809. Abstract Full text (link to original source) Full text (in our servers)
  11. SNMMI - Society of Nuclear Medicine and Molecular Imaging. Guidelines for Patients Receiving Radioiodine I-131 Treatment. Fact Sheet. 2011 Full text (link to original source) Full text (in our servers)
  12. American Thyroid Association Taskforce On Radioiodine Safety., Sisson JC, Freitas J, McDougall IR, Dauer LT, Hurley JR, Brierley JD, Edinboro CH, Rosenthal D, Thomas MJ, Wexler JA, Asamoah E, Avram AM, Milas M, Greenlee C. Radiation safety in the treatment of patients with thyroid diseases by radioiodine 131I : practice recommendations of the American Thyroid Association. Thyroid. 2011 Abstract Full text (link to original source) Full text (in our servers)
  13. Stagnaro-Green A, Abalovich M, Alexander E, Azizi F, Mestman J, Negro R, Nixon A, Pearce EN, Soldin OP, Sullivan S, Wiersinga W; American Thyroid Association Taskforce on Thyroid Disease During Pregnancy and Postpartum.. Guidelines of the American Thyroid Association for the diagnosis and management of thyroid disease during pregnancy and postpartum. Thyroid. 2011 Abstract Full text (link to original source) Full text (in our servers)
  14. US.NRC - Howe DB, Beardsley M, Bakhsh S. U.S. Nuclear Regulatory Commission Office of Nuclear Material Safety and Safeguards. Apéndice U, Tabla U.3. Consolidated guidance about materials licenses. Program-specific guidance about medical use licenses. Final report. Appendix U, Table U.3. NUREG-556. Vol.9, Rev 2. 2008 Full text (link to original source) Full text (in our servers)
  15. ICRP. Radiation dose to patients from radiopharmaceuticals. Addendum 3 to ICRP Publication 53. ICRP Publication 106. Annex D. Recommendations on breast-feeding interruptions, p. 163-165. Ann ICRP. 2008 Abstract Full text (link to original source) Full text (in our servers)
  16. Abalovich M, Amino N, Barbour LA, Cobin RH, De Groot LJ, Glinoer D, Mandel SJ, Stagnaro-Green A. Management of thyroid dysfunction during pregnancy and postpartum: an Endocrine Society Clinical Practice Guideline. J Clin Endocrinol Metab. 2007 Abstract Full text (link to original source) Full text (in our servers)
  17. Azizi F. Treatment of post-partum thyrotoxicosis. J Endocrinol Invest. 2006 Abstract
  18. AEMPS. Yodo131 (Curicap). Ficha técnica. 2005 Full text (in our servers)
  19. Stabin MG, Breitz HB. Breast milk excretion of radiopharmaceuticals: mechanisms, findings, and radiation dosimetry. J Nucl Med. 2000 Abstract Full text (link to original source) Full text (in our servers)
  20. Saenz RB. Iodine-131 elimination from breast milk: a case report. J Hum Lact. 2000 Abstract
  21. Rubow S, Klopper J, Wasserman H, Baard B, van Niekerk M. The excretion of radiopharmaceuticals in human breast milk: additional data and dosimetry. Eur J Nucl Med. 1994 Abstract
  22. Dydek GJ, Blue PW. Human breast milk excretion of iodine-131 following diagnostic and therapeutic administration to a lactating patient with Graves' disease. J Nucl Med. 1988 Abstract Full text (link to original source) Full text (in our servers)
  23. Ahlgren L. Excretion of radionuclides in human breast milk after administration of radiopharmaceuticals. Error in table. J Nucl Med. 1986 Abstract Full text (link to original source) Full text (in our servers)
  24. Ahlgren L, Ivarsson S, Johansson L, Mattsson S, Nosslin B. Excretion of radionuclides in human breast milk after the administration of radiopharmaceuticals. J Nucl Med. 1985 Abstract Full text (link to original source) Full text (in our servers)
  25. Wyburn JR. Human breast milk excretion of radionuclides following administration of radiopharmaceuticals. J Nucl Med. 1973 Abstract Full text (link to original source) Full text (in our servers)
  26. Karjalainen P, Penttilä IM, Pystynen P. The amount and form of radioactivity in human milk after lung scanning, renography and placental localization by 131 I labelled tracers. Acta Obstet Gynecol Scand. 1971 Abstract

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