Technetium Tc 99m White Blood Cells and Breastfeeding

Summary of use during lactation

Information in this record refers to the use of technetium Tc 99m white blood cells as a diagnostic agent. After a dose of 185 MBq (5 mCi), breastfeeding should be withheld for 48 hours.[1] The mother can nurse just before administration of the radiopharmaceutical. During the period of interruption, the breasts should be emptied regularly and completely. 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.[2-4] The milk that is pumped by the mother during the time of breastfeeding interruption can either be discarded or stored refrigerated and given to the infant after 10 physical half-lives, or about 60 hours, have elapsed. Mothers need not refrain from close contact with their infants after usual clinical doses.[5] 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.[6] For nursing mothers who work with Tc 99m substances in their workplace, there is no need to take any precautions other than those appropriate for general radiation protection.[7]

Drug levels in milk and infant serum

Tc 99m is a gamma emitter with a principal photon energy of 140 keV and a physical half-life of 6.04 hours.[8] The effective half-life of technetium Tc 99m white blood cells ranges from 3.2 to 3.8 hours.[6]

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. Stabin MG. Doses from medical radiation sources. https://hps.org/hpspublications/articles/dosesfrommedicalradiation.html. Accessed Nov 6, 2024.
2. Mountford PJ, Coakley AJ. A review of the secretion of radioactivity in human breast milk: Data, quantitative analysis and recommendations. Nucl Med Commun 1989;10:15-27.2645546 PubMed
3. Early PJ, Sodee DB. Principles and practice of nuclear medicine. 2nd ed. St. Louis: Mosby-Year Book, Inc; 1995:1380-1.
4. 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
5. Mountford PJ, O'Doherty MJ. Exposure of critical groups to nuclear medicine patients. Appl Radiat Isot 1999;50:89-111.10028630 PubMed
6. Stabin MG, Breitz HB. Breast milk excretion of radiopharmaceuticals: Mechanisms, findings, and radiation dosimetry. J Nucl Med 2000;41:863-73.10809203 PubMed
7. Almén A, Mattsson S. Radiological protection of foetuses and breast-fed children of occupationally exposed women in nuclear medicine - Challenges for hospitals. Phys Med 2017;43:172-7.28882410 PubMed
8. 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