Iodine-131 in breast milk following therapy for thyroid carcinoma

This study evaluates breast milk secretion of 131I following therapeutic administration of 4000 MBq of 131I-iodide during lactation.

Breast milk 131I activity concentration was measured over a 32-day period. Dosimetry calculations were undertaken to estimate the period for discontinuation of breast feeding and the equivalent dose to the breasts.

To achieve an infant effective dose < 1 mSv and an infant thyroid dose < 10 mSv, breast feeding would need to be discontinued for at least 52 days. The estimated equivalent dose to the breasts was 1.6 Gy.

It is suggested that 131I-iodide administration is not undertaken during lactation and that breast feeding is discontinued several days prior to administration.