Excretion of radioactivity in breast milk following injection of 99Tcm-DTPA.

Measurements were made of the concentration of radioactivity in the breast milk of a patient following a 2 mCi (74 MBq) 99Tcm-DTPA dynamic renal scan. The concentration of activity was 0.88 nCi-1 ml at 2.75 h after injection and it decreased exponentially with an effective halflife of 4.3 h. The potential radiation dose to a breast-fed infant was small enough to conclude that breast feeding need only be interrupted for 4 h after injection.