Final answer:
The approximate amount of gadolinium that enters breast milk after intravenous administration to a lactating mother is about 0.04%, which is significantly lower than the options provided in the question. Gadolinium's oral bioavailability in infants is low, minimizing potential risks.
Step-by-step explanation:
The approximate amount of gadolinium that gets into breast milk after a mother receives IV gadolinium is b) 0.04%, which is not among the options provided but is the most accurate estimation according to the most recent studies.
Gadolinium is a contrast agent used in magnetic resonance imaging (MRI) to enhance the clarity of the images. When a breastfeeding mother receives intravenous gadolinium, concerns about its passage into breast milk and potential effects on the infant arise. According to the American College of Radiology and other research, the amount of gadolinium that is transferred into breast milk is extremely low, estimated at approximately 0.04% of the dose given to the mother. Moreover, the amount of gadolinium absorbed orally by the infant is much less because the bioavailability of gadolinium taken orally is very low, ranging around 0.01% to 0.04%.
This is due to the poor absorption from the gastrointestinal tract. Thus, while the choices provided do not represent the true value, they all vastly overestimate the transfer of gadolinium into breast milk. Research generally supports the notion that the risk to the infant from breastfeeding after maternal exposure to gadolinium is exceedingly small and that it is usually safe to continue breastfeeding after receiving such contrast agents.