I would like to concur with Dr. Newmans posting on the use of Iodine containing
radiocontrast agents.

While it is true they contain iodine,  the iodine is covalently bound to
benzene rings, and the manufactures' studies reinforce that virtually NO iodine
is metabolically released into the plasma(less than 0.005%), but rather rapidly
cleared renally with the molecule intact.  Hence,  it would be virtually
impossible for the iodine in radiocontrast agents to be released and then enter
milk.

Virtually all of these radiocontrast agents look alike, they differ slightly in
structure, but almost all have covalently bound iodine molecules in varying
concentration.

Their plasma half-lives are almost without exception less than one hour, and
they seldom leave the plasma compartment.  Their concentration in breast milk
has been found to be less than 0.5% of the maternal dose.

Further,  their oral bioavailability is nil, and we commonly use these same
agents orally in neonates as radiocontrast agents.

Remember, after 5 half-lives, about 99% of all medications are
completely cleared from the body.

Regards
Tom Hale, Ph.D.