Metabolism Influence on Distribution of Radionuclides in the Body

Metabolically, radionuclides are handled in the same way as stable elements of the same atomic numher. Thus radioactive iodine simulates stable iodine, being concentrated in the thyroid gland so predictably that its rate of uptake provides an accurate measure of thyroid function. The metabolism of other radionuclides also is sufficiently characteristic so that their patterns of uptake, distribution, translocation, and excretion are similarly predictable. 

While the effects of internally deposited radionuclides are attributable in most instances to the type and energy of the radiations they emit, their transmutation on decay has also been implicated in certain circumstances, e.g., the severe mutagenicity and lethality caused by decay of iodine-125 in 5-iododeoxyuridine-labelled DNA is attributed in part to rupture of the uracil ring following transmutation of the iodine (Stocklin, 1979). 

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