This could be indirectly, as it mostly affect the thymus (cause shrinking) -and the endocrinal glands work together, connected; like the rest of us.
In your brother`s case I would stay loong away from this product, 1-3 months; see what happens. There are better options out there, if he needs a protein supplement.
Jumping into conclusion that Iodine caused different symptoms, I did so many times myself. But upon closer examination, quitting the Iodine for a week or two.. I found out it was other things.