Synthroid and no iodine?

My friend recently had her thyroid removed along with a rather large pre-cancerous tumor. She was told to cut ALL iodine out of her diet and as even stopped using iodized salt and to take any other minerals hours apart from her Synthroid. I know iron can interfere with absorption but why was this extreme directive given? Iodine is used by more than just the thyroid. I am alarmed and puzzled.