"Female Subject #2 excreted only 10% of the oral dose after one month of supplementation. She had the lowest baseline Iodine
level (0.022 mg/24 hr) and the greatest Iodine
retention after one and 30 days. The only distinctive feature of this subject was mammomegaly (size 40D). This would suggest a very important role of the mammary glands in the requirement for Iodine by the whole human body."
"Dr. Robert Rowen points out in Second Opinion for November, 2004, that breast tissue needs ten times as much iodine as the thyroid does, so it seems to make sense that with larger breasts you would need more iodine."
I have been large breasted since I was 10. Might be part of the equation.