How to shrink a multi-nodular toxic goiter? I am taking iodine / selenium. I am vegan. Goiter has been slowly growing over the last 10 years. Currently about the size of a golf ball. My levels are t4 18.6, t3 (liothyronine) 6, tsh 0.01

Abnormal . your thyroid lab work is normal you need a face-to-face visit with an endocrinologist and appropriate testing and treatment of your thyroid you may have an overactive thyroid which can be very serious medical problem seek medical attention the next few days.
Thyroidologist. Hyperthyroidism is evident by virtue of these levels and is usually treated with either antithyroid medication like tapazole (methimazole) or radioactive iodine but the dose may be tricky because of the large size of the gland and the taking of iodine. This case requires the care of a thyroidologist or endocrinologist who has experience in such cases.