I don't know really, but I've experienced the symptoms you describe. See these quotes from Ray's interview with Mary Shomon (2000):
"Occasionally, a person with a goiter will temporarily become hyperthyroid as the gland releases its colloid stores in a corrective process. Some people enjoy the period of moderate hyperthyroidism, but if they find it uncomfortable or inconvenient, they can usually control it just by eating plenty of liver, and maybe some cole slaw or raw cabbage juice. Propranolol will slow a rapid heart. The effects of a thyroid inhibitor, PTU, propylthiouracil, have been compared to those of thyroidectomy and radioactive iodine. The results of the chemical treatment are better for the patient, but not nearly so profitable for the physician.
Besides a few people who were experiencing the unloading of a goiter, and one man from the mountains of Mexico who became hypermetabolic when he moved to Japan (probably from the sudden increase of iodine in his diet, and maybe from a smaller amount of meat in his diet), all of the people I have seen in recent decades who were called “hyperthyroid” were not. None of the people I have talked to after they had radioiodine treatment were properly studied to determine the nature of their condition. Radioiodine is a foolish medical toy, as far as I can see, and is never a proper treatment."
"Occasionally, a person with a goiter will temporarily become hyperthyroid as the gland releases its colloid stores in a corrective process. Some people enjoy the period of moderate hyperthyroidism, but if they find it uncomfortable or inconvenient, they can usually control it just by eating plenty of liver, and maybe some cole slaw or raw cabbage juice. Propranolol will slow a rapid heart. The effects of a thyroid inhibitor, PTU, propylthiouracil, have been compared to those of thyroidectomy and radioactive iodine. The results of the chemical treatment are better for the patient, but not nearly so profitable for the physician.
Besides a few people who were experiencing the unloading of a goiter, and one man from the mountains of Mexico who became hypermetabolic when he moved to Japan (probably from the sudden increase of iodine in his diet, and maybe from a smaller amount of meat in his diet), all of the people I have seen in recent decades who were called “hyperthyroid” were not. None of the people I have talked to after they had radioiodine treatment were properly studied to determine the nature of their condition. Radioiodine is a foolish medical toy, as far as I can see, and is never a proper treatment."