You may find this case report interesting concerning a case of Hamburger Thyrotoxicosis.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC183292/

The woman in question had recurring episodes of hyperthyroidism.

A 61-year-old woman with a history of recurrent episodes of transient thyrotoxicosis presented in November 2001 with a 3-week history of weight loss of 4 kg, palpitations and increased sweating. She had mild tachycardia (112 beats/minute) and fine tremor of the hands. She had no thyroid enlargement, thyroid bruits, eye signs or pretibial myxedema. A clinical diagnosis of hyperthyroidism was confirmed by elevated free thyroxine (T4) (46 [normally 9 to 23] pmol/L) and suppressed thyroid-stimulating hormone (TSH) (0.02 [normally 0.35 to 5.0] μIU/L). Her symptoms resolved spontaneously and her free T4 returned to normal (12 pmol/L) within 8 weeks.

The probable cause was identified as their raising their own livestock and having it butchered locally.

Further questioning into the patient's dietary history revealed that she lived on a farm with her husband and that every couple of years they slaughtered a cow from their herd, which was their main source of meat. Inquiries to the couple's local butcher revealed that he was unaware of the prohibition against gullet trimming (a procedure whereby muscles from the bovine larynx are harvested) and had inadvertently been contaminating edible meat with thyroid tissue. He used meat from the neck of the patient's cows to make patties, which were usually consumed by the patient within a couple of months of butchering. Her husband, who was not affected by any thyroid problems, did not consume these patties, preferring other cuts of meat.

Apparently this is not an unknown cause of temporary hyperthyroidism and is the reason thyroid glands are kept out of the food supply.

Community-wide outbreaks of thyrotoxicosis caused by the consumption of bovine thyroid gland in ground beef in Minnesota, South Dakota and Iowa10,11 in 1984 and 1985 resulted in the prohibition of gullet trimming in all plants that slaughter cattle and pigs. This case emphasizes that sporadic cases of recurrent thyrotoxicosis caused by consumption of thyroid-contaminated beef may still occur and may be diagnosed as silent thyroiditis. For patients with features suggestive of silent thyroiditis, health care providers should consider this cause of hyperthyroidism, especially for anyone who may be slaughtering farm animals for their own use and for hunters who may be gullet trimming game.

Eating more than tiny amounts of thyroid gland may not be a good idea.

Don't bother with thyroid, it is so tiny, no butcher will ever find it. Unless the butcher is a surgeon or the animal is large such as bison. I've eaten bison thyroid a few times, all raw. No effect what-so-ever. If you can get smaller whole animal such as lamb/mutton or deer then you can eat it all. Otherwise stick with larger organs like liver, kidneys, brains, spleen, and pancreas. They have everything you need.

It's known as sweetbread - as is the pancreas.

Be very very careful eating thyroid. As you may have experienced eating dessicated thyroid, if you are not used to it the side effects can be scary. It is something that you have to build up in your system. If your thyroid is fine though, I would recommend leaving well enough alone...

If you have hypothyroidism, why not look into "Armour" thyroid medicine which is made from pig's thyroid (my understanding - I'm not a doctor).