Tuesday, March 15, 2016

That Temperamental Thyroid Gland

Source for Figure 29 Cancer in Patients Treated for Hyperthyroidism: Dobyns, B.M., Sheline, G.E., Workman, J.B., Tompkins, E.A., McConahey, W.M. and Becker, D.V. Malignant and benign neoplasms of the thyroid in patients treated for hyperthyroidism: A report of the cooperative thyrotoxicosis therapy follow-up study. Journal of Clinical Endocrinological Metabolism, 38:976, 1974.

Most of our organs - like our hearts and kidneys - either work or they don't. Our thyroid gland, however, either can refuse to work hard enough (hypothyroidism), or can put out too many hormones (hyperthyroidism) - either of which can make life miserable. Those who are the victims of excessive thyroxin have several choices to reduce production of this hormone: whacking away at the thyroid with a scalpel, drugging it into submission, or introducing radioactive iodine 131 into the body, which rushes directly to the gland and essentially wounds it, thus decreasing its activity. [Iodine 131 is also used both for diagnosis of thyroid function and, in the case of a malignancy, "ablating" or "burning up" the organ. The latter procedure has made thyroid cancer probably the most successfully treatable of all malignancies.]

A study by B.M. Dobyns, et al. observed the prevalence of thyroid cancer incidence in 35,000 hyperthyroid patients out to twenty years after treatment. Some 1,200 of these were treated with drugs, with another 12,000 having undergone surgical treatment. The majority, about 22,000, were subjected to very high doses of 131I - on the order of 50,000 mrem or 50 cSv. One would logically expect rampant cancer in these individuals on the basis of the LNT. But it's (another) miracle! As Figure 29 indicates, not only did radiation not result in a high malignancy rate, but it seems to have had a hormetic aftermath. Gee, perhaps this can be explained by the "healthy patient effect."