In the US, most Graves’ Disease patients get herded into either radioactive iodine treatment (RAI treatment) or surgical thyroid removal. These are seen as “definitive” treatments, meaning permanent fixes. There is some truth to this as it is impossible to be hyperthyroid if you don’t have a thyroid. Taking anti-thyroid drugs, on the other hand, is seen as a temporary solution, usually for less than two years, before getting one of the “definitive” treatments.
Anti-thyroid drugs are, indeed, not definitive. 20-70% of Graves’ patients relapse after stopping medication. In that sense, these drugs don’t “cure” the disease, while the “definitive” treatments do.
However, after surgery or RAI, people usually become hyp-O-thyroid (too little thyroid hormone) and have to take supplementary hormone. The choice, from the patient’s perspective, is then either a lifetime of taking an anti-thyroid drug (such as methimazole, tapazole, or polythiouracil), or a lifetime of taking a “pro”-thyroid drug, such as Synthroid, Levothyroxine, or Armour.
If you have to take a pill every day no matter what, what’s the difference?
The antithyroid drugs have some minor side effects (rashes, headaches) as well as some rare, but very scary ones, such as agranulocytosis (loss of your white blood cells), problems with blood clotting, and death of liver cells. The “pro”-thyroid drugs have fewer serious side effects (possibly a slightly increased chance of osteoporosis, some digestive upsets). However, the risks of the “definitive” treatments themselves are worth considering. RAI is thought to strongly increase your risk of developing Graves’ Opthlamopathy, an eye disorder. Surgery and anesthesia have numerous inherent risks.
One solution that is common in Europe, but less so in the US is just staying on the anti-thyroid drugs permanently. This eliminates the risks of surgery or RAI, has the same impact on the daily life of patients (one or two pills a day), and, as long as you tolerate the drugs and don’t develop the nasty side effects from them can, presumably, be taken indefinitely.
The study I’m discussing today tests that last assumption – is taking methimazole as a long-term treatment safe and effective?
The authors started with 504 patients who were treated with methimazole for 18 months, after which treatment stopped but the patients were monitored. 104 patients’ hyperthyroidism returned within a year. Of these, the authors randomly treated half with RAI and half with more methimazole. They then followed these patients for 10 years and measured many indicators of their health, including liver enzymes, cholesterol, bone density, thyroid hormones, and cardiac tests (among others).
After 10 years, they found that the groups had similar thyroid levels, similar cost of treatment (from the perspective of the health care system) and many similar blood values. The RAI group had slightly higher LDL (“bad cholesterol”) levels, slightly lower bone densities, and similar cardiac tests. However, the methimazole group had more goiter and higher anti-thyroid antibody levels. The authors concluded that long-term use of methimazole was a good alternative to surgery or RAI. They say:
“Except for mild side effects, serious reactions are rare, and the risks of occurrence of cardiac and bone complications are equal to or less than those of radioiodine therapy…[A] possible approach to the therapy of hyperthyroidism may be to control the disease, for a lifetime, with antithyroid drugs. The remarkable lack of MMI side effects and the apparent high treatment compliance in this study prompt the adoption of an alternative approach such as this.”
End result? As long as you tolerate it (and most people do), long-term use of methimazole is a decent alternative to RAI or surgery.
Objective: To investigate the long-term effects of continuous methimazole (MMI) therapy. Design and methods: Five hundred and four patients over 40 years of age with diffuse toxic goiter were treated with MMI for 18 months. Within one year after discontinuation of MMI, hyperthyroidism recurred in 104 patients. They were randomized into 2 groups for continuous antithyroid and radioiodine treatment. Numbers of occurrences of thyroid dysfunction and total costs of management were assessed during 10 years of follow-up. At the end of the study, 26 patients were still on continu- ous MMI (group 1), and of 41 radioiodine-treated patients (group 2), 16 were euthyroid and 25 became hypothyroid. Serum thyroid and lipid profiles, bone mineral density, and echocardiography data were obtained. Results: There was no significant difference in age, sex, duration of symptoms and thyroid function between the two groups. No serious complications occurred in any of the patients. The cost of treat- ment was lower in group 1 than in group 2. At the end of 10 years, goiter rate was greater and antithyroperoxidase antibody concentration was higher in group 1 than in group 2. Serum cholesterol and low density lipoprotein-cholesterol concentrations were increased in group 2 as compared with group 1; relative risks were 1.8 (1.12–2.95, P,0.02) and 1.6 (1.09–2.34, P , 0.02) respectively. Bone mineral density and echocardiographic measurements were not different between the two groups. Conclusion: Long-term continuous treatment of hyperthyroidism with MMI is safe. The complications and the expense of the treatment do not exceed those of radioactive iodine therapy.
Azizi, F. (2005). Effect of long-term continuous methimazole treatment of hyperthyroidism: comparison with radioiodine European Journal of Endocrinology, 152 (5), 695-701 DOI: 10.1530/eje.1.01904