Thyroid dosing: Too low is too slow

I definitely learned that initiating thyroid replacement therapy in persons profoundly hypothyroid should be done slowly and carefully to avoid heart complications. I never learned, however, the proper starting dose for your average, semi-sluggish, hypothyroid woman. This is important as statistics suggest that 15% of adult women ultimately become low in thyroid.

Leaving no problem left unstudied, Dutch docs conducted a study that compared a full starting dose of levothyroxine (1.6mcg/kg which is the equivalent of a .1 mg Synthroid or Levoxyl tablet for a 130 pound woman) to a weensy, sissy little dose of .025 mg with respect to the speed with which thyroid levels returned to normal on follow-up testing.(1)

Whether or not the 50 study participants received the big deal or the teeny bit, no one complained of palpitations, chest pain, nor keeled over dead of a heart attack.

The notable difference between the two groups, however, was that nearly half the full dose group was euthyroid (normal levels) within 2 months of the study's start but only 3 in the low and slow bunch had achieved normalcy by then. In a way, it matters not one way or the other as quality of life with respect to symptoms improved at the same rate in both groups.

On the other hand, each dose adjustment requires a trip to the lab to check levels followed by 3 to 4 frustrating calls to the physician's office to get the results and get the new prescription called in, so aggressive dosing may work better for all in the short and long run.
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Roos A, et al. Archives of Internal Medicine 2005;165: 1714-1720.