I have hypothyroidism and normally take 100 mcg of levothyroxine daily. However, my T4 is usually towards the low end of normal, like around 1.0, and my TSH tends to be high, like 8 to 10. A while back, my endocrinologist raised my dosage to 112 mcg daily, but on that dose I kept losing weight despite eating as much as I could stand (which is a lot!). At the next appointment, he suggested that I go back to 100 mcg but start taking an extra tablet one day a week. I said OK, but I haven’t actually been doing that because it seems to me (based on absolutely no knowledge of pharmacokinetics) that (a) taking 800 mcg per week would be equivalent to 800/7 = 114 mcg per day, which is even higher than the 112 mcg dose that gave me trouble, and (b) despite the smoothing effect from levothyroxine’s long half life, my T4 would still spike to some extent every time I took the extra dose. Any feedback as to whether those conclusions are accurate? (Obviously the normal thing to do would be to ask the prescribing doctor, but he’s a strange one, and I’m not planning to go back.)
What did your labs actually show while on the 112 mcg dose? It would be very unusual to be so sensitive to such a tiny change in dosage, particularly if your TSH was at almost 10.
Regarding the rest of the conclusion, you are correct regarding the cumulative weekly dosage concept. Some clinicians even have their patients simply take their cumulative dose once per week.
Unfortunately there aren’t any labs from the period when I was taking 112 mcg, as I had already gone back to 100 mcg on my own before the doctor suggested it. And now I’m perplexed, because it sure seemed like my weight was inversely tracking with my levothyroxine dosage, but maybe it was a coincidence. Anyway, many thanks for the feedback!