Many members do not take the same dose of levothyroxine every day.
A typical example is alternating 50 and 75 micrograms in order to average 67.5. Or 75 and 100 to get 87.5. Or 100 and 125 to get 112.5. Or even 50 and 100 to get 75.
We also see some patterns such as a higher (or lower) dose on Saturdays and Sundays, or three or four days a week. I consider all these regimes questionable. They often seem to have been chosen to make the life of the prescriber easier. Or because the prescriber thinks we are unable to cope with more even patterns or tablets splitting.
In particular, three or four days a week on a higher dose seem odd to me. You inevitably end up with two consecutive days on the lower, or higher, dose. It would probably make more sense to dose alternate day for 7 days in each fortnight - with hardly any difference in total dose.
Personally, having alternate day dosed for some considerable time, I realised it didn’t suit me. I used to split the 25 microgram tablets so as to take 112.5 every day. And would do so again, if needed, to end up taking the same dose every day.
To get to the point of this blog! The trouble I want to discuss is testing. Taking a simple 50/75 alternate day dosing regime as the example, do you get your blood tested on a day you took 50? Or 75?
And precisely what effect does that decision have on TSH, Free T4 and Free T3? The answers are not immediately obvious - though we can expect the Free T4 to be a bit higher if the last dose was a higher dose. Effects on TSH and Free T3 levels are somewhat more subtly affected by levothyroxine dosing.
And can you achieve that consistently into the future?
Of course, there are the usual issues of how many hours after your dose to do the blood draw, but if you are alternating, you now ALSO have to consider whether that dose was a low or high dose!
I don’t think there is a satisfactory answer to this conundrum.
Either ensure you take an even dose every day. (At least for several days before testing.) Or accept that the effects on your results could be somewhat unpredictable.
