Agree that it's not a big deal, but if you read the insert that comes with your medication, it will tell you that you should never double up on a missed dose. If you realize within a few hours that you didn't take a medication, go ahead and take it, but if it's closer to time for the next dose, just skip the missed one and take the next one as scheduled.
Because levo takes so long to enter your blood, it's not a problem, but you might not be so lucky with other medications.
Its hard to tell with a T4 medication, but I would not "Double Dose" at all, one day missed will not hurt you, just take the normal dose the next day not double. Regards FTB4
Possibly, but generally, no. There is a long lag between administration of the meds and lab readings. It is a bad idea to take a "double dose" of thyroid medication.