I may have messed up my bloods?

Hi all. Do you think this will have affected my blood test? I forgot to take my levo the day before my blood test in the morning as usual ( I then took it at 11am when I remembered ). Because I had heard that if you have a levels checking blood test you should take your levothyroxine the night before, I then took another tablet at midnight. I then didn't take the usual morning dose and went for the blood test. I am worried that this will affect the result. Anyone know please?

[jimh111]

The result will be fine. Levothyroxine has a long half life, about seven days. The only issue is that if you take levothyroxine a few hours before the blood test it can affect the test. Otherwise, the timing will only affect the result by a few percent, which is within the limits of accuracy of the assay.

[shaws Administrator]

If GP suggests lowering your dose tell him you've made a mistake.

[greygoose]

Actually, it's usually recommended that you leave a 24 hour gap between your last dose and the blood draw. I don't know where you heard about taking it the night before, that sounds a little strange. Do you normally take levo twice a day?

[Hidden in reply to greygoose]

No its usually 50mg once a day 6am. Which is why I thought I may have false result due to taking 50mg at 11am then 50mg at 12 midnight. But did not take the 50mg at 6am on the morning of the test

[greygoose in reply to Hidden]

Well, who knows. You took a double dose that day, which is rather strange. But, it depends if your doctor just looks at the TSH. I doubt it will have had time to affect your TSH, it's the FT4 it will affect, if at all.

Next time, just take your levo the day before as normal, and on the day of the test, take it after the blood draw. You do not have to take it at midnight!

[SeasideSusie Remembering]

Hidden No idea where you heard that you should take your Levo the night before a thyroid test.

The patient to patient advice here is to leave off Levo for about 24 hours (12 hours for T3). So your 11am dose of Levo the day before would have been fine, then your next dose should have been after the blood draw.

[SeasideSusie Remembering]

PS - snap greygoose

[greygoose in reply to SeasideSusie]