Thyroid blood test

[Suzi_]

I am scheduled to have a fasting blood test by my gp, I am going to combine my thyroid blood test too. My endo says that Levothyroxine/ synthroid 50 mcg taken in the am @ 7 am should not effect my labs and to skip Liithyronine/ cytomel 5 mg till after the test.

Usually I have my blood tested @3 pm after 8 hours of taking meds.

Do U think it would give me accurate results to have my thyroid labs at this time?

[SlowDragon Administrator]

Always get thyroid testing as early as possible in morning before eating or drinking anything other than water and last dose levothyroxine 24 hours before test

Last 1/2 or 1/3rd of daily T3 dose 8-12 hours before test

[Suzi_ in reply to SlowDragon]

Can’t split the 50 mcg dose. Should I skip taking Levo in the morning, day of the test? I can take both synthroid and cytomel after the labs is done.

[SlowDragon Administrator in reply to Suzi_]

Take 50mcg levothyroxine 24 hours before test

And 2.5mcg T3 at 8-12 hours before test

[Suzi_ in reply to SlowDragon]

I take my 50 mcg levo at 7 am, I will skip the t4 on the day of the test, labs r @ 10 am so that’s fine.

I would have to split my 5 mcg of T3 in to half and take it @ 10 pm before going to bed.

[SlowDragon Administrator in reply to Suzi_]

That will be good

[Suzi_ in reply to SlowDragon]

Thanks so much

[SeasideSusie Remembering]

Suzi_

Regardless of what your endo says, patient experience tells us that the most accurate results are with the following time gaps:

Levo - last dose 24 hours before blood draw

T3/NDT - 8-12 hours before blood draw.

Areyou having this test in the morning? That's when a fasting test should be done as it's easier to fast overnight and not have breakfast before the test rather than expect the patient to fast all day and have the test later in the afternoon thereby missing breakfast and lunch.

[Suzi_ in reply to SeasideSusie]

Yes, test is fasting @ 10 am

I thought Levo was T 3

[Suzi_ in reply to Suzi_]

Sorry, synthroid is T4, I got them mixed

[humanbean]

By having a blood test at 3pm you are getting it done at the time of day when your TSH is at its lowest.

TSH has a circadian rhythm - it changes naturally over a period of 24 hours. Since TSH is used by most doctors as the most important measure of thyroid function, hypothyroid patients need to get TSH showing up in a test as high as possible so that :

a) they increase their chances of getting diagnosed, if a hypothyroid diagnosis is necessary

b) they increase their chances of getting a raise in dose of thyroid hormones if one is necessary.

c) they decrease the chance of getting their dose reduced

See the graphs on this thread :

healthunlocked.com/thyroidu...