Testing procedure

[PrincessAnnie]

Hi I’m going to be testing my bloods on Monday the 4th of July and would like a reminder of the procedure please.

I take my T4 and T3 between 4-4.30 in the morning,I know not to take the meds on the morning of the test but I’m unsure about the T3 as if I recall right that’s different.

I’m planning on trying another vitamin b complex and was going to start it tomorrow but I’m sure I’ve read something about that too🤦‍♀️Any help would be gratefully appreciated as always👍

[SeasideSusie Remembering]

PrincessAnnie

Always advised here, when having thyroid tests:

* Blood draw no later than 9am. This is because TSH is highest early morning and lowers throughout the day. If looking for a diagnosis of hypothyroidism, an increase in dose of Levo or to avoid a reduction then we need the highest possible TSH

* Nothing to eat or drink except water before the blood draw. This is because eating can lower TSH and coffee can affect TSH.

* If taking thyroid hormone replacement, last dose of Levo should be 24 hours before blood draw, if taking NDT or T3 then last dose should be 8-12 hours before blood draw. Adjust timing the day before if necessary. This avoids measuring hormone levels at their peak after ingestion of hormone replacement. Take your thyroid meds after the blood draw. Taking your dose too close to the blood draw will give false high results, leaving any longer gap will give false low results.

* If you take Biotin or a B Complex containing Biotin (B7), leave this off for 7 days before any blood test. This is because if Biotin is used in the testing procedure it can give false results (most labs use biotin).

I take my T4 and T3 between 4-4.30 in the morning,I know not to take the meds on the morning of the test but I’m unsure about the T3 as if I recall right that’s different.

As you are doing your test on a Monday, this is how you should alter the timing of your T4 and T3:

Sunday: Delay your T4 until 24 hours before the test so, for example, if test is 9am on Monday you take your T4 at 9am on Sunday (24 hours before test).

Split your T3 into 2 or 3 doses, whichever can easily be achieved.

Take the first dose of T3 with your T4 at 9am.

Take your last dose of T3 between 9pm Sunday and 1am (8-12 hours).

Monday: Do not take any thyroid meds before test. Take them after your blood draw.

[PrincessAnnie in reply to SeasideSusie]

Thanks so much for this🙏Is there a reason why I should split my T3 dose,I’ll probably do the test about 8am.

[SeasideSusie Remembering in reply to PrincessAnnie]

Is there a reason why I should split my T3 dose,

Because T3 has a very short half life of 24 hours compared to T4 which has a half life of 7 days. Leaving 24 hours between last dose of T3 and test would give a false low FT3 result. Leaving 8-12 hours gives a measure of your normal circulating amount.

[PrincessAnnie in reply to SeasideSusie]

So if I’m doing my test at 8am I’ll take my T4 and first dose of T3 at 8am Sunday and I’ll take my second dose of T3 at 9pm Sunday is that correct?

[SeasideSusie Remembering in reply to PrincessAnnie]

First doses 8am Sunday.

Last dose of T3 between 8pm and midnight.

[PrincessAnnie in reply to SeasideSusie]

Great thank you so much you’re a star❤️

[PrincessAnnie in reply to SeasideSusie]

I’ve forgotten I’m early shift that day so would it be ok to take my test at 6am?

[SeasideSusie Remembering in reply to PrincessAnnie]

Yes as long as you leave the 24 hour gap since last dose of Levo and 8-12 hours for T3.

[PrincessAnnie in reply to SeasideSusie]

I did think that but just wanted to double check thank you😁