Free T3 test

[Lilly12255]

Hi,

When is best to take the Free T 3 to get a reliable result?

Morning early? Later?

fasting?

Thanks

[diogenes Remembering]

Probably doesn't matter, if you don't get tested in the middle of the night, when FT3 levels mildly rise for a time.

[DippyDame]

Test close to 9am for highest TSH and along with at least FT4 and FT3.....full thyroid test if you can manage that.

No food or drink before test

12 hours after taking T3 or

24 hrs after levo

[SeasideSusie Remembering]

You're not thinking of doing a Free T3 on it's own are you? It should always be done along with TSH and FT4 and then our advice is as follows:

* Book the first appointment of the morning, or with private tests at home no later than 9am. This is because TSH is highest early morning and lowers throughout the day.

In fact, 9am is the perfect time, see first graph here, it shows TSH is highest around midnight - 4am (when we can't get a blood draw), then lowers, next high is at 9am then lowers before it starts it's climb again about 9pm:

healthunlocked.com/thyroidu...

If we are looking for a diagnosis of hypothyroidism, or looking for an increase in dose or to avoid a reduction then we need TSH to be as high as possible.

* Nothing to eat or drink except water before the test - have your evening meal/supper as normal the night before but delay breakfast on the day of the test and drink water only until after the blood draw. Certain foods may lower TSH, caffeine containing drinks 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, split dose and 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).

These are patient to patient tips which we don't discuss with phlebotomists or doctors.

[SlowDragon Administrator]

Looking at previous posts, presumably you have autoimmune thyroid disease also called Hashimoto’s as you have endometriosis

Important to test FULL thyroid and vitamin levels at least annually

what vitamin supplements are you currently taking

Are you on levothyroxine or levothyroxine plus T3?

Test early morning, ideally just before 9am…..and last dose levothyroxine 24 hours before test….and if on T3 …..split dose day before into 3 smaller doses spread through the day, with last dose approx 8-12 hours before test

List of private testing options and money off codes

thyroiduk.org/getting-a-dia...

Medichecks Thyroid plus antibodies and vitamins

medichecks.com/products/adv...

Blue Horizon Thyroid Premium Gold includes antibodies, cortisol and vitamins

bluehorizonbloodtests.co.uk...

If you can get GP to test vitamins then cheapest option for just TSH, FT4 and FT3

£29 (via NHS private service ) and 10% off down to £26.10 if go on thyroid uk for code

thyroiduk.org/getting-a-dia...

monitormyhealth.org.uk/

Monitor My Health also now offer thyroid and vitamin testing, plus cholesterol and HBA1C for £65 

(Doesn’t include thyroid antibodies) 

monitormyhealth.org.uk/full...

10% off code here 

thyroiduk.org/getting-a-dia...

Only do private testing early Monday or Tuesday morning. 

Watch out for postal strikes, probably want to pay for guaranteed 24 hours delivery 

[Goosle]

The day before blood test only take first dose ..take blood 18 to 24 hours after that first dose. Resume meds after blood test. I always do morning blood draw on an empty stomach.

[SeasideSusie Remembering in reply to Goosle]

Goosle

The day before blood test only take first dose ..take blood 18 to 24 hours after that first dose.

That is not the advice of this forum for T3. On the day before the test the full daily dose of T3 is taken, split into 2 or 3 whatever is convenient, and the last part of the dose should be 8-12 hours before testing. T3 has a half life of 24 hours so if you leave 18-24 hours then you get a false low FT3 result.

If taking Levo then last dose of Levo should be 24 hours before test.

[mjm1929]

can you please let me know what is T3 I have never had one please

[helvella Administrator Thyroid UK in reply to mjm1929]

Suggest you have a look here:

btf-thyroid.org/what-is-thy...

There is a video animation which is quite reasonable.