Advice on when to stop taking T3 and T4 before blood draw

[1839]

Advice please, I am having a blood draw taken next week for Thyroid. The draw will be at 12.30 lunchtime. I am currently taking T4 at 7am, and T3 four times a day at 7am, 12noon, 5pm and 10pm. When should I take the last T4 and T3 before the blood draw please?

[fuchsia-pink]

TSH is generally lower at midday than with an early morning blood draw (which is why early morning is always recommended here) but I guess it doesn't make much difference when you take T3 meds which suppress TSH anyway ...

It's recommended here to have a gap of 24 hours from your levo and 8 - 12 hours from your last dose of lio - as this gives a good representative level of hormone rather than a just-taken-your-meds spike, and then being consistent with future blood tests - which means changing your timings a bit on the day before the blood draw unless you can re-book a test time that works better. If you keep the test time, can you take the lio at 12 noon, 5 pm and 12.30 am? And have a late lunch so the 7 am moved to 12.30 pm levo can be absorbed properly. Then have the next dose of both meds straight after the blood test

[1839 in reply to fuchsia-pink]

Hi fuchsia-pink. Thank you for your advice, all makes sense. I am unable to alter the time of the blood draw but can adjust times of taking medication to suit. Regards

[Goldengirl01]

It is best as early in the morning as possible with nothing to eat or drink before except for water then take your meds straight after. T4 should be taken 24hrs before bloods and t3 8/10 hrs before so you may have to alter your doses.this will show tsh at it highest and t4 at its lowest. Anything your taking with biotin should be left off for 7 days as the labs may use biotin in their testing. Any thing Iv forgotten someone will be able to tell you on here.

[1839 in reply to Goldengirl01]

Thank you, unable to alter the time of the blood draw, but advice very helpful, the only thing I have found biotin is methyl b complex.

[SlowDragon Administrator]

Ideally rebook for blood draw as early as possible in morning before eating or drinking anything other than water

Last dose levothyroxine 24 hours before test

Last dose T3 8-12 hours before test

What vitamin supplements are you currently taking

If taking any supplements that contain biotin you need to stop these a week before ALL blood tests

Important to test vitamin D, folate, ferritin and B12 at least annually

[1839 in reply to SlowDragon]

Hi SlowDragon. Unable to alter time of blood draw but your advice very helpful, I am on a number of supplements and the only one I have found Biotin in is methyl b complex. Note what you say about vitamin D, folate etc. Thankyou.

[SlowDragon Administrator in reply to 1839]

Yes, necessary to stop vitamin B complex a week before test