when to stop NDT and how long to fast before bl... - Thyroid UK

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when to stop NDT and how long to fast before blood test?

BexyLS profile image
10 Replies

Hi guys,

I'm seeing a specialist on Wednesday and wanted to double check on what time I should stop taking Armour and eating to ensure any blood tests come out OK? My appt isn't until 1.30pm but want to make sure i get a good reading for thyroid not so bothered about blood sugar as i get this checked regularly. I know some say take last dose the day before and wait till after. I have asked before but can't find my questions and answers in the forum. Thanks! :)

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BexyLS
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Clutter profile image
Clutter

Stop taking Armour 24 hrs before you have bloods drawn & take after the draw. TSH is highest very early in the morning and probably at its lowest at 13.00.

Click on your user name to see your activity healthunlocked.com/user/BexyLS

ps there appears to be conflicting evidence as to whether fasting or non-fasting affects TFT.

BexyLS profile image
BexyLS in reply to Clutter

Thank you

shaws profile image
shawsAdministrator

Clutter is right about timing as your TSH wont be so high at 1p.m.

Clutter profile image
Clutter in reply to shaws

Thank you x

BexyLS profile image
BexyLS in reply to Clutter

It's ok as the Doc Im seeing uses FT4 FT3 and RT3 too. It's why i decided to see her as GP goes by TSH ONLY (grrr)

BexyLS profile image
BexyLS in reply to shaws

It's ok as the Doc Im seeing uses FT4 FT3 and RT3 too. It's why i decided to see her as GP goes by TSH ONLY (grrr)

rjb112 profile image
rjb112 in reply to shaws

"your TSH wont be so high at 1p.m."

Do you have an article you can link, that discusses this subject (the fluctuation in TSH due to the time of day)?

thanks very much

shaws profile image
shawsAdministrator in reply to rjb112

Excerpt:

"Key Findings

TSH levels were lower in the afternoon compared to morning values in 41 of the 42 participants. Median TSH in the subclinical hypothyroid group was 5.83 mU/L in the morning vs 3.79 mU/L in the afternoon (P<0.001). Median TSH in the primary hypothyroid group taking L-thyroxine was 3.27 mU/L in the morning vs 2.18 mU/L in the afternoon (P<0.001) Using the current reference range of TSH (0.4–4.0 mU/L), an afternoon blood sample would lead to a missed diagnosis in 50% of those with subclinical hypothyroidism (P<0.0001). Per participant, the range of TSH variability reached highs of 73% in the SH group and 64.7% in the PH group.

naturalmedicinejournal.com/...

If you have a question, seeing this thread is five years old, a person may have left the forum and you may not have had a response.

It's always best, if on an older post to put up a fresh question and then it will not be missed.

rjb112 profile image
rjb112 in reply to shaws

Thanks very much shaws. That was an excellent article that you referenced. From this preliminary info, it looks like TSH peaks between 2 am and 4 am......and is at its lowest level between 4 pm and 8 pm. I wish I had known this a long time ago! Very good info. Next I would like to find out the circadian rhythm, or the natural zenith and nadir, of free T4 and free T3. That's the other side of this, to complete the picture. Because I always plan to not only test TSH, but free T4 and free T3.....and when I make a case before my primary care doctor, to try and get her to change the way she is managing my thyroid....I want to present all the evidence.

Muffy profile image
Muffy

Around 8 - 8.30am would be the best for your blood test.

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