Thyroid UK
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About to do a pinprick thyroid test- how important is it to do the test early morning as opposed to nearer the posting time please?

Hi, I'm currently having b12 injections and noticed on the last blood test my TSH has gone from 0.42 to 3.14 and f4 is 13. I know these are still in range, but I'd like to check the antibodies, just for peace of mind as a couple of other family members have thyroid problems, and would like to rule it out. My ferritin has also been low, and although rose from 12 to 140 with supplements last year, has now dropped down to very bottom of range since I'd stopped supplementing and vit d has been low. ( have started back on iron and trying folate too as that was 6 (3-15) So I thought I'd try a pinprick test to and also check ferritin, vit d, Crp, etc, as well as thyroid.I know it's best to do the test as near to posting as possible, but have also read that thyroid testing is best done first thing. Is this just because of TSH levels or does it affect other parts such as f4,f3 and the antibodies please? If it's just the tsh, I'd rather forego that and do it nearer to posting?

Also, can anyone tell me whether it is a good idea to include the reverse 3 as well with my results, or not necessary, due to the extra costs?

Any help very much appreciated , once again...

Thanks Jo

4 Replies

I always do my fingerpick test about 6.30am then post it that morning. I always try to do it on a Monday morning so that it doesn't lie in a post box for too long.


Thank you, our post doesn't go until much later in the day, but I could do some searching to see if there are any earlier posts further afield....



T3 like TSH goes high and low at different times of the day//night. It is usually recommended to have blood drawn early whilst fasting to ensure the highest TSH possible so avoiding a med reduction by an ignorant doctor. It is also good to test like-for-like to receive accurate test results.

As you are doing a private test it makes no difference when you test as long as you make allowances for the circadian rhythm.

Whilst wondering why your iron levels would drop so low, have you considered low stomach acid (caused by low thyroid hormone and possible adrenal issues) ? ? .... Supplementing Betaine with Pepsin may help a more normal iron absorption whilst taking supplements with 500-1000mg Vit C or Apple Cider Vinegar. When iron levels are low it slows down the conversion of T4 to T3 (deiodinase activity) as requires iron-containing-enzyme "thyroid peroxidase" to produce the thyroid hormones.

Testing RT3 is only good if you are prepared to look at the whole picture as the RT3 result is so multifactorial and complicated that most doctors//endos won't even entertain it.

Post all results complete with ranges (numbers In brackets) for members to comment.

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Many thanks for your reply. When you say as I'm doing a private one it doesn't make no difference when I test, can I ask what you mean please? And what do you mean making allowances for the circadian rhythm please?

Thanks for the info about iron helping with converting t4 to t3, didn't realise that. Yes, it could well be a stomach acid problem I guess, seeing as b12, iron and vit d are low and I have low body weight although I eat plenty! I'm taking vit c to help the iron absorption, but could try some apple cider vinegar. Ive read about its benefits in the past, but have had problems with candida overgrowth and been unsure as to whether it would worsen it. Have also been told I have low S igA levels, but the Dr has insisted that's not a problem?

Thanks once again...:)


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