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Sorry another query on test results

Blood test taken on 13/11/18 at 3:30pm.

Had I know they were going to test my thyroid I would have requested an early morning appointment and not taken my levothyroxine 100mg that on the day of the test either.

Tests results are:-

Serum TSH level 0.09 mu/L [0.35 - 3.5]

Below low reference limit

Serum free triiodothyronine level 3.9 pmol/L [3.8 - 6.0]

Serum free T4 level 17 pmol/L [8.0 - 21.0]

Blood test taken on 10/07/2018 at 8:30am

I booked the earliest appointment they had and missed my morning dose of 100mg of Levothyroxine until after the blood test was taken.

Serum TSH level test and the results were:-

Serum TSH level 0.74 mu/L [0.35 - 3.5]

As you can see my serum TSH level was within range in July 2018 but out of range in November.

As a consequence the GPs receptionist called me this morning and said my November blood tests were too low and they have already written a new prescription for 75mg Levothyroxine.

As I feel absolutely fine at the moment I told the receptionist that I wasn’t happy lowering the dosage, stating what everyone recommends in the group "having a blood test early morning and delay taking the Levothyroxine on the day until after the blood test is taken, otherwise the results aren’t accurate". She said she will type a note to that effect and see what the GP says.

I should also add that I have been tested positive for Autoimmune Thyroid Disease or Hashimoto's disease as it’s commonly referred to on here.

I would just like to know if anyone else thinks I’m right in asking to remain on 100mg Levothyroxine.

Thank you.

Steve

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Stevews

I would just like to know if anyone else thinks I’m right in asking to remain on 100mg Levothyroxine.

Serum free triiodothyronine level 3.9 pmol/L [3.8 - 6.0]

Serum free T4 level 17 pmol/L [8.0 - 21.0]

Absolutely right to stay on 100mcg (not mg) Levo.

Point out to your GP that your FT4 is 69% through it's range but your FT3 is only 4% through the range. As T3 is the active hormone and is made by some T4 converting to T3, then you have virtually no active hormone, as shown by your FT3 result, and your conversion is poor, in which case not only should you not have your Levo reduced but you would benefit from the addition of T3.

Two articles to help back you up in your discussion, both by Dr Anthony Toft, past president of the British Thyroid Association and leading endocrinologist

1) in Pulse Magazine (the magazine for doctors)

"The appropriate dose of levothyroxine is that which restores euthyroidism and serum TSH to the lower part of the reference range - 0.2-0.5mU/l.

In this case, free thyroxine is likely to be in the upper part of its reference range or even slightly elevated – 18-22pmol/l. Most patients will feel well in that circumstance.

But some need a higher dose of levothyroxine to suppress serum TSH and then the serum-free T4 concentration will be elevated at around 24-28pmol/l.

This 'exogenous subclinical hyperthyroidism' is not dangerous as long as serum T3 is unequivocally normal – that is, serum total around T3 1.7nmol/l (reference range 1.0-2.2nmol/l)."

Total T3 isn't normally tested, so you look at the FT3 result instead as that measures the Free T3 (unbound) rather than the Total T3.

You can obtain a copy of the article by emailing Dionne at

tukadmin@thyroiduk.org

print it and highlight question 6 to show your doctor.

2) Dr Toft now says that some patients benefit from the addition of T3

rcpe.ac.uk/sites/default/fi...

2 likes
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Hello SeasideSusie,

Many thanks for your quick and comprehensive reply.

I will definitely take onboard your advice and as suggested, request that I remain on 100mcg Levothyroxine (thought it was mg, like so many of my other tablets!) and will look into the reference material you’ve suggested above. I will also show the GP the printout, question6, once I receive a copy from Dionne.

It’s brilliant to be a member of this group otherwise you feel so alone and under informed.

Thanks again

Steve

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Hi Susie,

I’ve written to my GP about my thyroid results as well as outlining the facts and advice you’ve kindly mentioned.

I’ve tried for ages to work out the maths you applied to my results to get the range percentages.

Would you please put me out of my misery and tell me how you applied the maths to get to the percentages?

Also, in case he asks, what in your opinion is a good range to be in, percentage wise?

For example my FT4 is at 69% in range, is that good or average? What would be the optimal percentage for FT4 and FT3?

Hope that makes sense.

Thanks

Steve

Reply

Steve

Also, in case he asks, what in your opinion is a good range to be in, percentage wise?

We are all different in where "good" is for us as an individual. See Dr Toft's article where he says

"The appropriate dose of thyroxine ............. free thyroxine is likely to be in the upper part of its reference range or even slightly elevated"

Some people are fine when their FT4 is in the upper third of the range, others in the upper quarter. It's something we find out as we go along, which is why it's important to keep a record of all our test results, with ranges, use percentages if the ranges differ, make notes of dose of Levo and how you fee. Also ensure tests are done under the same circumstances every time, ie leave off Levo for 24 hours, fast overnight, drink water only until after the blood draw.

Your FT4 is about average, your problem is, as mentioned, your poor conversion of T4 to T3.

I've also sent you a PM.

Reply

Thanks again for the great advice and quick response. I’ve also taken a look at your PM and now I understand how you arrived at the percentages.

I will definitely, in the future, try and keep to a standard time for bloods being drawn, bear in mind what you’ve said about fasting, not taking Levo etc and keep a record of my results, and how I feel etc.

Thank you again.

I hope you are feeling well and your thyroid treatment is going well too.

Steve

1 like
Reply

The different timing of taking the levo and having the blood taken will make a small difference to fT4 and TSH. Having the blood taken later in the day will give a lower TSH but I don't know if this makes any difference when TSH is low. My guess is that these factors might halve your TSH at best. So, the majority of the drop in TSH is probably due to other factors, perhaps being on the levothyroxine for longer.

In any event your fT4 was very reasonable for someone on levothyroxine, certainly not high. You need to get your doctor to take full account of your signs and symptoms and not focus on TSH. TSH has its uses but patients and doctors alike are too obsessed with it, by attempting to get 'good' TSH results we are elevating it's importance and kidding the doctors into thinking it is an infallible marker.

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"Having the blood taken later in the day will give a lower TSH".

isn't it just the opposite?

The longer you wait to have the blood test, the higher the TSH will be, and the lower the free T4 and free T3 will be.

so if you wait even longer than 24 hrs between the time of your last Synthroid dose and the blood test, the TSH will be higher and the free T4 and free T3 will be lower, yes?

The pituitary secretes TSH telling the thyroid to make thyroid hormones.......so the longer it has been since you took your Synthroid, the higher your TSH should be, and the lower the free T3 and free T4.

appreciate your reply, thanks very much

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I just want to thank everyone for taking the time and effort to give me a reply, it’s much appreciated.

I must confess I really didn’t have a clue about the test results, what they mean and when they should be taken with or without Levo.

Having reread the replies it’s clear that in my case I did benefit from taking the early morning dosage of Levo and having an afternoon blood test.

I read so many times on the this forum how important it is to have bloods taken early morning and without Levo, that I thought it would have been in my best interest to have the same.

However, now I know having it done at that time is when your TSH is at its lowest and in my case that was low anyway.

I’ll press ahead though and argue to remain on the 100 Levo.

Thanks again

Steve

Reply

You did not benefit, TSH does not react that quickly to changes, however it does follow a circadian rhythm. This means it is naturally highest early in the morning as our metabolism increases ready to come out of sleep mode and have the energy and motivation to ‘go hunting’ this then gradually drops off - our bodies are basically still reacting as if we were hunter gatherers and why we recommend testing by 9 at the latest. That natural change can be the difference between getting a raise, a cut or being just in range so that out GP leaves our dose alone. If you were to skip a couple of doses before testing, you could tank your FT3 and FT4 but your TSH would take too long to reflect the change.

Your FT4 and FT3 are the ones that are affected most by the late testing as that means they were measuring the spike caused by taking the levo not your ‘operating levels’. To be truely comparable testing should be taken as close to the same time as possible each time. Your true results if taken early may potentially have put TSH in range, FT4 bottom range and FT3 below range - and no knicker fit by GP about dropping and a knowledgeable one might even have given a slight increase.

Reply

Steve

My head's not very well today, and I'm not sure I completely understand what you're saying here

Having reread the replies it’s clear that in my case I did benefit from taking the early morning dosage of Levo and having an afternoon blood test.

I read so many times on the this forum how important it is to have bloods taken early morning and without Levo, that I thought it would have been in my best interest to have the same.

If you want an increase in Levo dose, or to avoid a reduction in dose, then you need the highest possible TSH. TSH is highest early morning and lowers throughout the day. See first graph in this post which shows TSH is highest at midnight and lowest at 1pm

healthunlocked.com/thyroidu...

[It can also lower after food.]

So if you want to stay on the same dose or want an increase, an early morning blood draw will give the highest TSH.

So your 3.30pm blood draw gave a lower TSH than your 8.30am blood draw, which is what is expected.

As for taking Levo, this affects the FT4. If you take your Levo too close to the blood draw, the result will reflect the dose taken and be higher than your normal circulating amount of hormone, thus giving a false high. This is why it's suggested that we leave 24 hours between last dose of Levo and blood draw.

[And for anyone taking T3, there is nothing left in the blood after 12 hours after taking a dose, so it's advised to leave between 8-12 hours after last dose and blood draw. Any closer than 8 hours and that dose is reflected in the result and gives a false high, any longer than 12 hours and there's nothing left in the blood and gives a false low.]

Reply

Hi SeasideSusie,

I’ve looked at your reply above and you’re right, my levels would have been higher earlier in the morning than in the afternoon. Especially as I had eaten a two course meal before having the blood drawn. I don’t normally eat as anything during the day, no breakfast, or lunch only a evening meal.

I take Morphine and Fentanyl as well as tramadol throughout the day and that puts me off food completely.

Anyway, I’m somewhat more coherent in the mornings than I am in the afternoons. Most people would probably understand why, as I do take quite a large amount of opioids.

So thank you again for stating what I originally thought was true but for some reason got it completely back to front.

You guys deserve a medal for giving us sound advice. My GP never explains anything.

In fact, you are more knowledgable than most of the GPs I’ve ever seen about my thyroid. I’ve never seen an Endo and I don’t suppose they are any better either, going by some reports on here, which is why I’ve never pushed to see one.

Thanks again for all your time and effort.

Steve

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"Having the blood taken later in the day will give a lower TSH".

I was referring to the circadian variation in TSH which is at a maximum during the early hours of the morning. Leaving a few extra hours between taking levo and taking the blood will cause a rise in TSH but this is small compared to the circadian effect which would be about 20% between 8 am and 2pm academic.oup.com/view-large... . Sorry for the confusion.

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Thanks very much jimh111

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