Thyroid testing

[Jillkh]

Hi All.

I want to have a full thyroid test, including reverse T3. Can anyone advise who to go with and what I need to include please. I am in UK

Thank you

[pennyannie]

Hello Jillkh :

If you go into Thyroid UK who are the charity who support thi forum you will find a page showing a list of private companies who can action the blood tests for you, some even offer a nurse home visit to draw the blood.

If taking any supplements refrain from these for around week before hand so we get to see what your body is actually holding onto and fast overnight, just taking in water and get as early as possible morning appointment.

If taking thyroid hormone replacement - T4 - Levothyroxine - delay your morning dose until after the blood draw - it will not matter - T4 is a storage hormone - so do not worry.

Best to go for an appointment at the beginning of the week, if you can, so the turn around of the blood sample misses the weekend and hanging around in the system.

P,S, Just looked back : if taking NDT the suggestion is to leave around 12 hours from last dose to blood draw - do you split your dose ?

If I'm wanting a result to " fall into range " I'd need to leave longer than this :

The blood tests and ranges were not designed for NDT but for Big Pharma's synthetic versions of T3- Liothyronine and T4 - Levothyroxine alternatives :

[Jillkh in reply to pennyannie]

Thank you. That is really helpful .

[SlowDragon Administrator]

Just stop taking any supplements that contain biotin a week before blood test….eg vitamin B complex

What vitamin supplements are you currently taking

Little point testing RT3…..very expensive test

Unlikely to have high RT3 unless just on high dose levothyroxine taking Ft4 over top of range

Always test as early as possible in morning before eating or drinking anything other than water

Day before test split NDT into 2 or 3 smaller doses, taking last dose 8-12 hours before test

List of private testing options

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 by DIY fingerprick test

bluehorizonbloodtests.co.uk...

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/

NHS easy postal kit vitamin D test £29 via

vitamindtest.org.uk

[Jillkh in reply to SlowDragon]

Thank you that’s really hekpfuk

[jimh111]

Do you really want a rT3 test? It's very expensive, takes several weeks as the sample has to be sent away to a specialist lab and the results are not much use. Reverse T3 will be high if you are on high dose levothyroxine or have a concurrent illness. You will know if this applies to you so the rT3 result will not be of any use.

Reverse T3 does not affect thyroid hormone action although it does impair type-2 deiodinase (T4 to T3 conversion), the fT3 result will better reflect this. I would save time and money and not bother with an rT3 assay.

[Jillkh in reply to jimh111]

Thank you. I was thinking about reverse t3 as I guess I am desperate. I have been really well on NDT and suddenly ( after having Covid) my health has dived and I think that Covid has done to something to my thyroid and I am gaining weight rapidly

[Me1157]

Good for you having a reverse T3 test. Not many ppl understand that if you have too much reverse T3 in your system it can give a false result of your T3 levels. On the standard full UK thyroid panel you can't tell the difference between reverse T3, and free T3. I get this done once in a while now, but used to have it done alot as your stress level can affect your bodies ability to convert T4 into T3. Your blood results might look good and you still feel like crap... why not google for the best price, as in the UK this one test is expensive.

[helvella Administrator in reply to Me1157]

On the standard full UK thyroid panel you can't tell the difference between reverse T3, and free T3.

Do you have any references or evidence for this?

The attached image shows a set of reference intervals in one paper. If rT3 and free T3 cannot be told apart, the whole paper falls down.

The values for rT3 are of the order of at least two thousand times those of free T3.

researchgate.net/figure/Rec...

A set of typical reference intervals for thyroid hormones

[Me1157 in reply to helvella]

Sadly yes, IMHO and from personal experience of having high levels of reverse T3 in the past. I was told our thyroid gland produces some T3, but most available T3 comes from the conversion of T4 and it's during this conversion that the body can produce too much reverse T3. which will mess with the results of the balance of T4/ T3/RT3 On standard thyroid T3 blood tests, the labs can't tell the difference between freeT3/RT3 as they look identical. That's why it's important if you have reverse T3 syptoms, that you get it checked out. Those that are already taking T3 probably don't need a reverse T3 test. Your body can make too much reverse T3 when you're very poorly, under a lot of stress, have adrenal gland, or mental health issues etc.

[helvella Administrator in reply to Me1157]

On standard thyroid T3 blood tests, the labs can't tell the difference between freeT3/RT3 as they look identical.

I have a problem with that.

First, the lack of clarity as to whether the rT3 test is measuring Total rT3 or Free rT3.

Second, at the 97.5% percentile, both TT3 and rT3 have the same numeric value. The implication of confusion (with rT3 looking like T3), being that the subject has zero Total T3.

Third, it also questions why anyone would put forward the idea of calculating/measuring an rT3/T3 ratio.

I wonder if diogenes would care to comment from his point of view?

[Me1157 in reply to Me1157]

I can only tell you about what I have experienced first hand. I don't have any links to studies etc. When I'm back in Florida, I can look through some of my old blood tests and upload them if you like. There is always an exception to every rule. That's why we're all on here right? To find out how things affect others in the real world.

[tattybogle in reply to Me1157]

I'm probably just misunderstanding what you've written , but i don't understand these comments ,and they seem contrary to what i have read about rT3. Could you explain what you mean in a bit more detail please? or give a reference for the source.

"if you have too much reverse T3 in your system it can give a false result of your T3 levels."

How does rT3 give a false fT3 result ?

"On the standard full UK thyroid panel you can't tell the difference between reverse T3, and free T3".

do you mean rT3 is included in the fT3 measurement ? , or some other meaning that i have missed ?

[Me1157]

From personal experience of having high levels of reverse T3 in the past. Our thyroid gland produces some T3, but most available T3 comes from the conversion of T4 and it's during this conversion that the body can produce too much reverse T3. On standard thyroid T3 blood tests, the labs can't tell the difference between freeT3.....and reverse T3 as they look identical. That's why it's important if you have reverse T3 syptoms, that you get it checked out. Those that are already taking T3 probably don't need a reverse T3 test. Your body can make too much reverse T3 when you're very poorly, under a lot of stress, have adrenal gland, or mental health issues, plus more.

[Jillkh in reply to Me1157]

That is really interesting. I have been doing fine on NDT for years. I got sick with a bad chest infection then Covid and even through that was weeks ago, my health has not recovered. I am gaining weight rapidly and have my old symptoms back

[Hidden in reply to Me1157]

On standard thyroid T3 blood tests, the labs can't tell the difference between freeT3.....and reverse T3 as they look identical.What is this statement based on? As far as I know free T3 and rT3 are measured separately.

[greygoose in reply to Me1157]

Totally agree with Hidden .

The rT3 test tests for rT3.

The FT3 test tests for Free T3.

The TT3 test tests for FT3 and bound T3 - i.e. total T3 blood content.

Pretty sure modern blood tests are capable of telling the difference between FT3 and rT3. But, if it were the case that you can't tell them apart, how would testing rT3 make any difference? Because if FT3 tests mix up rT3 and FT3, then rT3 tests would do the same. You can't have it both ways.

What do you mean by rT3 and FT3 look the same? To become rT3 or FT3 they had to have different iodine molecules removed, so how can they look the same? You can find diagrams to show you the difference - I'm afraid I've lost my link, so can refer you to one, but they exist.

And what are 'rT3 symptoms'? rT3 is inert, so doesn't cause symptoms. Any symptoms you are likely to have felt are due to low FT3, not high rT3.

[Me1157]

So sorry to hear that, perhaps COVID has triggered your thyroid? My hubby ended up with a heart condition after he had covid. You hear about ppl ending up with all sorts of issues due to covid. Lets hope it's temporary and your body will recover soon.