At my recent (and very disappointing) meeting with an endocrinologist, I was told not to bother doing a D102 test, even though she hadn’t done any blood tests at that point! She even had the cheek to say I was wrong and Thyroid UK do not recommend them, even though their website clearly does!
I knew that my T3 levels have always been good, even prior to trialling T3 (I’ve been on levothyroxine for the majority of my adult life). But my question is, is it worth me doing the D102 gene test even though my T3 bloods are good, as my tissues may actually be depleted of T3?
I have tried T3 which I purchased privately, and didn’t feel much better, just lost some weight. But am still searching for answers, so wondered if it’s worth doing the gene test to have another crack with professional T3 guidance, and a free supply, or am I wasting my money?
Thank you for your advice.
Written by
CornishChick
To view profiles and participate in discussions please or .
You might want to do the test so that you understand your body better. It will add another piece to the jigsaw. That way you know whether you have the mutation or not.However if you do have the mutation you still may not be able to find an endo that understands and you still may not get lio on the NHS.
A little T3 comes from the thyroid (15% on average, more if TSH is high) but most comes from conversion of T4 mainly from D2. When on full replacement levothyroxine all the T3 comes from conversion, again mostly D2. Since D2 takes place within the cells the tissues that are dependent upon it are not being deprived of T3. Tissues that have little or no D2 activity will get their T3 from the blood. So, the DIO2 polymorphism test is not much use. Blood levels of T3 reflect conversion activity (and cellular T3) if you are on levothyroxine. (If fT4 is high most T3 comes from D1 and so fT3 isn't a good reflection of tissue T3).
However, ignoring the science. If someone has the DIO2 polymorphism it can enable physicians to rationalist prescribing liothyronine. So, on this basis the test can be useful. Of no scientific use but helps get a prescription.
This diagram shows the three deiodinase enzymes, what they do and where they are mainly located thyroidmanager.org/wp-conte... . It gets a bit complicated so just look at the top half, the bit with the arrows and the list of tissues they are found in.
Most T3 comes from D2 activity which takes place near the nucleus of cells. D2 controls local T3 in these tissues (especially the brain and skeletal muscles). The T3 produced in these cells finds it way into the blood, so D2 is the main source of blood T3.
Other tissues take their T3 straight from the blood. So some tissues 'make' their own T3 from T4 and other tissues just pick it up from the blood. The brain is most reliant on D2. The brain gets around 80% of its T3 by converting T4 to T3 with the D2 enzyme and it gets the other 20% from the blood.
So, if you are on levothyroxine only (and your thyroid is not working) all your T3 will come from conversion of T4 to T3. Since most of this conversion is done by D2 deep within cells you can deduce that if your fT3 is good you have good levels of T3 within the cells that rely on local conversion of T4 to T3.
That diagram makes good sense. Thanks. I struggle because the theory never seems to map onto me. Let me run my case past you and see if you have any idea what's happening, because something is far from right.
Years on Levo alone, no dose made me feel better. I was better without it at all back then but with a higher TSH over range but below 10. I have the Dio2 polymorphism from one parent. My conversion was always quite poor, despite constantly chuffing vitamin D, B12, Iron, magnesium etc for years!
Went to see a private endo. for help. He understood the Dio2 issue and said I needed some T3 adding. I had been ill for years and was desperate. I'd done all the right things and nothing had worked so I decided to trust his method. Mistake. His dosing method was odd. But I followed it. I do wonder if I had just held on at 10mcg for a few months if it might have worked but I moved past 10mcg fast.
Now, I am reducing Levo to see if that calms down the D3 which could be converting things to the wrong hormone. I am now on 55mcg T3 and 50mcg Levo. I don't feel like I take T3 at all. If I increase my dose by 5mcg I will feel much better for the day I increase it. This last increase up to 55mcg actually gave me 1.5 days of good and then I felt racy and a bit overdosed for half a day and then back to normal. When I increased and felt good my permanently high HR (I have permanent Afib) calmed down, reduced it's erratic behaviour too. My low temp went up. As soon as the effect wore off my HR went back up and more erratic and my temp dropped and I feel exhausted and depressed again.
That happens pretty much each dose increase. Any idea what's going on? My body seems to be blocking the T3. As it blocked the good effects of Levo.
So sorry, I forgot to reply to this. Fortunately I printed off your post as a reminder but only used the printer again today! Can't go into too much detail as this is CornishChick's post. It seems that as you increase your L-T3 it works until your body responds (as it should) and tries to eliminate some of the extra T3. You are taking enough hormone, especially T3 to overcome any conversion problem. Also, your tachycardia / AF mean you really don't want high hormone levels.
In terms of 'blocking the T3' I had this sort of problem which was due to disruption of T3 binding by endocrine disrupting chemicals (EDCs), substances that mimic thyroid hormone and disrupt T3 binding to receptors. I describe it on my website ibshypo.com/index.php/acqui... (click on the blue link at the bottom of each webpage to get to the next section). It's rather extraordinary but "WindEze" tablets which are safe and cheap contain a substance called simeticone which can remove EDCs from the body. It's worth doing a three month trial of simeticone to see it helps, the tablets available from any pharmacy would cost about £10 per month.
Interesting idea! Would never have thought of that. With the help of someone better at maths than I, I can now see that my ratio of T4/T3 has improved a lot and is now good. And this weekend I've had a lot of hard work to do, whilst I'm slow and have to sit down a lot, I have achieved a lot too. And I don't feel too bad, just tired and achey because I'd done things. I think this new dose is helping and rather unexpectedly the higher the T3 dose the better my HR and rhythm are getting. I think that's down to reducing the Levo. My rhythm gets well out of sorts if I get over-tired and need more T3. My BP is good. And for the first time in decades, my cholesterol level has just come back in the normal ranges with no flags. That's not happened before. I'm not overmedicated I now realise. I'm perhaps suffering from hormone resistance and so need to find out how to overcome it. You idea is worth a try perhaps.
Yes, I found I have to take two a day otherwise my brain gets very fuzzy. This happens when I sometimes forget to take them, so it’s a useful ‘blind’ trial. I think a small number of people are susceptible to this sort of endocrine disruption.
I would first seek to remove any furnishings that might contain PBDEs and damp dust or HEPA vacuum weekly and open windows for a brief while each day. This will help remove any endocrine disrupting chemicals from the home (and car). Essentially any soft furnishings from 2004 or earlier are problematic.
I would then try four a day for three months as a trial, they contain very small amounts of simeticone and this is within the recommended dose. Simeticone removes PBDEs very slowly. We absorb tiny amounts of PBDEs but because they have long half lives they build up in time. We only have about 30 mcg of T3 in our bloodstream so it only takes minute quantities of similar molecules to have a disruptive effect. If you find it effective you can experiment with a lower dose. If you should notice you are becoming a little hyper you should reduce your thyroid hormone dose quickly.
Sorry you had such a rubbish endo consultation. They could least be polite.
Anyway, if you had good FT3 levels before medicating T3 meds then you have adequate conversion abilities and don't require the DIO2 test to indicate otherwise.
Which begs the question if you had good T3 levels prior to medicating T3, then why are you medicating extra T3?
Thank you for your reply. Good question! It was something someone on here suggested. I was feeling tired and my T3 was in the upper range, but they suggested I took a little to see if it helped.
Content on HealthUnlocked does not replace the relationship between you and doctors or other healthcare professionals nor the advice you receive from them.
Never delay seeking advice or dialling emergency services because of something that you have read on HealthUnlocked.
Is having this DIO2 gene test done my only hope to get evidence that somerset ccg will accept I need t3
Is t4 absolutely necessary to take when on t3?
DIO2 faulty gene
Re: ?D102 test
Hypothyroid with High RT3 & Defective DIO2 Gene. On T3 only treatment. No improvements.
