Teen son starting Thyroxine

[Remmy123]

My son has to have Regular blood tests for another condition and these are full bloods- for a few years his T4 and TSH have been abnormal. He shows no symptoms of under active thyroid that I can see (does have delayed puberty) it is not autoimmune but they think best to start him on a low dose to see through puberty.

I am wondering what to expect seeing as no visible symptoms? We have thought in past he may have adhd now I'm wondering if it's brain fog?!

thanks

What's his TSH? Even at subclinical levels (ie not really 'bad' enough to treat) I felt like death, when it got really high I started Levothyroxine. Taken 18 months to get sorted but I feel invigorated.

Might find that he comes out of his brain fog, I certainly did.

Thanks so much

think ranges are different for children

his results are: Thyroid results: TSH 0.12 / T4 9.8

I went on it when subclinical, GP didn’t see the point in waiting to actually go under.
I found out because I couldn’t get pregnant, but I was pregnant 12 months after starting.

Are you sure about the blood test results? Those show that he is producing too much thyroxine (as thyroxine goes up, TSH goes down). He can take meds to block his thyroid producing so much, but it wouldnt be taking extra thyroxine.

@SeaToSki

just check another blood test and it says:

TSH 0.09 range is (0.35-4.94)
T4 8.8 range is (10-14.3)

She definitely said Thyroxine

thsnks

It sounds like he might have something like Graves Disease, which is over production of thyroxine, not under production. Definitely clarify with the doctor before giving your son any medicines or treatments

https://www.stanfordchildrens.org/en/topic/default?id=graves-disease-hyperthyroidism-in-children-160-5

No over-production there. Looks like secondary hypothyroidism (low TSH/low FT4). That is a pituitary issue, which may explain the delayed puberty as well,

Yes agree with @DeedIDo. TSH (thyroid stimulating hormone) is a pituitary hormone that should increase as production of thyroxine decreases, to tell the thyroid to make more thyroxine.

In your son's case it looks like this feedback loop isn't working, so although thyroxine is low, the pituitary isn't responding by increasing TSH.

Thank you they have mentioned an MRI of his pituitary gland - this was tested via blood or something similar and was normal but she is wondering if the gland is on small side.

so why is she offsetting thyroxine I'm so confused. She is a private encrinologist (sp)

Hi op, I'd contact the British thyroid foundation as they've done a lot of work for children who need thyroxine. Reference values are different for children iirc.

I agree the results look odd though.

She is giving thyroxine as his circulating levels are too low. He has low levels of Thyroid Stimulating Hormone, rather than high, which is what you normally see when thyroxine levels are low, as the body tries to increase levels. So in his case the feedback isn’t working, he needs his pituitary looked at, but he also does need more thyroxine.

Although you and he think he is asymptomatic, I would not be surprised if he feels a lot better on thyroxine.

As he and you have never known him with thyroxine, he may not know what normal feels like.

@AnnaMagnani that is what I am wondering and hoping as may explain low level concentration etc..

Thanks everyone for your replies so helpful! X

Hopefully his concentration will improve. Symptoms can be rather ADHD like / easily distracted / or executive function.

Hi there - posting again as my son started on thyroxine in Feb and his blood test results are worse than before

TSH 0.01 (range 0.35-4.94)

T4 is now however normal at 10 (10.0-14.3)

he has had scan or purpuity gland and it's normal / no autoimmune condition found

he has had a huge growth spurt since starting these and more energy but the bloods are worse

any ideas?

GP just said repeat in two months

thanks

How does he feel? You say more energy; has thyroxine improved things?

What time of day are bloods being taken?

Is he taking any vitamins? Biotin (b7) can sometimes interfere with the blood test results. It's best to stop taking them for a week or so before a test.

Thanks - he has been having blood tests for another condition and was picked up and flagged buy accident over the passed few years so now they said let's try him on 25g of thyroxine - he has only just started puberty and had a growth spurt it seems after he has started them but now think it must be a coincidence!

he takes a teen multi vitamin

Hi @Remmy123

I have primary Hypothryoidism ie my thyroid failed so I am on Levothyroxine and Liothyronine. It's when the TSH (made by the pituitary) keeps going up and up trying to tell the thyroid to make more T4 but the thyroid fails to make it.

Hence High TSH and Low Free T4 (fT4) and Low Free T3 (fT3)

What your son's issue looks like going on the results you shared, is that the pituitary is not sending out sufficient TSH, so the thyroid doesn't realise it needs to make more T4.

Hence Low TSH and Low fT4 and Low fT3.

Symptoms of low thyroid are awful, but not always recognisable because they start slowly and increase, and don't include anything sudden or dramatic like pain. Feeling cold, tired, lack of energy and concentration, not thinking clearly; I also felt heart palpitations and sort of adrenaline attacks in my chest, had puffy skin, thinning hair, flakey skin like a blizzard on my lower legs, dry lips, the list goes on. Replacement thyroid at the right level got rid of all these things for me.

His most recent bloods don't look worse to me! His pituitary is failing to produce sufficient TSH, so whether that is 0.12 or 0.01 is not a reliable thing to go by. Both are too low anyway. His fT4 has improved; however it is still too low

Doctors I have had always say the fT4 needs to be at least mid range for a patient on thyroid replacement. Then the fT3 also needs to be in range (NHS is often too stingy to test this unless requested by an endocrinologist).

So, as a non-medical professional but long-term thyroid patient under consultant care, it looks to me like:

1. Your son needs to be under consultant endocrinology care
2. He needs an increased dose of Levothyroxine to bring his fT4 up to mid range. In the range you gave that'd be at least about 12.00
3. His fT3 should be tested. This also needs to be mid range.

Good luck.

@SummerCycling thank you so much for explaining this so me in such a clear way that I can understand it better.

i think his ft3 was tested I think I need to take a look back or ask his encrinologist - glad you do not think the results look worse.

in the past he did have times when he said his hand was shaking and also heart palpitations so this must have been why although hasn't had that for a very long time

I wonder if thinks can kick start themselves because he is already on life long meds for another condition 🥲

thanks again

To me these look like underactive thyroid results in terms of T4 and overactive in terms of TSH. When I'm overactive my TSH goes down (under 0.3) and T4 higher (over 25). Underactive means the TSH goes up (over 4) and T4 down (mines never been lower than 12). These seem strange for sure. Did the endo explain why the results are unusual? My endo has always said T4 is the most important measure because the TSH lags behind, and likes patients to be in the upper third ref range.

ETA just seen your ref range for T4, perhaps it's different from mine which ranges from 10-24. 14 is still very low to me.

Agree that this looks like a pituitary problem, not a thyroid problem. His T4 is low, which is hypothyroidism. But if it was primary hypothyroidism his TSH would be high, trying to force his thyroid gland to work harder. So sounds like it's pituitary hypothyroidism, where the pituitary gland is unable to produce enough TSH, so nothing to drive the thyroid into working. Agree that this needs endocrinology advice, not just GP, as much rarer. Hope he's had his other pituitary hormones checked. Glad to hear he's had an MRI.

Thanks everyone - yes the encrinologist has done loads of hormone / perpuity checked via mri etc and all normal/ testosterone as he has delayed puberty and had slow growth/ checked his thyroid for any tumours etc

after his previous results and his gp calling me in a panic she said let's try him on a small dose of thyroxine and that was that (blood tests are done via gp)

I emailed her his latest results yesterday to see what she thinks - I do struggle with his meds and it often ends up being taken 20 mins before breakfast I wonder if that's why results arnt level yet

thanks