What else can it be? :(

My son (who is 18) was diagnosed with an underactive thyroid yesterday. His TSH was 7.71, he was prescribed Thyroxine 50mg. However I am not convinced, he is very UNDER WEIGHT BMI is very low and confirms underweight. This was the reason I took him to the Drs. If anything I thought he may have had an overactive thyroid. He eats absolutely loads and although he is at Uni, eats exceptionally healthy. I spoke to my regular GP today and voiced my concerns, he agreed with me that something isn't quite right and being so slim just does not match his TSH, he wants to do more tests and has said do not give Thyroxine yet. I am so worried, any ideas or opinions please?

20 Replies

Actually, quite a few people with hypothyroidism are under weight at diagnosis, so I wouldn't rule it out just yet. Not sure why this should be, but hypothyroid folk are often hyperactive - I know, sounds like a contradiction in terms.

I'm sure other folk will come along with their experiences shortly.

Thank you x

I was very thin as a teenager and had classic hashimotos symptoms, but wasn't diagnosed until later in life.Perhaps there is an adrenal problem as well.

Thank You, going to mention Adrenal gland to Dr x

My sister in law was severely hypo but very underweight. I believe ive read that about 8% of hypothyroid people present with weight loss but im not sure where i read it now.

Thank you, puts my mind at ease a little x

Clare, Weight gain is a typical hypothyroid symptom but there are exceptions. After a lifetime of being underweight with a low BMI I gained 13kg over a couple of years and then lost it within 10 months prior to a diagnosis of Hashimoto's. I had a thyroidectomy in 2012 and have lost more weight subsequently.

Thank you, it's all so worrying :(

Hi Clare, do you have any other results you can share with us? t4,T3 and antibodies. I went to the docs when I had a lump in my throat and I had been losing weight despite already being a healthy weight. I was thought to be overactive but it turns out it was just my thyroid having a final fling before it went under active. Maybe that is something similar to what is going on with your son. If you can post the extra results Then there are some really knowledgable people on here who can advise you. if only TSH was checked then you should insist on the other tests also so that you can have the full picture. X

Thank you so much, have FREE T4 which is 13.3. His Lymphocyte Count was flagged as low @ 1.3 25.8% Serum Folate was also flagged as high @ 8.6 x

His TSH certainly indicates hypothyroid

have thyroid antibodies been done ?

Not that I know of, spoke to our reg GP earlier and more tests have got to be done now, tomorrow, I queried anti-bodies. He goes back to Uni Saturday so need to get bloods done tomorrow so hopefully get some clearer definite answers :(

A number of things go round my head here.

First, is his thinness/low weight due to loss of muscle or lack of fat? Many hypothyroid people lose muscle mass (sometimes even as they put on fat and water weight). So low weight/loss of weight on its own is not a clear guide.

Second, what was his Free T4 (and, ideally, Free T3)? If you say you don't know, find out. This could be the key. Some people produce too much TSH. That makes the thyroid hormone levels rise, resulting in symptoms of hyperthyroidism. However, if it is only a marginal excess of TSH, the symptoms may not be as severe as often occur in Graves. In my view, you absolutely MUST see if the TSH and FT4 are discordant with each other.

This is a very important reason not to rely on TSH alone. It misses situations where the hypothalamus and/or pituitary are causing the thyroid hormone problem.


Hi Rod, his TSH is 7.71 and his FREE T4 is 13.3 is also has a low lymphocyte count @1.3 25.8% and high Serum Folate @ 8.6. He has always been of slight build but eats healthy and lots of it! Free T3 wasn't tested. More bloods being taken tomorrow after I voiced my concerns to our reg GP today. Going to adrenal too after someone on here mentioned it. Thanks, Clare

My daughter was rapidly losing weight until she started thyroid treatment! She's been fine now for almost 20 years.

Was she diagnosed as hypo (under) or hyper (over) though. With hyper it is normal to lose weight however my son is hypo so would normally carry excess weight.

Very, very underactive.

Oh right that makes me feel a little better, Thank You

I hope your son starts to feel better soon. My daughter really improved on Thyroxine, but it wasn't until she was changed to natural desiccated thyroid that everything was 100% again.

I was diagnosed purely on the TSH. Mine at the time of diagnosis 5 and a half years ago was 5.3. I had no T4, T3 or antibodies test done. The only antibodies test I ever had was 2 weeks ago and mine are high - have a look at my previous posts for readings, despite being on 200 thyroxine and 25 liothyronine, doc reduced me to 150 thyroxine and 20 liothyronine so am currently on that dose. I always insist on TSH, T4 and T3. I am on a T3 medication - liothyronine. I don't always get what I want, as my gp only monitor on the TSH, though last bloods I eventually got all bloods done, though I had to fight for it.

I suspect that I was hypo for years prior to diagnosis. From my early teens I had anorexia up til mid/late 20s so if I was hypo then, they wouldn't have noticed due to my weight. Currently a normal weight, though would rather be a stone less as I am not at my comfortable weight. Would like to be a size 8 again, not a sixe 0. Am a 10 at mo. Though, they also were not diagnosing people until the TSH was more than 10 - so in effect, I would not have got diagnosed. Have had symptoms most of my life. Most people in my family are hypo.

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