Both my doctor and I are puzzled, and I'm wondering if you can help shed any light on what may be going on? Apologies for the length of the following, I am trying to be as thorough as possible.
For at least 10-12 years, my TSH has been gradually climbing and last month was 8.97 mU/L (Australian reference range 0.40-4.00). My free T4 and free T3 are normal and stable over time. I had a thyroid ultrasound twice, 5 years apart and, while there were a few nodules, there was nothing major to find, and there was no change at all in its appearance in 5 years, despite my TSH going up over that time. I've had elevated ANA (nucleolar pattern) for 20 years, although in the past 3 years the level has begun to fall. All my ENAs are negative, and CRP is negative.
I sleep well and eat healthy, have a happy marriage and a stimulating and rewarding job, yet I'm tired a lot, have muscle and joint aches and pains, but no arthritis. I've been getting mild Raynaud's in my fingers for about 20 years, but this has improved slightly in recent years. Apart from the Raynaud's, I don't have intolerance to cold (a classic hypOthyroid symptom), but do have a bit of trouble tolerating hot weather (a classic hypERthyroid symptom).
Much of the above would suggest autoimmune hypothyroidism (Hashimoto's), however I test negative for Thyroglobulin Antibodies and Peroxidase Antibodies. In addition, my haematology, blood chemistry, blood sugar, iron studies and total cholesterol are normal (although with a slightly elevated LDL, which I'm working on lowering via diet). Vitamin D was low 12 months ago, but is normal now (after taking D3 tablets). I'm negative for both Lyme disease and Coeliac disease (antibodies and genetic testing). Several years ago I tested positive for IgG antibodies to wheat, milk and egg proteins and I have all but eliminated these from my diet. I add no sugar or honey to food or drink and eat mainly fresh meat, fish, vegetables, fruit, nuts, and gluten free grains. I don't smoke and rarely drink.
Two or three years ago, the doctor tried me on a low dose of thyroxin (I forget what the dose was, but I took 1/2 the smallest tablet available). If I had Hashimoto's we'd expect me to feel better and the TSH levels to fall. After a couple of days I did feel a tiny bit more energy but from the 3rd day I felt much worse, as I couldn't sleep for 48 hours and I had tachycardia and palpitations the whole time. I tried taking the 1/2 dose every other day, but I still had difficulty sleeping and my heart continued to race. So that little experiment was terminated poste haste!
My GP today suggested a pituitary MRI, I guess to check for adenoma, as this might explain an excessive production of the TSH. But this is expensive, so before going that road, she's ordered some more pathology tests: prolactin, ACTH, morning cortisol, PTH (parathyroid hormone), urinary specific gravity, and magnesium. I guess if any of these come back abnormal, we'll have a better sense of what to do next. But if they're all normal, we're both going to be a bit stumped! I am menopausal, but my hormones, including FSH, are normal for this stage of life too.
What are your thoughts so far and what else do you think we should be looking at? Could there be resistance to TSH, if so why? Or something going on in the hypothalamus, e.g., too much TRH causing overstimulation of TSH? Why I'm wondering about the hypothalamus is because I am a carrier of the most common mutation for Cystic Fibrosis, the delta-F508 gene, and I know from my reading that recent studies have found problems in the hypothalamus in CF patients. I know carriers are supposed to be asymptomatic, but knowledge about this and other conditions is constantly being updated as further studies are carried out and discoveries made.
There are other members that are more knowledgable than I here on the forum, but I have been told and read that other conditions exist that cause fluctuations and changes in thyroid hormone levels and TSH, nut are not caused by thyroid itself, I recall low Ferritin and Iron levels, also one test that you mentioned your MD is going to test for is Cortisol and Adrenal Fatigue or insuficiency. Because the TSH is controlled and secreted by the Pituitary and not the thyroid, and if your thyroid hormone levels are, and have remained the same, as your TSH has risen, then it would be something giving the Pituitary the wrong signal that thyroid hormone is low, or the Pituitary itself. Has your MD done thyroid hormone tests Free T3 and Free T4 ? If he has, could you post the levels and ranges provided with each, these are much more indicative of what the thyroid is producing than any other tests, and it would be these hormone levels that the Pituitary senses and bases TSH on. Thank You FTB4
I have pituitary resistance to thyroid hormone (PRTH). The pituitary converts T4 to T3 for itself. My pituitary lacks the enzyme (5'deiodinase) that catalyzes the conversion of T4 to T3. So, my pituitary is starved for T3 and "thinks" the rest of my body is, too. It's not, I convert peripherally just fine. Pituitary adenoma is only one possibility. My TSH hovers around 20.0 all the time regardless what My FT3 and FT4 are doing.
Would you post recent FT3 and FT4 levels? Please include reference ranges as they vary lab to lab and country to country, so they have to come from your own lab report.
I am asymptomatic (on meds because I do have Hashi's), but you sound symptomatic.
hi FTB4, thanks for such a quick and comprehensive reply! Apologies for my brief answers below, as I'm about to go out and am working to deadlines today.
- My Ferritin and Iron are fine - always in the normal range.
- Yes, my MD is investigating why my pituitary might be secreting too much TSH.
- Every time TSH is tested we also test free T4, which, over the past 10 years, has been consistently between 12 and 13 pmol/L (Australian reference range 9.0-19.0). Often when she requests free T3 the lab doesn't do it, but when they do, it is normal. The most recent reading was in December, 4.5 pmol/L (ref range 2.6-6.0). i.e., FT3 and FT4 are very normal and virtually unchanging, while TSH is slowly increasing over time.
Your FT3 and FT4 look good for someone not on meds. If you don't have hypo symptoms, you should be pretty happy with those.
My PRTH is a "working clinical theory". It's based on the fact that I have gone hyper (on meds since I also have Hashi's) with a TSH of 20.0. My TSH hovers around 20.0 no matter where my FT3 and FT4 are. In fact, sometimes when FT3 and FT4 go up, so does my TSH, sometimes they all go down together and sometimes they behave.
There is a genetic test for thyroid hormone resistance (it's a genetic mutation), but I have not explored it at all since I have very high deductible insurance and would be paying for it out of pocket. I would explore it, obviously, if I didn't feel well, but I do, and ignoring my TSH works just fine for me.
Just to confuse matters...there is more than one kind of thyroid hormone resistance. Some authors say there are two, some three. There's pituitary resistance, which only affects the pituitary, and there's peripheral, which only affects the body, not the pit, and there's general (both). In addition, many people refer to RT3 dominance (an entirely different condition) as thyroid hormone resistance, so you have to be very specific about what you call it and make sure the person on the receiving end is on the same page.
I'll have to ask my endo next time I see him if the genetic test picks up pituitary resistance.
Thanks again goolara. I think I'm having brain-freeze (not your fault) from all this info, but will gradually digest it. There's probably not much more I can do until I've had the next round of tests. Meanwhile I'm getting stricter about staying off gluten and dairy, and keeping on taking the fish oil and vitamin D as precautions.
Let me know how you go as well, or if you find out anything more about your PRTH. When you think about how complex our physiology and biochemistry are, and how many things can potentially go wrong, it's amazing how we all manage to get around OK every day, don't you think?
It is amazing we all remain functioning. I think the body has an incredible capacity for compensation...redundant systems that can take over for each other (and we don't even know it).
I will let you know. I was diagnosed with PRTH several years ago now, and I did a lot of research at the time. It's not easy stuff to get through for the most part. Also, pituitatry resistance is often pretty much ignored. The big draw with THR is the genetic component, and you can imagine the brain freeze reading about that gives you! Anyway, it may be time for me to see if there's anything new out there on PRTH...it's on the list.
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