Hi all, following on from one of my previous posts with recent bloods showing that I'm pretty badly hypo, it would seem that my endocrinologist has finally caught wind of these results as he gave me a phone call earlier.
He seems to finally be willing to explore the malabsorption possibility, and said that he has organised a day for me to spend at the hospital to monitor my absorption of both levo and T3, in addition to a consultation in a few weeks. He said that the test will entail me going into the hospital, taking both levo and T3, and then having bloods taken at regular intervals to see how well the medication is absorbed. Has anyone else had this done/know what to expect?
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lau99
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Never had it done , but have read about it in lots of endocrinology material telling them what to do to get to the bottom of unexpected/ confusing Thyroid Function Tests.
it is basically just a compliance test... before they move on to investigate other more interesting causes for your weirdly high recent TSH result ,
They need to confirm that you are actually taking the tablets you say you are. So they watch you closely to make sure you actually do take them, then they test your blood at intervals afterwards to see what happens.
Try not to get too annoyed ... they know it can seem very insulting (and so they wont actually tell you you are being 'observed' to check you do take the tablet) .... but it is a necessary step in the process of proper investigations into weird results . They have to rule out the possibility that you are just not taking them... it's not personal.. it's just the first part of a process of elimination till they find the answer to the puzzle.
It will be useful .. they will get some detailed results , and will hopefully stop blaming 'non-compliance' for everything .. and move on to do some proper investigations ... if poor absorption is proven they will be happier to prescribe unusually large doses....... and you will find out how much you absorb and how quickly.
They will probably end up with some graphs a bit like these ones , showing blood levels for TSH , fT4 ,and fT3 at regular intervals for (in this case )24 hours after taking the dose under controlled conditions. These images are a bit blurry but they are comparing what happens to;
a) fT3 .
b) fT4
c)TSH
when someone takes just Levo , compared with what happens when someone takes Levo + 10mcg T3.
Thank you so much for such a detailed response, tattybogle. I do wonder though - since we tend to forego the most recent dose of T4 before a normal blood test, will they see the high levels like they're expecting (since they're monitoring the medication as it goes through my system) and use that as proof of non-compliance? Or is it more of a measure to see if, say, my levels are lower than they would expect to see from a particular dose? (I hope that makes any sense 😅)
Also, what might they do/suggest if the test does show that my absorption is impaired?
i don't know , i've never come across any detailed information on 'how to interpret the results' lying around on the internet, for obvious reasons they don't tend to publicise it. ......i've only seen it discussed in relation to to checking T4/Levo , because obviously teaching material doesn't expect them to be dealing with many patients taking T3.
and in all honesty , it probably isn't helpful to try second guessing what they might see, or think , and what they might do about it .
Because we don't know what's in their head, or what they are looking for, or even if they do think you are non-compliant, or whether they already believe you ARE compliant and are genuinely looking for more detailed answers about your absorption.
IF the test is just used to check compliance with Levo taking, eg in the case of a patient who has inexplicably high TSH despite insisting they do take the tablets regularly, (but they have reason to think perhaps they don't take it regularly) then it is really just suggested to check if when they take a levo tablet , does it show up as increase T4, and does that have the expected effect on lowering TSH .. i don't know any detail on how they decide 'how much of an effect' proves what they are looking for.
When i've seen this 'observed absorption test' mentioned in training documents , it comes with carefully phrased instructions on how to do it without patient realising that the 'observation' part is to make absolutely certain the patient DOES swallow the tablet and doesn't have the opportunity to go to the bathroom and spit it out straight afterwards, or hide it in their handbag.
Things like "get the patient to go to the loo before the test , so they don't have a need for the bathroom straight after the tablet"
But we don't know this is what they think on your case , they might be genuinely interested already .. so don't go in feeling suspicious , just do it with an open mind and see what further information it leads to.
(just don't be too surprised if nice nurse seems to want to follow you to the loo )
I assume .. (and it is just an assumption) that if they are satisfied that when you eat Levo and /or T3, it doesn't have the expected effect on T4 /T3 or TSH levels , then they will look further for 'why not '... and will not always have to think "? could it just be poor compliance? " in future when they get weird results.
perhaps they will then send future 'weird' blood results to another hospital that can rule out test interference due to something in your blood interfering with lab process , meaning the high TSH isn't always a reliable result in your case.
Perhaps they will allow prescription of unusually high doses to overcome the poor absorption.
But whatever happens, i'm sure it will be interesting and ultimately provide useful information ... Be hopeful .. at least they are properly looking at you now .
DON'T go in and say you've been researching this test ... they may assume you have been trying to cheat... go in like the honest, ill , un-suspicious person that you are. and let them see what they find.
Don't worry about 'what if' just now .... you can cross that bridge if you come to it.
hi Ceri .. I'm sorry but there are lots of inaccuracies in your reply ,
"So you take the synthetic hormone as T3 and it converts to T4." .....No, that's not possible ..... it's the other way round. T4 is converted into T3 .
"This I would think shows how well the exchange is working.. in the parathyroid". ... It is NOT the parathyroid that converts T4 to T3.
"Usually things go wrong if your thyroid or your parathyroid underneath your thyroid is not working". .... the parathyroid glands have nothing at all to do with thyroid hormones , they are involved in calcium regulation. They are only called PARAthyroid glands because they happen to be right next to the thyroid gland.
"I take my tablets Synthyroid under the tongue by dissolving them and absorption is better as they go straight into my blood stream." ......That not possible either, you can dissolve them in your mouth if you like , but apparently the molecules are too large to go through your gums ... so the Levothyroxine can only be absorbed into the blood stream when the saliva they are dissolved in, reaches your gut.
" I understand that TSH is the conversion" ...No, TSH is a signal from the pituitary gland to the thyroid gland to ask for more or less thyroid hormone to be produced. It can't really tell you anything about how well you convert T4 to T3
"Thyroxin dose is calculated on your weigh like 1.6 x kgs." .. This is only a very rough initial estimate of what dose someone might need... in reality many peoples dose ends up being very different to this estimate .
I am afraid that some bits of your response could be very misleading.
I'm not sure that I even understand "TSH is the conversion"! TSH is the hormone released by the pituitary gland, which tells the thyroid to make and release thyroid hormone.
Once anyone is taking levothyroxine, using the 1.6 micrograms per kilo dose calculation is almost entirely useless. That makes sense in some circumstances when starting levothyroxine, but is not suitable for assessing the dose once taking levothyroxine.
You say "T3 converts to T4" and that is just wrong. T4 gets converted to T3. It never goes the other way - or at least, no medical or scientific person even suggests that it might happen.
Hi. You hav a miniature schnauzer as well. Top dog. I breed them in UK and NZ. I take my Synthyroid under tongue as absorption is better and I dont hav a gall bladder.
When taking thyroxin via mouth and swallowing it is important to take with water on empty stomach.
When I take mine I have a little banana 1/2 hr later.
I too hav a rapid persistent irregular heart beat.
History Stroke in 2019 found to have above and 3 days later during neck scan of carotid arteries found to hav papillary thyroid cancer which had spread into 2 lymph nodes as well. 12 were removed with thyroid total.
Thyroidectomy Feb 2020 4 months later.
2 years with no returning or left cancer cells I keep TSH between 2.0 and 3.0. Never went down into supression. Lowest in the latter part of fist year was .9...
I take 125mcg Synthyroid.
Sometimes I take 150mcg to stay in the above zone.
I had trouble with metroprolol this horrid drug made me breathless.
Changed by cardiologist 1 year 6 months later to Bisoprolol.
But went to a private heart specialist who changed me to Diltiazem 120mg a.m and 2.5mg at night.
Heart rate dropped.... Highest at rest 93. And ECG shows 93 as well. Finally controlled.
They say that a Thyroid problem can cause AF and you dont want that.
I reduced my PRADAXA to 110mg twice daily and my energy is returning and my natural teeth are no longer weak, Couldnt eat my usual grain Arnotts crisp crackers. Also rash has gone down.
PRADAXA is a blood thinner which is reversible.
Synthyroid thyroxin is more stable and I changed for that reason. Also easiier to tip into han, has an expiry date and a kiddy lock. Others are bought in bulk.
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Prescription from private endo
Update on Endo appointment today
Just back from seeing the Endo. 
My endo appointment today, confused to say the least.
