Levothyroxine malabsorption study

[jimh111]

Interesting study on levothyroxine (LT4) malabsorption doi.org/10.1530/EC-22-0355 raises a number of issues.

The authors refer to 'pseudomalabsorption' without defining it although other studies refer to it as non-adherance to the drug. The study concludes that most patients performed normally during the trial - the trial data show this is not true.

The trial included ten patients from a tertiary care centre over a period of six years who were on high LT4 doses and had high to very high TSH and low fT4. It raises the question of why these patients were not sorted out long ago. If a car has a minor emissions failure it is taken off the road and the customer gets it sorted within a week or two - it seems an endocrinologist cannot perform to the same standard as a mechanic.

Although there is a subtle attempt to blame the patients the data suggests only one (patient A) may have been non-compliant. The follow-up evaluation (Table 3) shows that only two patients (A & F) achieved normal TSH, fT4. A 20% success rate, assuming they felt well also. I wouldn't use a garage that only managed to fix one in five cars.

It is claimed none of the patients have malabsorption but they needed on average 2x the normal dose of LT4. Five of the patients were identified as celiac! It is claimed five patients have 'improved hypothyroidism', this is not defined but they had TSH between 12.3 and 40.2 - no mention of symptoms. Patient B had a TSH of 40.2 with fT4 2.07 (0.95-1.57) after 33 months follow-up, no investigation into why TSH is so high with a high fT4.

The manufacturers of LT4 should have done this sort of research 40 to 50 years ago given the volume of sales.

[helvella]

Perhaps we should suggest that endos seem to specialise in pseudo-diagnoses and pseudo-treatment?

[Imaaan in reply to helvella]

Lol

[jimh111 in reply to helvella]

and pseudo-euthyroidism.

[Imaaan]

It's the non adherence that kills me. If anything, chronic illness has made most become a stickler when it comes to taking their meds on time at the right dose, everyday all day. Its a full time job and one step away from being OCD.

[Sparklingsunshine]

When my TSH remained stubbornly high, over 6 something, even though I was on 100mcg Levo at the time, the GP actually asked me if it was taking it. I suppose they have to ask but I was pleased to tell him I took it religiously, with water and nothing else, well away from, tea, coffee and any other medications or supplements. Which soon shut him up.

I hasten to add I learnt all of that from this excellent forum. I wasn't told any of this by my GP, pharmacist or by reading the PIL. I think it should be something that thyroid patients are told. But we're left to find it out ourselves. Or not.

[SlowDragon Administrator]

Research article looking at Malabsorption of levothyroxine

academic.oup.com/edrv/artic...

An interesting case needing levothyroxine injections

ncbi.nlm.nih.gov/pmc/articl...

[jimh111 in reply to SlowDragon]

I’m sure there are lots of similar studies. When they can’t work out what’s going wrong they blame the patient. Of course this can’t be done by other (usually better) scientists such as in physics.

I have a sneaky suspicion that a sluggish gut caused by hypothyroidism leads to impaired LT4 absorption creating a vicious circle of hypothyroidism and poor absorption. If so, compensating with a shot of high dose LT4 will break the circle and hey ho the patient recovers on the prescribed dose. The endocrinologist wrongly concludes the patient has been taught a lesson and now complies with the medication. A further consideration is that the body takes time to heal, time not the endocrinologist has effected a cure.

Studies such as these need to be done properly with a placebo arm. This would show if the claimed compliance before the trial actually happens.

[Strongerme23]

Well that explains a lot. I was on Synthroid for a year, and T4 levels never really reached optimum levels while I got anxiety attacks. Fired my endocrinologist, who could only focus on TSH, and moved to a naturopath doc who put me on NDT, which did the trick.

[TLVR]

I asked my endocrinologist why so little medical research was being done regarding this, but she was characteristically vague and dismissive. So irritating.I have graves disease, and the 3 treatments available for this were invented almost 80 years ago.

The 100 mcg levothyroxine I take on my block and replace therapy seems to have minimal effect. I know I've become hypothyroid. But they won't prescribe T3.

[tattybogle]

Fascinating that TSH can move so fast under certain circumstances ...

eg. within 5/6 hrs after 1000mcg Levo dose

a) 93.1 >>> 48.4

e) 228.0 >>> 209.5

j) 6.69 >>> 3.28

i) 1.83 >>> 0.94

" Moreover, the addition of FT3 levels during LT4AT was essential to help explain the safety and absence of side effects observed during the test."

oh right .... so an fT3 test IS seen as essential after all ,.... but only when they are trying to prove you're lying about taking the Levo ..... how nice of them.

[jimh111 in reply to tattybogle]

All the examples I've seen from patients and studies show that TSH responds rapidly to changes in T3 or T4. (bear in mind that we store around 10 days worth of T4 so if you increase a levo dose from e.g. 100 to 125 mcg it will take several days to make a difference to the 'reservoir' of 1,000 mcg already in the blood).

So, TSH responds rapidly to changes in fT3 or fT4. However, I've noticed if TSH has been supressed for a long time, or has been very high for a long time, it takes months to get back to normal if at all.

[tattybogle in reply to jimh111]

i think TSH sometimes behaves a bit like a sliding barn door that takes a lot of force to start to move it ,and then all of a sudden it slides really easily.

mine barely moved at all when i was originally titrating up from 50mcg to 100 to 150mcg (TSH 2.9/ 2.5/ 2.7 mU/L), even though i was each dose for many months ? weird ... then i added a tiny bit more , maybe 175mcg ... and 'whoosh' off it slid, down to 0.001

But yes .. big changes like adding 1000mcg / totally stopping all Levo (ie. hitting it with a big hammer!) do seem to make it shift quicker. sqaaaaaaaaaaaaaaaaaaa344444.

last bit was my cat walking on the keyboard when i went out to answer the door .... result made me laugh so much i decide to leave it there .. very impressed it managed to put a full stop at the end ...lol.

[jimh111 in reply to tattybogle]

Strange. It can happen if you have a partially functioning thyroid (probably in this case as 50 mcg is not much, would have to see fT3, fT4). Cool cat, maybe train it to write more robust notes when dealing with thyroid doctors.

[tattybogle in reply to jimh111]

i'm considering getting it a twitter account so it can 'have a word' with our friend the cookiemonster .

[jimh111 in reply to tattybogle]

Cats like things that tweet.