Thyroid UK

How to adjust T4/T3 medication, correlation with tests, symptoms and priority

Dear Group,

I won't start otherwise than with a big thank you, you are, at least for me, THE source for real life experience in approaching the thyroid hormone replacement therapy (after TT in my case)

I am asking for your experience in dosing the meds considering tests and symptoms. as a short overview, after TT in 2013 and two years on T4 (initially well but in the end plagued with hypo symptoms, mainly related to cognitive function) had switched to combo T4/T3 meds that I have adjusted a few times.

Now, while now I am stable with the medication, 125 T4 25 T3 split in two daily doses, results of the tests are fluctuating (morning drew blood, before dosage, 10-12 hours after previous dosage);

While on the same dosage and, though not impeccable, rather decent absorption conditions (20 min minimum from meds to coffee:)

TSH dropped from 1.5 to 0.38 and then rise a bit to 0.46 (interval 0.27 - 4.2)

FT4 fluctuates significantly from 16 to 19 and then 14 (interval 12-22) To be mentioned that personally the FT4 under range is affecting me significantly on energy levels, I've experienced that already

Same trend in FT3...6.2 - 8.7 - 5.8 (interval 3.1 to 6.8)

TT3 is more stable...2.2 - 2.7 - 2.1 (interval 1.3 to 3.1)

Symptom wise I'm quite constant and functional, apart some joints discomfort that I can't put the finger on...the bad old days of terrible brain fog, inability to think clearly, depression and energy fatigue seem over, thank me! :)


1. How do you adjust your meds to target test results and symptoms?

Clearly, between symptom and various tests results, there is a balanced priority to addressing the symptoms.

2. Do you see such variation on test results when everything else constant? Do you do something about it or simply monitor it with symptoms status in mind?

3. this one is complicated - How do you know when your dosage has reached the maximum potential of relieving symptom? After messing up with everything for such a long time I am somehow unsure where the "normal" is...

Thank you for your time and willingness to share your experiences, I need again real life advice and guidelines.

5 Replies

Did your Endocrinologist advise you to divide dose? It's unusual to split T4/T3 combination.

Blood tests can vary throughout the 24 hours of the day. TSH especially, which is highest a.m. and drops throughout 24 hours.

Before blood tests were introduced we were diagnosed upon symptoms alone and given thyroid hormones untiil all symptoms are relieved. If symptom return small increases in hormones was given.

Maybe this link will be helpful:-


Thanks Shaw, yes, one of my Endo's (I've seen around 5 until now but this is the only one that recognized a potential issue of T4 only treatment due to DIO2 polymorphism - he's a leading endo professor and handles research also) recommended to split doses at 12 hours time (I think correlation with circadian cortisol production is his main reason)

the other endo I see for second opinion and ordering tests expressed also concern that dosage splits are unusual and against common practice; but I'm quite good, perfect sleep, no issues (40% dose at night, 60% dose in the morning)

Will take a look on the link, thank you!


What I have read is that if taking T3 and as it doesn't need to be converted, that it's job is to saturate the T3 receptor cells and then it's work continues between one to three days.

Levothyroxine has a long-lasting half life.

I thought that if someone had the DIO2 gene defect they could only take T3 as the gene prevents conversion of T4. Someone will correct me if I'm wrong about taking T4 when you have a defective gene).


I am unsure if confirmation of DIO2 defect would render T4 completely ineffective. I plan to make the DIO2 test but money is scarce these days :)

if I take a single dose I might get a little hyper rush on the same dosage; the split works good I believe. Even when on T4 only I have noticed better sleep when dosed at night...but this is me...


On levothyroxine alone I got much worse with more clinical symptoms that when my TSH was 100. However, I did go through the route of T4: T4/T3: NDT and now T3. This was over several years. Now I feel well on T3 only with no clinical symptoms so assume I probably have a defective gene as I believe that it was T4 in all of the products which affected me. I haven't had a gene blood test but I am happy and well now.

Another link which might be helpful and go to the date August 13, 2002

n deciding what dose of thyroid hormone is safe and effective for a patient, urine levels of T3 and T4 are as useless as blood levels of the TSH, T3, and T4. (Elsewhere, I've give my view on the use of free T3 and free T4 serum levels to adjusting thyroid hormone dosage.) The response to a particular dose of thyroid hormone varies in different tissues in the same patient, and the response varies in the same tissues in different patients. The typical patient wants more than most anything else to overcome her symptoms and recover her health. To achieve this, variable tissue responsiveness dictates that she use a thyroid hormone dose that produces desirable tissue responses—regardless of what the dose does to her blood or urine T3 and T4 levels.

This doctor was also a scientist and a critical analyst. Excerpt:

Dr. Lowe: As a rule, our patients take thyroid hormone only once per day. An advantage of this one-per-day schedule is that it’s easier to find a window for good intestinal absorption—when the stomach or small intestine doesn’t contain food.

Most of our patients wait at least one hour after taking thyroid hormone before they eat. Or they wait at least two hours after eating before they take thyroid hormone. The two hour wait is a rough estimate of the time it takes for food to pass through the stomach and small intestine. It’s worth noting, however, that several factors can increase the time a patient should wait before taking thyroid hormone.

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