T3 T4 combination, what to do next ?! - Thyroid UK

Thyroid UK

121,047 members141,048 posts

T3 T4 combination, what to do next ?!

Maron007 profile image

I started on 10micrograms of T3 Sep17. After many years of asking because I have never felt well on t4 since I started taking it. I am currently taking 100mcg of T4 with 20mcg of T3. On my last visit to my Endo she was concerned as my TSH is 0.03 and said that it was not making any difference to my t3 levels and that I need to drop t3 dosage to 10mcg to increase my tsh.

Having done this back in August within 8 wks my hair started to fall out and I felt exhausted with terribly fatigue. So I increased t3 again to 20 mcg.

I would like to know if when I started taking t3 if my t4 should have been reduced ? My dosage has stayed the same 100mcg though since starting t3 the t4 level has dropped considerably and my t3 highest level is 4.8 . ( Jan17)

Most recent blood results

TSH 0.03 0.35-5.00mu/L

T4 14 9.00-24.00pmol/L

T3 4.4. 3.50-6.50pmol/L

I had loading B12 injections in June and have just recently had my 2nd 3 month injection both times I have experienced 10 days prior to injection, cramps in my left arm with pins and needles and numbess. My dr has now agreed to my b12 injection every 8 weeks.

I have my Endo appointment on the 31st and have a feeling she will withdraw my t3 based on my TSH. Should I be asking to reduce t4 to 75/50mcg and add more t3 ? Hoping that this will optimise dosage and help with symptoms. Or NDT perhaps ?

Thank you all in advance for your thoughts

Related Tags


Reply Like (0)


3 Replies
SeasideSusie profile image


So we can fully understand your T3 journey, can you list the results please (include the reference ranges as they differ from lab to lab).

If we can see your results before you started adding T3 that will tell us if you needed to reduce your dose of Levo.

Then list results for any dose changes so we can see what's been happening.

An endo who prescribes T3 should know that taking T3 will lower, even suppress TSH, and can also lower FT4. If they don't know that they shouldn't be seeing thyroid patients and prescribing T3.

Your current results don't show a need to reduce your dose of Levo, it does show that you need more T3.

Are you taking your Levo and T3 correctly so that nothing interferes with their absorption - i.e. on an empty stomach, one hour before or two hours after food, with a glass of water only and water only for one hour either side? Are you taking your thyroid meds at least 2 hours away from any other medication and supplements?

As you have a B12 problem, have your other nutrient levels been tested:

Vit D



Have you had thyroid antibodies checked and were they raised confirming autoimmune thyroid disease aka Hashimoto's?


Sudden changes in T3 dosing can influence hair growth just as much as too much or too little.

You should not be asking to reduce Levothyroxine and increase T3 meds as your FT4 levels are still not optimum and this could be your answer in achieving well-being.

20mcg T3 is a good dose when combined with Levothyroxine but you sound under medicated in T4 and your level allows for an increase as is under halfway through range. This would help raise T4 levels, and the 20mcg T3 already medicated would aid in further conversion of T3 from this additional medicated T4.

Low TSH levels are common when medicating thyroid hormone replacement containing T3 as the pituitary senses enough T3 hormone and reduces secretion of Thyroid Stimulating Hormone (TSH). Your endo should know this but many are many ignorant on the workings of thyroid hormone physiology.

A Vit B12 deficiency indicates a gut absorption issue. Have you had Vit D, folate and ferritin levels tested ? ? ... Optimal levels are not only vital for good thyroid hormone synthesis and low ferritin is also linked to hair falling out.

SlowDragon profile image

Most importantly how do you do your blood tests?

All thyroid blood tests should ideally be done as early as possible in morning and fasting. Do not take Levothyroxine dose in the 24 hours prior to test, delay and take immediately after blood draw. This gives highest TSH, lowest FT4 and most consistent results. (Patient to patient tip, best not mentioned to GP or phlebotomist)

If also on T3, make sure to take last dose EXACTLY 12 hours prior to test. (Or between 8-12 hours maximum)

Is this how you did the last test?

Are you taking T3 as split dose?

Some of us need to take as split dose - 3 doses per day (8 hours between doses) typically on 20mcg - that's 10mcg at 7am, 5mcg at 3pm and 5mcg at 11pm

Others manage 2 doses a day - 12 hours apart

Others can take as single dose.

Essential to have good levels of vitamin D, folate and ferritin as well as vitamin B12

Do you have Hashimoto's? If so, are you on strictly gluten free diet?

TSH is virtually ALWAYS suppressed on T3 , if your Endo is surprised at this she's not experienced in T3 treatment

You may also like...