• Welcome to Phoenix Rising!

    Created in 2008, Phoenix Rising is the largest and oldest forum dedicated to furthering the understanding of and finding treatments for complex chronic illnesses such as chronic fatigue syndrome (ME/CFS), fibromyalgia (FM), long COVID, postural orthostatic tachycardia syndrome (POTS), mast cell activation syndrome (MCAS), and allied diseases.

    To become a member, simply click the Register button at the top right.

What should be the ratio of T3 / T4 supplementation ?

raghav

Senior Member
Messages
809
Location
India
I am currently taking 150 mcg Thyroxine (T4) under supervision of an Endocrinologist for the past 18 years. I am getting Cytomel T3 tomorrow. So in what ratio should I take T3 and T4 ? 50 mcg : 100 mcg ? or should I start with 25 mcg T3. Endocrinologists in India have no idea or experience giving combination of t3 and t4. So what side effects if any that I should be on the watchout for ? Thanks in advance.
 

BadBadBear

Senior Member
Messages
571
Location
Rocky Mountains
NDT is around 1:4. If you take too much T3, it suppresses T4 so its possibly problematic to use too much T3. As well, doses should be divided.

My NDT has about 9 mcg T3 to 38 T4 per grain, and I divided my dose of 2.5 grains into 3 doses.

Overall, my body still didn't use T4 and I have to be on T3 only.
 

Learner1

Senior Member
Messages
6,305
Location
Pacific Northwest
NDT is different.

I'm on 137mcg T4 and 50mcg T3. I used to feel the same on 75mcg of each.

It's not a one to one conversion. Instead of the extra 25mcg T3 I used to take, it took 2.5 times more T4. Other recommendations are 3x to 5x the amount of T3 to T4, which you'd going from T4 to T3.

Ideally, your rT3 will be normal and your FT3 and FT4 will be midrange and you won't have hyper or hypo symptoms. Your TSH may be suppressed if you take T3, but just go by the other labs and how you feel.
 

BadBadBear

Senior Member
Messages
571
Location
Rocky Mountains
Thanks @BadBadBear and @Learner1 Labs in India dont offer rT3 test. Anyway let me start with 25:125 (t3:t4) and see how it goes.

That will be approx the equivalent of 225 mcg of T4 only. I would expect you will need to drop the amounts quite a bit to hit your current dose of 150 mcg of T4.

I would start at 100 mcg T4, 10 mcg T3 which will be closer to your current T4 dose. But it will take weeks for your T4 levels to normalize on your new dose, which is a reason to go up slowly on your T3 dose and let your body adjust.
 

CFS_for_19_years

Hoarder of biscuits
Messages
2,396
Location
USA
I am currently taking 150 mcg Thyroxine (T4) under supervision of an Endocrinologist for the past 18 years. I am getting Cytomel T3 tomorrow. So in what ratio should I take T3 and T4 ? 50 mcg : 100 mcg ? or should I start with 25 mcg T3. Endocrinologists in India have no idea or experience giving combination of t3 and t4. So what side effects if any that I should be on the watchout for ? Thanks in advance.
Cytomel (T3) is about 4 times as effective as thyroxine (T4). If you want to introduce Cytomel slowly, you could start with the first combination:
5mcg Cytomel + 130mcg thyroxine
10mcg Cytomel + 110mcg thyroxine
From here on you might think about taking half of your total Cytomel dose twice a day.
15mcg Cytomel + 90mcg thyroxine
20mcg Cytomel + 70mcg thyroxine
25mcg Cytomel + 50mcg thryoxine

See http://www.allocca.com/papers/Calculating_Thyroid_Replacement_Hormones.pdf

I think the proper ratio for taking T3 and T4 is an individual thing. Most of my thyroid replacement comes from Cytomel because I can't convert T4 to T3.
 

Ema

Senior Member
Messages
4,729
Location
Midwest USA
I take 75 mcg Tirosint (T4) and 5 mcg of Cytomel (T3) in the morning and 25 mcg Tirosing and maybe another 5 mcg of Cytomel in the mid afternoon.

ETA: Whoops, forgot a dose!
 

Learner1

Senior Member
Messages
6,305
Location
Pacific Northwest
Cytomel (T3) is about 4 times as effective as thyroxine (T4). If you want to introduce Cytomel slowly, you could start with the first combination:

5mcg Cytomel + 130mcg thyroxine

10mcg Cytomel + 110mcg thyroxine

From here on you might think about taking half of your total Cytomel dose twice a day.

15mcg Cytomel + 90mcg thyroxine

20mcg Cytomel + 70mcg thyroxine

25mcg Cytomel + 50mcg thryoxine

It's individual. That ratio doesn't work for me.
 

ebethc

Senior Member
Messages
1,901
What's the typical dosage of T3, if there is one? asking b/c I've never heard that ratios are that important...
 

Hip

Senior Member
Messages
17,807
I am currently taking 150 mcg Thyroxine (T4) under supervision of an Endocrinologist for the past 18 years. I am getting Cytomel T3 tomorrow. So in what ratio should I take T3 and T4 ?

The normal average T4 to T3 conversion rate is 35.7%, or around one third. Ref: here.

So if you are taking 150 mcg of T4, then you might expect that to convert to 50 mcg of T3 in normal healthy people.


And if you are taking an extra say 10 mcg of T3, then you might consider subtracting 3 x 10 = 30 mcg from your T4 dose in order to compensate.


Bear in mind that the half-life of T3 is around a day or so, which means that you may want to take your daily T3 dose in two divided amounts, to ensure you have reasonably uniform blood levels. The half-life of T4 is longer, around 5 to 7 days, which is why for T4 once daily dosing is fine.
 

BadBadBear

Senior Member
Messages
571
Location
Rocky Mountains
Bear in mind that the half-life of T3 is around a day or so, which means that you may want to take your daily T3 dose in two divided amounts, to ensure you have reasonably uniform blood levels. The half-life of T4 is longer, around 5 to 7 days, which is why for T4 once daily dosing is fine.

I think the half life does not predict the bioavailability. I need my T3 in 4 doses per day. If I take fewer doses, I have symptoms of too much T3 per dose, and I run out of T3 over night and wake with high adrenaline.

I have heard of other people who can take a single dose in the AM or at bedtime and be just fine.

Seems to vary quite a bit.
 

raghav

Senior Member
Messages
809
Location
India
Thanks folks for the suggestions. I am also taking Testosterone gel 25 mg topical every morning. My endo wants me to go to the full dose of 50 mg of testosterone gel since my testo leveles are below that of the minimum of a 90 year old male. So this will also have to be factored in. Any way I will be testing thyroid and testosterone levels after a month or so.
 

pattismith

Senior Member
Messages
3,926
@raghav , do you take TH to treat hypothyroidism?

T3 should be taken three times a day, this is what showed up in this study by Pr Jonklaas (2016) (below)

Her results (table A) match pretty well with what I noticed when taking T3 with non genomic effect starting an hour later and ended 9 hours after intake.


Daily Administration of Short-Acting Liothyronine Is Associated with Significant Triiodothyronine Excursions and Fails to Alter Thyroid-Responsive Parameters

tileshop.fcgi



in this study where they used T3 or T4 with three intakes per day, they found:

"The dose of l-T3 was 0.57 ± 0.08 μg/kg · d, whereas the l-T4 was 1.68 ± 0.33 μg/kg · d with a microgram/microgram l-T3 to l-T4 ratio of 0.34 ± 0.05"

which means the dose to achieve the same TSH result, was T4 daydose = T3 daydose/0.34= 3 x T3 daydose, which is the same @Hip quoted.

By the way this study found that the effect of three daily doses of T3 has much more effects on many metabolic parameters (lipid metabolism) than T4.

I noticed that Heart rates were not different (about 80 BPM at rest)
 
Messages
90
I take AM base dose T4 50 mcg and divide Naturethyroid (preferred WP but slow coming back online) AM , 2PM, and 9 PM (1/2 a grain each time).

Splitting doses helped lower my high SHBG somewhat. Paradoxically, dose just before bed helps with sleep.
 

pattismith

Senior Member
Messages
3,926
@Nine lives
if you look at table 2 in the study I quoted below

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3205882/table/T2/?report=objectonly

you will see that 3 doses/day T3 increases less SHBG than 3 doses/day T4....

@raghav , do you take TH to treat hypothyroidism?

T3 should be taken three times a day, this is what showed up in this study by Pr Jonklaas (2016) (below)

Her results (table A) match pretty well with what I noticed when taking T3 with non genomic effect starting an hour later and ended 9 hours after intake.
.........

in this study where they used T3 or T4 with three intakes per day, they found:

"The dose of l-T3 was 0.57 ± 0.08 μg/kg · d, whereas the l-T4 was 1.68 ± 0.33 μg/kg · d with a microgram/microgram l-T3 to l-T4 ratio of 0.34 ± 0.05"

which means the dose to achieve the same TSH result, was T4 daydose = T3 daydose/0.34= 3 x T3 daydose, which is the same @Hip quoted.

By the way this study found that the effect of three daily doses of T3 has much more effects on many metabolic parameters (lipid metabolism) than T4.

I noticed that Heart rates were not different (about 80 BPM at rest)
 
Messages
90
Interesting since natural porcine thyroid has a lot of T4. Will check SHBG again in a couple of months. If still high, one way to go may be smaller T3 only doses.