Does high dosage GH ACTUALLY inhibit your thyroid? Read this for the answer

This is a great question and I’ve done researched this exact situation with TSH-T4 reduction on bloodwork when running high dosage GH. My goal is to make this post easy-ish to read even if you don’t have a medical background. This will save a lot of our GH users from wasting their money and stressing out.

Fast answer:
For people who don’t want to read a long post, you’re welcome. If you didn’t have a thyroid problem before you ran higher dose GH, and then once you started running GH your TSH/T4 looks low you probably don’t have a thyroid problem. It’s a false negative from your pituitary gland. You don’t need to take T4. Only take T4 or T3 if you T3 is low. T4 is an in-active hormone so using T3 is more effective to restore normal thyroid function which is controlled directly by T3.

Here’s why for the people who care to know.

-So why does high dosage GH make TSH and T4 thyroid levels appear low? Well it’s simple yet complicated (of course).

-TSH is produced in the pituitary gland, the same place growth hormone is produced. TSH’s job is to tell the thyroid gland to “CREATE MORE T4”. TSH ITSELF DOES NOT do anything other than tell your thyroid to make T4. TSH DOES NOT BURN FAT OR INCREASE METABOLISM. It’s just a messenger.

-If someone takes supra-physiological levels of growth hormone the pituitary gland will secrete somatostatin. Somatostatin tells the pituitary gland that “We have too much active GH in the body, STOP natural production.” Similar to taking exogenous testosterone and your testicles not creating testosterone naturally anymore.

-When the pituitary gland gets the signal to stop making GH there’s an interference with TSH production. This isl because both of those hormones are produced in the pituitary gland.

-Then what happens? Your body stops producing as much TSH. TSH tells the thyroid to “make T4.” So if there’s less TSH then there’s less T4 being produced in your body theoretically. Hence the low T4 on your bloodwork.

-Less T4 means what? What does T4 even do? T4 is an in-active hormone and by itself it does ABSOLUTELY NOTHING WHEN IT COMES TO CHANGING YOUR PHYSIQUE. It has one job - to convert to T3 via ionization using iodine. It does that in the liver and the GI tract. If you have a liver or GI issue you can have a conversion issue causing T4 to not turn into T3 thus causing low T3 in general. There’s auto-immune diseases that can cause a conversion issue as well but I won’t get into that now.

-So let’s say someone has very high T4 or very low T4. They won’t feel any different as long as their T3 is the same. T3 is the ACTIVE hormone. T3 supplies tissues, T3 increases metabolism, improves energy. T3 is what makes you lose body fat. Why do people take T4 then? They’re hoping the T4 converts into T3. If your liver and GI are healthy some of it usually does. If there’s an issue it won’t. Therefore in some people T4 therapy is useless because they’re bad at converting T4 into T3.

-If your bloodwork comes back showing low T4, yet your T3 is still in the normal range DON’T do anything.

-If your T4 and your T3 is low, that’s where you need to take either T4 or T3. T3 being more effective because it doesn’t need to convert into T4 to work. T3 works regardless of your organ health.

-Also, guys who run high dosage GH seem to have a great metabolism. If GH truly inhibited wouldn’t their thyroid they would have a slow metabolism? Exactly.

-Most top coaches who have guys who run dosage GH of 6+IU per day don’t use T3/T4. In some cases they might use a maintenance dosage of 25mcg T3 at the end of prep but it’s not necessary for all.

I hope this helps. Don’t be fooled by confusing bloodwork ever again!

Also, do your damn bloodwork.


I have read this 2x now .
Wish I had seen this 10 years ago .
What I will say is I learned that T3 and T4 has a profound effect on your mood . When I was paying $195 to a TRT Dr ( Everyone in the North Eastern states knows Dr George ?) I thought I could figure out what I needed without bloodwork. lol
I found a sponsor with the combination of t3/t4 . More is better or so I thought . I think by the second day mild depression hit me . I returned to just low dose t3 with GH and mood stabilized.
Thank you Mjk7


I agree blood work is king . But not all the ranges work the same for everybody my body is different and reacts different when my level are high and low in some areas . So the blood helps you figure out your body and where you feel the best


My personally if I’m going to run GH for my competition and my Tsh and T4 labs look off mid cycle I’m not changing anything. But if T3 looked low and my fat loss become very slow (which is unlikely) I would begin to use 25mcg T3 daily.

I do know some people like the 50mcg T4/12.5mcg T3. But again you’re just hoping the 50mcg T3 turns into another 12.5mcg of T3. But at least if it doesn’t you’re still getting some T3 regardless.


Thanks for this. :100::call_me_hand:t4: Ive read up and see a lot of mixed reviews on T4 this T3 that… I guess you have to find what’s best for you and your body…
but without bloodwork being done what are some sides to watch for to know if you need T4? Just curious. Blood work isn’t an issue and can be done at anytime but are there noticeable side effects that will obviously pop up?

Elevated heart rate, shaking, sweating, rapid weight loss. But you need to be a running a lot to get there as a guy. For example over 100mcg a day T3 in a guy.


Damn good info right here. I just bought some T4/T3 combo pills for my wife.

Backstory, about 12 years ago she was diagnosed with Graves Disease so they had to destroy her thyroid. She’s been on T4 since. The problem is in the past 1-2 years her weight has started creeping up so it seems like her T4 dose isn’t working great anymore. My theory is she’s no longer converting the T4 to T3.

I’m anxious to see how she feels on the T4/T3 combo.

She’ll feel much better on either the T3/T4 combo or just T3. You’ll see.

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So she’s currently on 100mcg of T4… I’m thinking continuing on the 100mcg and adding 25mcg T3. Thoughts?

If the gland isn’t working right doing t4 is a waste of time . I’m not the issue in a whole . But if that’s the case t3 is the only thing that will help

Well, the T4 must be somewhat working but losing it’s effectiveness because her levels are still in the “normal” range per her doctor which is why the doctor won’t change anything. Even though my wife has told the doc she feels best when her bloods come back at a certain TSH…
My theory is keep the T4 the same and add T3 in the mix… It’s hard to get my wife to change things that doesn’t come directly from a doc. I’m surprised she’s agreed to this. I’m hoping she’ll feel so much better I can just convince her to eventually ditch the T4 altogether.
Now if I could just convince her to take low dose T… :sob:

Must hormone doctors are clueless brother . I would change it to where she feels good . Just keep a check on it (bloods). We are all different can’t just go by base line stuff .

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Yes sir, completely clueless and as long as your levels are in “normal” range… which is bullshit, they won’t do a damn thing.

The article is good but not sure all the info is required to understand the rational/outcomes of these hormones.

It’s funny I’m reading this post now. I feel like the whole “you have to run t4 with your gh” was a bro science fad for a while and then slowly went away. I love gh and stay on it constantly jus adjust my doses. I jus keep an eye on my insulin sensitivity and so random BLood sugar test . I also run Metformin 2 time daily and everything bloodwork wise is great

I do like pairing metformin with GH. It definitely changed my physique.

I’m not totally sold on adding the T4 for GH but I believe it has something to do with deodinase and the action of turning T4 into T3. If this is the case add 50mcg of T4 to be on the safe side.