Do NDT Medications (Armour & NP Thyroid) Contain T2?

T2 remains the ingredient that people ask me about the most. 

And because it’s relatively new to the thyroid-support scene, it’s also the ingredient people are most confused about. 

One question I get all of the time is this: 

“Can (or should) T2 be taken if I’m already taking an NDT thyroid medication like Armour Thyroid or NP Thyroid?”. 

The reason this question is so common is that most thyroid patients are operating under the assumption that T2 is already found in NDT. 

In fact, the presence of T2 is why many integrative doctors (and thyroid patients ^[1]) prefer NDT formulations over synthetic alternatives like levothyroxine. 

So doesn’t that mean you don’t need to take T2 if you are using one of these medications?

Nope. 

Here’s why: 

#1. T2 is probably in NDT but we don’t know for sure

Despite the fact that pretty much everyone ‘knows’ T2 is found in NDT, I’m aware of zero evidence to prove that this is actually the case. 

There’s absolutely no mention of it on the official Armour Thyroid United States Prescribing Information page (USPI) and it’s certainly not on the official ingredient list. 

For reference, here’s what’s included (officially) ^[2]: 

• Liothyronine (T3)
• Thyroxine (T4)
• Calcium stearate
• Dextrose
• Microcrystalline cellulose
• Sodium starch glycolate
• Opadry white

Does that mean it’s not actually in there? Not necessarily, because, given that NDT is manufactured from the thyroid gland of pigs, it’s likely that some T2 gets caught up in the process. 

Doctors and patients alike just assume that it must be in there given its sourcing and manufacturing and why else would thyroid patients prefer it over synthetic alternatives? 

If you were to ask me, I would suggest that there is probably some T2 in each dose of NDT but this leads to the next problem…

#2. T2 Content in NDT Is Not Standardized

Let’s assume, for a minute, that T2 is actually found in NDT, doesn’t that mean we are out of the woods? 

Nope. 

Because, even if that were the case, we know that the dosing wouldn’t be standardized. 

What does standardized dosing mean, you might ask? 

It’s the process by which manufacturers ensure that each dose of NDT contains the stated amount of T4 and T3 in each lot. 

This is required because the exact amount of thyroid hormone found in any particular pig’s thyroid gland will differ from one pig to the next depending on their age, size, genetics, and many other factors. 

If the T3 and T4 dosing weren’t standardized then the actual amount of thyroid hormone that you’d get from each dose would vary from lot to lot. 

And, this is simply not allowed to happen, for obvious reasons. 

So the manufacturers standardize the dosing of T4 and T3, but they DON’T standardize the dosing of T2. 

So even if it were to contain some T2, the amount would vary from lot to lot which means you can’t reliably count on it. 

Which leads us to problem #3…

#3. Why NDT May Not Supply Enough T2

In order to feel better on any thyroid hormone, you must be taking enough of it. 

You probably know from experience what it feels like when your thyroid medication is underdosed as you’ve probably experienced the weight gain and fatigue that tends to accompany it. 

Dosing T2 is no different than dosing T4 or T3, you must get enough of it. 

And from what we know about T2, that means a dose of around 100 to 200 mcg per day. 

There’s some controversy about dosing, by the way, but the key is to stay under 300 mcg per day ^[3] (you can read more here if you’d like). 

So if T2 is present in NDT, how much would it probably contain? 

The answer: 

Not very much. 

We don’t have any data to show the concentration of T2 in various tissues in the body, but we do know that it’s primarily created from the breakdown of T3. 

And this breakdown occurs in peripheral tissues outside of the thyroid gland. 

When combined with the non-standardization issue, it’s easy to see a situation in which each lot of NDT contains very little active T2. 

This is to say nothing of the difference in biological activity of the various T2 forms, which also would play a role here as well. 

It’s impossible to know how much is found in each lot of NDT without testing, but I would estimate the T2 concentration to be around 1-5 mcg making it anywhere from 20 to 100x less than the recommended dose of 100 mcg per day. 

Should you Add T2 to your NDT Medication?

Probably, but it’s not always needed. 

Whether or not you personally should take T2 depends more on your symptoms and your thyroid lab tests than whatever thyroid medication you are currently taking. 

If you have what doctors refer to as normal thyroid lab tests, but still experience many of the symptoms of hypothyroidism then adding T2 to your regimen is probably a good idea. 

If your symptoms are controlled, if your thyroid lab tests look good, and if you are feeling pretty close to 100%, then there’s no real need to add T2. 

If you do opt to use T2, here’s what I’d recommend: 

In capsule form, 100 to 200 mcg per day (remember to stay below 300 mcg per day to avoid side effects). 

In cream form, 25 to 50 mcg per day (topical T2 is roughly 2-2.5x more potent than oral capsules so take this into account when avoiding the 300 mcg per day limit). 

Unlike other thyroid support supplements, T2 can be taken at the exact same time as your thyroid medication without the need to separate them. 

If this is your first time hearing about T2 and you want to learn more about its unique benefits on metabolism ^[4], cholesterol ^[5], and weight then I’d recommend checking out this article next. 

Scientific References

1. Hoang TD, et al. (2013). Desiccated thyroid extract compared with levothyroxine in the treatment of hypothyroidism: a randomized, double-blind, crossover study. The Journal of clinical endocrinology and metabolism. doi:10.1210/jc.2012-4107.

2. AbbVie (2024). Armour Thyroid (thyroid tablets, USP): Prescribing Information.

3. Hernandez A (2015). 3,5-diiodo-L-thyronine (t2) in dietary supplements: what are the physiological effects?. Endocrinology. doi:10.1210/en.2014-1933.

4. Senese R, et al. (2018). 3,5-Diiodothyronine: A Novel Thyroid Hormone Metabolite and Potent Modulator of Energy Metabolism. Frontiers in endocrinology. doi:10.3389/fendo.2018.00427.

5. Goldberg IJ, et al. (2012). Thyroid hormone reduces cholesterol via a non-LDL receptor-mediated pathway. Endocrinology. doi:10.1210/en.2012-1572.