A Complete Guide to the T3 and T4 Hormones
If you have thyroid problems, it is essential that you understand the T3 and T4 thyroid hormones and why these matter when it comes to managing your health.
Your Thyroid
The thyroid is a small gland found at the front of the neck, just below the larynx. It may be small, but it has a powerful effect on your body’s functioning and metabolism. Thyroid hormone levels affect your heart, body temperature and more. It takes iodine, found in your diet, and turns it into the two primary thyroid hormones: T4 (thyroxine) and T3 (triiodothyronine). T3 and T4 are then released into the bloodstream, where they control your metabolism.
Without thyroid hormones, all of the cells in your body cannot work properly. A healthy thyroid produces T4 with ease and your body then converts it to T3 with no problem either. The majority of hormone produced by the thyroid is T4, but a substantial amount is T3. T3 is also more powerful than T4.
The thyroid doesn’t work in isolation. The pituitary gland identifies when your thyroid hormone levels drop too low and produces Thyroid Stimulating Hormone (TSH). The pituitary gland is effectively the regulator for the thyroid. The pituitary itself is controlled by the hypothalamus. It’s all a finely tuned and complex system!
Why do T3 and T4 matter?
If you’ve got thyroid problems, the chances are you will have been prescribed medication by your GP to manage this, usually levothyroxine. In the UK, these medications are synthetic and replace T4. However, this is problematic for those who struggle to convert this into the active T3.
Both T3 and T4 are made up of a protein and an iodide. T4 has four iodide molecules and T3 has three, giving them their names. A healthy thyroid produces more T4 than T3. This is because when the hormones reach different areas of the body, it is then converted into T3, so it can do its job. You can think of T4 as the stepping stone for T3, or the active thyroid hormone – the one that does the work.
Understanding thyroid blood results
In the UK, thyroid function tests look at your TSH and T4 levels. Sometimes the T4 is referred to as ‘free’ T4. High TSH and low T4 can indicate an underactive thyroid requiring treatment. It’s also possible, with a thyroid function test, to pick up if a problem may be brewing in the future. For example, you may have normal T4 levels, but raised TSH.
Unlike in the US, in the UK you will probably need to specifically request testing of your T3 levels. This can be useful for giving a far more detailed picture of your thyroid’s health. It’s further complicated by the fact that different testing labs will have different parameters for normal ranges, and people have different levels at different ages. It’s therefore worth understanding what is considered ‘normal’.
Normal ranges for free T4 are typically 1.0-3.0 ng/dL and for free T3 are typically 0.25 – 0.65 ng/dL. This is for adults who are not pregnant. During pregnancy thyroid levels increase and so different readings should be considered. Children also have different normal ranges.
What does it mean if your T3 and T4 levels are low?
Hypothyroidism is categorised by low T4 with high TSH. This means the thyroid gland is underactive and isn’t producing enough T4. It can occur for a number of different reasons. In most cases of hypothyroidism, the thyroid gland itself is dysfunctional.
Occasionally, hypothyroidism occurs with normal or lower TSH. This means that the thyroid gland itself is functioning well, but the problem is occurring higher up the messaging system, i.e. from the pituitary.
In hypothyroidism, T3 amounts can be the last to be depleted.
What does it mean if your T3 and T4 levels are high?
Hyperthyroidism is when you have too much T4 and is sometimes known as Graves’ disease. Here blood results will show high levels of T4 and T3, but low levels of TSH.
Is it clear cut?
Unfortunately, there isn’t medical consensus regarding thyroid function test values. This can make it very difficult for the individual, especially if they are experiencing symptoms yet being told that their thyroid levels are ‘normal’. Single blood tests, taken in isolation, without repeated tests and examination of symptoms, can result in subclinical hypothyroidism being missed and left untreated.
How are T4 and T3 replicated in thyroid treatment?
Typically, hypothyroidism is treated using synthetic T4 in levothyroxine. If you’re prescribed thyroid treatment by a UK GP, this is typically what you will receive. This requires the body itself to convert it into the active T3. If your symptoms remain, or are proving hard to manage with T4 alone, then you may have greater success with natural thyroid treatment.
Natural thyroid treatment isn’t synthetic. It uses desiccated porcine thyroid which contains both the T4 hormone and the active T3. There are a number of different manufacturers of natural thyroid treatments which contain T3. These include:
These thyroid treatments most closely resemble human thyroid hormones, and were actually used before synthetic treatments came onto the market. Studies have shown that patients prefer natural thyroid treatments, and can better manage their symptoms with it.
Getting the right T3 and T4 thyroid treatment
If your doctor only prescribes levothyroxine, which is the T4 synthetic thyroid treatment, then you may feel frustrated. However, you can buy the same natural thyroid treatments that are available in the US through International Pharmacy. We give you a broad choice of the main natural thyroid remedies that use porcine thyroid, so that you can benefit from active T3 thyroid treatment. Typically, you’ll find that your doctor is happy to help you manage your treatment, through regular blood tests, but they won’t give you the prescription. Thyroid UK explain why this is, and also detail how some people find they really do need T3 in order to manage their symptoms.
At International Pharmacy, you can choose the right natural thyroid treatment for you.
