This is Dr. Lam of drlam.com and the Adrenal Fatigue Center.
Today we’re going to talk about the functional differences between T4 and T3 thyroid hormone.
A lot of people are being put on thyroid hormone nowadays when they complain to the doctor
of having fatigue and no other reasons could be found.
The purpose of T4 in the body is to convert into T3, although T4 does have its own function.
T4 is actually not the body’s main hormone although it is the most prominent and most
high in terms of volume.
The workhorse of the body’s thyroid hormones is actually T3, which is the biochemical daughter
of T4.
They both have their own individual purposes, although T4 in general is weaker, much weaker
than T3.
The body makes it in different proportion in order to have the proper use at the right
time in the right place.
So there is functional differences although they both increase metabolism.
And both thyroid hormones have that function as the primary reasons for their existence.
Now when you are given T4, and another trade name is Synthroid, the body converts the T4
automatically into T3, which is also called Cytomel if you’re taking it in the form
of a medication.
Some drugs, such as Armour Thyroid or Nature-Throid comes in a premixed percentage that has the
T4 and T3 in the similar proportion as what is found in the body.
So this attempts to mimic the body’s composition in terms of the circulating T4 and T3.
Most people are started on T4 to begin with, or Synthroid is commonly used in the U.S.
And if things don’t work as well then the doctor can add or switch to T3.
There’s a good reason to do that.
And it’s because, remember we said the T4 is really a precursor to T3 and is not as
strong.
Therefore, you allow the body’s feedback loops to be intact.
If T4 is not working well, or if the body needs more or strong thyroid hormones such
as T3, then they can be added.
In some times the body can have resistance problems and develop many, many issues that
stop the conversion from T4 to T3, and this is another situation where T3 may be used.
Thyroid medication is a very complex subject.
In the case of adrenal fatigue where it can lead to hypothyroid-type symptoms when the
thyroid laboratory could be normal, this can further convolute the picture and can be quite
confusing.
Understanding the role that T4 and T3 makes in the body is very important.
There’s so many signs and symptoms of thyroid problems including dry skin, losing eyebrows
outer third, fatigue, reduced exercise capacity, weight gain.
These are very common presenting complaints to any physician’s office.
And it is very easy and it’s a commonly accepted practice for all the physicians to
give a T4 and T3.
Whether or not you should take it depends on the clinical situation.
So you really need to discuss this matter closely with your doctor.
If your fatigue is due to other reasons other than a primary thyroid problem, such as if
you have anemia, or you have under severe stress, or you have adrenal weakness, then
you don’t want to mask these problems.
You want to basically deal with these issues at the root cause and then you can avoid taking
thyroid medication.
If you take thyroid medication for not the right reasons you can mask the underlying
problem and that could have a long-term and negative effects.
So understanding the thyroid functions, T4, T3, is important.
And you should really talk to your doctor if you are already on, especially if your
dosage had to be increased over time or if you’re not getting the benefit from the
thyroid.
Which all of which can means there’s some other issues going on that may need to be
further investigated.