I get a lot of questions from women who have a TSH
level in the upper range of normal between 2.5 and 4
and we're told that they should start taking thyroid hormone medication
like Synthroid to improve their chances for
IVF success, increase their overall fertility
or reduce their risk for miscarriage. Is this something you should do?
First, a little background. Everybody has a thyroid gland.
It's located right here in the front of your neck. The thyroid produces hormones
which affect every body process. The two main hormones
produced from the thyroid are referred to
as T4 and T3. Problems can occur if your thyroid produces too much or too little
of these hormones. This is known as hypo or hyper thyroidism
Hypothyroidism is very common in women.
How can you tell if you have hypothyroidism?
Well, the thyroid is controlled by a hormone from the pituitary gland called
TSH or thyroid stimulating hormone. TSH blood
tests are by far and away the most sensitive
and accurate way to determine if you have a
thyroid problem. If your thyroid is not producing enough
thyroid hormones, your TSH blood level will go up.
A TSH level between 0.4 and 4 means your thyroid is functioning
normally. If your TSH level is persistently higher
than 4, then you have hypothyroidism. This group
of women should be treated with thyroid medication.
Should you be treated if your TSH level is below 4?
Let's look at the evidence for IVF. In 2011,
doctors from the National Institutes of Health looked at over 1200 women
who were undergoing IVF and who had their TSH levels measured
before starting treatment. They divided them into two groups based on their TSH
level. The first group were women with a TSH
between 0.4 and 2.5 which I will call the "low normal" group.
The second group are women with a TSH between 2.5 and 4 which I will call the
"high normal" group. This is the group that some have claimed
will reduce IVF success and should take thyroid
hormone medication. How did these two groups compare when
they did IVF? It turned out that they were identical
in almost every way imaginable: they used the same amount of fertility
medications; retrieved the same number of eggs;
and had the same fertilization rates. For those women that had embryos transferred,
the pregnancy rates were the same, the miscarriage rates were the same
and the live birth rates were the same. Let me say that again.
Women in the high normal TSH group: those with a TSH between 2.5 and 4,
had IVF babies at the same rate as women with a lower TSH.
What if you have infertility and you're not doing IVF?
Another study collected data on over 1600 infertile women.
They also divided the women into two groups based on their TSH level.
They also found no difference in the odds of conceiving
miscarriage or live birth when they compare the low
normal and high normal groups. What if you don't have infertility
but have a history of miscarriage? This study looked at over 1200 women with a
history of pregnancy loss and who were trying to become pregnant.
The study found that women with a TSH greater than 2.5 did not have a longer
time to pregnancy, did not have a higher miscarriage rate
and did not have a reduction in their live birth rate. Our InfertilityTV
Bottom Line is this: If you are trying to conceive and your
TSH level is between 2.5 and 4 - Don't stress!!!
This means your thyroid is working normally you will not have more trouble
getting pregnant and you will not have a higher chance
for miscarriage. If you are doing IVF, you will do just as
well as women with a TSH less than 2.5. Do not agree to take
thyroid medication if your TSH level is in this range.
You do not need it! Over treatment of the thyroid is not the only
incorrect recommendation you'll find. Check out this playlist for other
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