Estradiol and IVF: what is it? what does it do Why is it measured? (2023)

WHEN RESEARCHING ABOUT OESTRADIOL I PROBABLY TOOK LONGERfiguring out the pronunciation of the word than anything else in this article - and I'm still a bit confused. All I know is that the "o" at the beginning should be ignored.

You can probably go with one of the following and not be laughed out of space:

• ESS-trade-ee-yall
• EEESS-trade-ee-yall
• Ess-trad-AI-yall

Estradiol is already a minefield, and I haven't even gotten past the word itself.

Let us continue…

What is estradiol and what does it do?

Estradiol is a type of estrogen and a hormone that plays an important role during ovulation. It works in tandem with its best bud FSH (among other hormones) to get an egg into your ovary every month.

Here’s how it works during a “normal” menstrual cycle:

1: FSH is released by the pituitary gland to stimulate growthovoid folliclesin your ovaries. Many follicles are growing at the same time - and the cells surrounding the eggs in those follicles produce estradiol. As a result, the lining of the uterus thickens and prepares to receive the long-awaited fertilized egg in a few weeks.

2: Although many follicles started to develop at the same time, there is only one super impressive follicle that grows faster than all the others.It's known as the "dominant follicle," and the cells around the egg in that follicle produce a ton more estradiol - which in turn sends a signal to decrease the amount of FSH produced. The decrease in FSH has the effect of pacifying all other follicles, allowing only this one dominant follicle to continue growing.

3: Finally, the egg in the dominant follicle is ready to be fertilized.But first it has to detach itself from its follicle and find its way to the fallopian tube - where the sperm can find it.

4: Re-entering the left stage... estradiol.Its levels have been rising all along, and right now we're at 'peak estradiol' - which signals the brain that the ovary is ready to release the egg.

5: To get the process started, the pituitary gland releases large amounts of another hormone called "luteinizing hormone" (LH).acting heads up for the ovary that "IT'S TIME TO RELEASE THE EGG!!!"

6: The egg detaches from the follicle and travels down the fallopian tube, waiting to be fertilized.

(Continue reading this articlehow “normal” ovulation worksfor the full and complete explanation of the whole process.)

So that's what it is and what it does. Next: What do we learn from measuring estradiol levels?

When is the estradiol level measured?

Your estradiol levels will be checked at two important points during the IVF process:

• The first time is as part of yoursDay 3 baseline blood testsbefore IVF begins.
• The second time is during the "ovarian stimulation" phase of IVF.Here is a complete overview of the IVF process.

Some people also have their estradiol levels checked just before starting IVF.

Why are estradiol levels measured before IVF treatment?

Your estradiol levels will be checked as part of your testDay 3 baseline blood testsalong with yoursFSHAndAMHlevels and yoursNumber of antral follicles.

As with FSH and AMH (and your antral follicle count), your estradiol level gives an indication of how many there areovoid folliclesYou have debris in your ovaries - which is important for knowing your chances of pregnancy and the type of IVF protocol you should use. (More on this in the article onthe IVF process from start to finish.)

Your level is calculated in a weird, cumbersome way. Here is the explanation...

By day 3 of your period (i.e. day 3 of your bleeding) your follicles should not have matured or developed enough to start releasing estradiol, so your estradiol levels should be low. Having high estradiol levels this early indicates that something strange is going on with your ovaries.

The most likely "strange thing" concerns youFSH-Level. You see, your FSH levels should also be low according to your blood tests on day 3: FSH stimulates your egg-containing follicles to grow, but only a tiny amount of the substance should be needed for this. If your blood tests show you have high FSH levels, it means you're working extra hard to get your follicles to do itBloom well, start growing- and that, in turn, means you'll run out of eggs (making it harder to get the remaining ones to respond to your requests).

But even if your FSH is working like crazy to achieve some sort of egg growth, your blood tests will be donecouldgive you a misleadingly low FSH result. Why? Because high levels of estradiol artificially suppress FSH levels, leading to a misleading FSH blood test result. (That means your FSH isStrictly speakingthrough the roof, but your estradiol disguises it as part of a "if I go up, you go down" pact they seem to have with each other.)

SO (on the way there, I promise!)...if your FSH levels seem reassuringly low but you're struggling to conceive, your high estradiol levels are signaling you've all been caught.

The estradiol blood test essentially checks that the FSH blood test is telling you the truth.

Another reason for increased estradiol levels is if you still have "active cysts" in your ovaries from previous cycles. The outer covering of a follicle remains after the release of an egg cell - and shortly after ovulation produces the hormones that are needed in the event of pregnancy. Starting fertility treatment while these cysts are still present can mess up your fertility cycle.

What estradiol levels are considered "good" (in pre-IVF blood tests)?

There are no clear cut-offs for normal and abnormal estradiol levels, but doctors usually like to see levels between 92 and 294 pmol/L.

It's also possible to have abnormally low levels of estradiol. These are often associated with people who have PCOS, or hypopituitarism. Women with eating disorders or intense exercise programs may also have a low score. Oh, and levels drop (and stay there) after menopause.

What does it mean if I have high estradiol levels (on pre-IVF blood tests)?

It means the doctors need to take a closer look at your otherTag 3Test results to find out what's going on. If you have a combination of high estradiol and either high levelFSHor lowAMH, this indicates that there are less than ideal numbers of eggs remaining in your ovaries – the cause of this is probably age-related.

To understand the implications of having fewer eggs, keep reading this rather brilliant (if I do say so myself) articleegg quality and quantitywill tell you everything you need to know.

If the cause of your high count turns out to be an "active" cyst (which a scan will confirm), you may need to delay your IVF treatment until the cyst clears.

Why are estradiol levels measured during IVF treatment?

It's designed to make sure you don't fall off the cliff of Ovarian Hyperstimulation Syndrome (OHSS). Basically if your meds are making you growtomany follicles, you are at risk of getting OHSS – an uncomfortable syndrome that is explained in more detailHere.

As we already know, growing follicles produce estradiol, so extremely high levels of estradiol is an indicator that you are producing too much of it. Your estradiol level will be used along with your transvaginal ultrasound scans to determine how many follicles there are.

Read more about the whole IVF process here.

Each large (>15 mm) follicle produces about 200-500 pg/mL estradiol. In an ideal world, IVF treatment results in approximately 15-20 follicles (18-24 mm) and estradiol levels between 2,000 and 4,000 pg/mL. Things get worrisome when you have more than 20 follicles (18-24mm) and an estradiol level between 4,000 and 6,000 pg/mL. doctors donotlike to see more than 30 follicles (18-24 mm) and an estradiol level above 6,000 pg/ml.

It's also possible to have high estradiol levels without a large number of follicles — and that's still an indication that you could get OHSS (although doctors aren't entirely sure why).

What happens if I have very high estradiol levels during IVF treatment?

OfReallyYou don't want to get OHSS, and the good news is that doctors have some ways to make sure you don't get it. Read all about it in this articleOHSS.

Estradiol levels: always the bridesmaid, never the bride

OK, so that analogy didn't work (AT ALL), but the gist of estradiol levels is that whenever we measure them, we feel the need to measure somethingandersat the same time - just to make sure we get an honest picture of what's going on.

But if they artificially suppressFSH levelsso what can you expect? Exactly. No reason to feel sorry for them.