Antagonistic

The ultrasound today seemed to go fine. Lefty is at 17 mm, with Righty lagging behind… still measuring 11 mm. (Dr. Y also measured a third at 8 mm, but didn’t say anything about it.) C and I think that Dr. Y was disappointed with Righty’s slow growth, but felt sorry for us and refrained from saying anything… He recommended continuing stims + Antagon for a couple more days to give them more time to grow. He’d like Lefty to be at 20 mm for retrieval.

The next ultrasound will be Wednesday, with tentative retrieval on Friday – possibly later. Back when we started the cycle, Dr. Y said that it will be good if we can get a couple extra stim days prior to retrieval, so I’m going to stick with that and say this is a good thing…

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So, Antagon

I’m on day 3 of Antagon (aka ganirelix), which I inject into my belly every morning by way of a prefilled syringe with an annoyingly dull needle. (It doesn’t hurt that much, but it actually bounces off of my skin if I don’t shove it hard enough!) Aside from looking like a human pincushion, I haven’t observed any side-effects.

Despite my disappointing Saturday, I didn’t want to put off writing about Antagon for too much longer, since it is actually the drug that I find the most interesting, but first:

I am NOT an endocrinologist, or any kind of medical professional! This blog does NOT purport to offer medical advice, medical opinions, or recommendations. Please take this for what it is – the ramblings of an infertile woman trying to make sense of her complicated treatment protocol!

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Before explaining what Antagon does, it’s probably worth reviewing how this whole sex hormone signaling cascade is supposed to go normally.

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First, my brain sends a signal to my pituitary, which in turn sends a signal to my ovaries, which in turn make estrogen, grow eggs, and ovulate.

The ‘signal’ that my brain sends to my pituitary is carried by a peptide hormone called gonadotropin-releasing hormone (GnRH; also known as luteinizing hormone-releasing hormone or LHRH).

The ‘signal’ that my pituitary sends to my ovaries is carried by two proteins – our old friends FSH and LH. Normally, FSH stimulates one or two of the follicles to grow and develop into a single mature egg. LH (released in a surge) signals the ovaries to ‘drop’ the mature egg.

Of course, in the case of IVF, we don’t want to just have one mature egg, and we don’t want to have it get released before we are good and ready for it.

Here’s where Antagon comes in.

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As its name suggests, Antagon (aka ganirelix) is a GnRH antagonist, which means that it looks a lot like GnRH, but it doesn’t act like GnRH. You can see this if you look at the chemical structures of the two (below). Antagon is about the same size and shape as GnRH; it has similar atoms and functional groups (I highlighted the differences in red for your convenience). As a result, it can fit into the same tight spaces that GnRH can fit into – like the inside of the receptor protein ‘switch’ that GnRH normally turns on to make the pituitary send its signal…

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While Antagon looks like GnRH, it doesn’t act like GnRH. So when Antagon fits into the GnRH receptor protein, it doesn’t actually flip the switch ‘on’.

To pick another analogy, GnRH is the key that opens a lock on the pituitary gland. Antagon is like another key that fits into the same keyhole…but doesn’t open the lock. Having lots of Antagon around filling up keyholes makes it really hard for GnRH to actually turn any locks. (In biochemistry-speak, Antagon is a competitive inhibitor.) The effect is the same as if we had somehow removed all the GnRH from the system.

Without GnRH stimulating the pituitary gland, the pituitary gland doesn’t produce LH (or FSH, but we’re more concerned with LH at the moment), and we don’t get the surge, and ovulation is prevented (left panel, below).

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What about Lupron?

Interestingly, using a GnRH antagonist isn’t the only (or even the most popular) option for preventing ovulation.

The other, more common, method involves using a GnRH agonist (such as Lupron, aka leuprolide). A GnRH agonist both looks and acts like GnRH.

Lupron has a chemical structure that is even closer to that of GnRH. In fact, they differ by only one amino acid (in blue on the previous chemical structure drawing). Lupron also flips the GnRH receptor protein ‘on’…and keeps it on for longer than GnRH does.

But I thought we were trying to prevent GnRH from sending its signal?

The initial response of the agonist is to increase the GnRH signal – the opposite of what we want. But we’re counting on what happens next. All this signaling is very carefully regulated, so after a few days of having its GnRH switch frozen in the ‘on’ position, the pituitary figures out that something is wrong. It absorbs the GnRH receptors (the keyholes) from the cell surface, and all further signaling in the pathway gets shut down (above right).

It’s like the sirens go off, red lights start flashing, and the pituitary says “TERMINAL ERROR DETECTED. COMMENCE SYSTEM SHUTDOWN.

With the signal shut down, the pituitary doesn’t continue to make LH, and ovulation can be prevented until we’re ready for it.

What does DOR have to do with it?

Despite sounding more complicated, the agonist protocol is the more commonly-used option, or ‘plain Vanilla IVF’ if you prefer, and works well for the majority of IVF patients. However, some recent studies seem to suggest that using an antagonist might be better for poor responders (like people with diminished ovarian reserve). I think this is still pretty controversial, though.

I think the theory is that for DOR patients, the traditional agonist long protocol suppresses signaling for too long and gets in the way of recruiting the already-poorly-responsive eggs. For the agonist protocol to work, the agonist has to begin to be administered relatively early – before there are any follicles ready to drop (otherwise the initial burst of LH & FSH might trigger ovulation before the desired ‘System Shutdown’), so things are shut down for a relatively long period. By contrast, the antagonist can be administered later in the cycle, for just a few days.

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Whatever the reason, I’m gambling on the short, antagonist protocol. Odds are that I’m going to lose this poker hand, but dammit, I am not folding!

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Stims

Yesterday at 7:45 am I had my first IVF monitoring appointment. Since Kaiser doesn’t cover IVF, Dr. Y does all his IVF appointments in the early morning, across town from his main office. Lucky for me, this is only about 10 minutes from my house. (The Kaiser office is about 10 minutes from my work, so it’s been pretty convenient all-around.) I liked my new clinic. The waiting room looked much nicer than the Kaiser facility: lots of good magazines, friendly staff, and a beautiful aquarium. I sat and watched the fish eating their breakfast while C studied his iPhone.

And… my follies are growing, but slowly (which Dr. Y insisted isn’t necessarily a bad thing). The biggest one measured 8 mm. Estradiol level was 83. Dr. Y said to keep taking the same dose of Clomid & Menopur (and dexamethasone, although he didn’t mention that), and to come back on Saturday.

Oh, and we paid the first big bill: $10,115 “Global Fee” for IVF + ICSI. This amount covers all the monitoring appointments and labs, the egg retrieval, and the embryology part. The Global Fee does NOT cover meds, “Embryo Banking” (freezing and storing the embryos), or frozen embryo transfer, so a complete account of the full cost will have to wait.

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Given where I’m at in my cycle, it seems like my stims would be a good science topic for today, but first the usual:

I am NOT an endocrinologist, or any kind of medical professional! This blog does NOT purport to offer medical advice, medical opinions, or recommendations. Please take this for what it is – the ramblings of an infertile woman trying to make sense of her complicated treatment protocol!

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So, stims…

My ovarian stimulation regimen is low-dose menopausal gonadotropins (Menopur, 150 IU), and clomiphene (Clomid, 100 mg). The goal is to get my ovaries to produce not one but several large, mature, healthy eggs. To understand how these drugs are supposed to accomplish this goal, it would probably help to provide some background. And I feel the need to point out, once again, that I am not an expert. (This blog is not called ‘the infertile endocrinologist’! But if you find a blog with that title, please let me know. I’d love to read it.) So anyway, here’s how I think it works:

Sex hormone signaling 101

Normally, when my body wants to produce estradiol (the most important of the estrogens), my brain sends a signal to my pituitary gland. The pituitary responds by sending a signal to my ovaries, which respond by doing a bunch of things, including making estradiol. The estradiol itself acts as a signal that travels around and tells various body parts to do things.

The carrier pigeons transmitting all these signals are hormones. So, more precisely, my brain produces a hormone called luteinizing hormone releasing hormone (LHRH, also known as gonadotropin-releasing hormone or GnRH), which travels to my pituitary and tells it to produce two more hormones: luteinizing hormone (LH) and follicle stimulating hormone (FSH). These hormones travel to my ovaries and stimulate them to do a bunch of things – like grow eggs and make estradiol…which itself helps to prep the uterine lining, and so on.

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Feedback

As the level of estradiol increases, it circulates through the bloodstream and some of it reaches my brain. Once there, the estradiol tells my brain to stop sending the signal to make more estradiol (in other words, to stop making LHRH). This is a natural “negative-feedback loop”.

Estrogen signaling under the influence

While I’m on my stims, the goal is to get lots of follicles to grow at once. This takes high levels of FSH in there, for an extended period of time. There are two main ways of doing this:

  1. Make more of my own FSH. This is what Clomid aims to accomplish. Clomid blocks estradiol from telling the brain to STOP making LHRH. In this case, two wrongs do make a right, and blocking a stop signal is effectively the same as telling the brain to GO! The brain makes LHRH, which stimulates the pituitary to make LH and FSH, which stimulates the ovaries to grow follicles. Nice.
  2. Add in FSH from the outside. This is what I’m doing when I inject Menopur into my belly each night. Technically, Menopur is a mixture of both FSH and LH, but I think FSH plays the bigger role in follicle development (at least, that’s what its name would lead me to believe…)

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The downside of Clomid is that it doesn’t just block estradiol from talking to my brain. It blocks estradiol from talking to anyone…including my ovaries and uterus (who it’s supposed to tell to start prepping the uterine lining for implantation and making lots of sperm-friendly eggwhite cervical mucus). Clomid steals the entire message from the estradiol carrier pigeon.

Enter my weird protocol. Since the Clomid will prevent my uterine lining from being ‘embie-proofed’ in time for transfer this month, we’ll flash freeze those little guys (hopefully lots of them!) and let them chill for a month. This should give me time to do some nesting and get everything nice and ready to welcome the little tykes!

Why such a low dose of Menopur?

It seems counterintuitive that I would be using a low dose of Menopur, since the conventional wisdom is that patients with diminished ovarian reserve are generally less responsive to stims, and should therefore need more stims… For reference, I used 300 – 375 IU (4 or 5 vials) per day for my IUI cycle…more than twice as much as I’m using for IVF. From what I can tell from my limited reading of the literature, it sounds like for DOR patients with few eggs that are available for stimulation, adding more stims doesn’t increase the number of eggs recruited…and might harm egg quality.

Why Clomid?

I haven’t been able to find a clear reason why Clomid is a good choice in my case. The best I can think is that maybe in poor responders using two strategies for increasing FSH levels will work better than just one? Obviously, the fact that we aren’t doing a fresh transfer is a large part of why Clomid becomes a viable option.

What I know for sure

Clomid plus low-dose Menopur is much cheaper than the high-stims alternative.

Aside from a small crop of pimples on my forehead (which I’m guessing is due to the dexamethasone), I haven’t noticed any side-effects so far. I’m grateful for this!

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That’s where we are for now! We’ll see how the follies are doing bright and early Saturday morning!