After Zoladex - Tests for Menopausal Status

Hi All

I’m looking for info and/or advice from all you people who’ve been through this before me!

I had an er+/pr+ BC at age 50 and soon after was put on Tamoxifen plus Zoladex as a belt and braces approach. My menopausal status at the time was unknown due to my Mirena coil. By the time I finish the Zoladex course I will be 53. I was told I would be on Zoladex for two years, then would have blood tests to check my menopausal status, and they would want to see at least 2 or 3 results all confirming I’m post-menopausal, then I’ll go onto Aromatase Inhibitors.

My questions are:
Does anyone know how long it takes for the effect of the Zoladex to clear the system, and therefore how soon it is useful to start having blood tests? And what interval is needed between successive blood tests?

And then how long do you take aromatse inhibitors?

I’d really appreciate any info any of you can offer.

Thanks CC

Hello CC
I am sure that you will get other posts but I wasdiagnosed at 45 ER+, was on Tamoxifen for 5 years, now on AI, Letrozole for 5 years, was originally told 3 years AI but Onc recommends 5 yrs now due to node involvement and ER being 6/8, this last bit of info I have only just learnt. Only another 21 months on AI and counting!


Hi Cheshirecheese

In addition to the support and information you will gain here please also feel free to call the helpline with your query, alternatively you could send an email to our Ask the nurse service, the following link will take you to both:

Here’s the link to the BCC information page about aromatase inhibitors too:

Best wishes


Hi CC. I’m also on Zoladex and Tamoxifen. I can only say what I have been told, as I’m at about the same stage as you.

I didn’t know menopausal status needed several blood tests. I had a hormone blood test before going on Zoladex, because I had not had a period for nearly 2 months, without any obvious reason, - I’d not had chemo, and nobody expected rads to have that effect, so it was thought I might just entering menopause by myself, and therefore not need it inducing!

I never asked for the results of that test because I had a heavy period starting the day before my appt to have Zoladex injection!

I was told I’d have a blood test after 2 years on Zoladex, and that if menopausal, I’d be on AIs for THE REST OF THE 5 YEARS. ie 5 years in total Tamoxifen + AIs.

The information I received from the REACT trial says the same thing, but as with all this BC stuff, I’m sure we are all different and need to be advised by our onc.

Sorry to not be much help. At least I’ve boosted this thread, and I’ll be interested to know the answers as they’ll affect me too!

Thanks for the replies so far.

It sounds like hazelmary and JCJ have been given even less info than I have, which is hard to believe! I would just like to have a plan that says something like:

  1. Have final 4 weekly zoladex jab
  2. Effect of jab starts wearing off, from date X (presumably 4 weeks after the last jab)
  3. Y weeks later have first FSH blood test to check menopausal status
  4. Z weeks after that have another FSH blood test
  5. Continue with the blood tests until 2 or 3 (how many are needed?) all confirm that I am post-menopausal.
    It doesn’t seem too much to ask, but no one is giving me a clear plan, which I find frustrating. Am I alone in liking to know what happens next?!


FSH, LH and oestradiol are not a very reliable way of checking menopausal status and we no longer use it in family planning to determine menopausal status… all it does is tell you what your hormone profile is like on that day… but a few days later and it could be entirely different.

even during a normal menstual cycle there are times in the month when your hormone profile it similar to that of a menopausal women.

however at 53 and having been on zoladex for 2 years i would imagine it would be highly unlikely your periods would come back… the average age for going through the menopause is 51 although some women can go through it much later but if you have an interuption in your menses close to the natural menopause its less likely to return.

if you doc insists on doing a blood test then you would need it repeated probably 3 weekly for about 2 months to make sure its not dropping back to normal.

in family planning we only diagnose somebody as being menopausal over the age of 50 if they have had no periods for 1 year and under 50 no periods for 2 years without the intervention of medication.


Hi Lulu

Thanks for the factual info, that’s very helpful. I was hoping you might be lurking around in the background somewhere!

Having had no periods for over 10 years thanks to medical intervention, and no clues from my Mum’s history, it’s difficult to know if I’m post-menopausal or not. As you say, at 53 it does seem likely, but they want to prove it before I can go onto the aromatase inhibitors.

Does anyone know how long it takes post-zoladex for the effects to wear off? I assume it will tail off quicker if on the 4 weekly version rather than the 12 week one?


It’s so frustrating, I haven’t been able to find any info anywhere about how long it takes for the effects of the Zoladex to wear off. So I’ve followed the sensible suggestion I received from the email advice line here on BCC and have written to my onc to ask him. He’ll probably say that that is what we will discuss at my appointment in October, but I want to know in advance so that I can go armed with the necessary blood test results.

It’s all about taking control of my own treatment as much as I can, rather than turning up and being told what to do!

CC x

Hi again CheshireCheese, I was told by an Onc nurse that Zoladex can take several months to clear the system. Hope that helps?

In case this helps, I had zoladex for two years at the age of 42. After I stopped, it took almost a year for my periods to return (I was still on Tamoxifen this point - but my oncologist had predicted that it would take about this time. I had periods for a few months but they stopped (possibly because I was going through a really stressful time) but have now started again since I stopped taking Tamoxifen (six months short of the five year period)…

Hi Dorsetgirl and Poddle

Thanks for the additional info, but oh dear, not what I wanted to hear! I’d hoped that after the last 4 weekly Zoladex injection it would disappear from my system in a matter of weeks, not months.

Still not had a reply to my letter to my onc - he’s probably not used to patients writing to him for more info in between appointments.

CC x

Hi All
Just reporting back for anyone else who’s been wondering about this question.

I wrote to my oncologist to get more info and he has told me that I should leave at least 3 months after my last 4 weekly injection before having a blood test to assess menopausal status. He said that Zoladex injections can significantly alter the ovarian function (which I suppose is what they’re intended to do) and can give results that are difficult to interpret.

He also said that he would want at least two blood tests at 3 monthly intervals to ensure I am post-menopausal before swiching me to an aromatase inhibitor.

So it’s going to take months rather than weeks, which is a bit disappointing because I wanted to just get on with it, but at least now I know.

CC x

Update - I’m now one week after the last 4 weekly Zoladex injection should be starting to wear off and having hot flushes as bad as when I first started on Tamoxifen and Zoladex two years ago, even though I’m still taking the Tamoxifen.

It’s as if my ovaries are taking the last opportunity to cause mayhem before retiring!

Has anyone else experienced this after finishing Zoladex?

Just in case anyone else has been asking themselves the same question.
I had a blood test exactly 4 weeks after the effect of the last (4 weekly) Zoladex injection should have started wearing off. The results were that my FSH and LH levels were a long way below the normal range minimum. So the Zoladex is still having its effect.
I’ll try another blood test in 6 weeks or so. Thank goodness my GP is being helpful and letting me have the tests done at my local practice, rather than me having to trek to the hospital each time, as suggested by my oncologist.

Thanks CC for keeping us updated. I’m wondering how long I’ll have to wait. I have the 3-month injections (12 weeks actually) so I’ll probably have a blood test at least 4 months after last injection and then 3 months after that? I only started in May this year, so a long way to go yet!

Keep us posted.

I too was er/pr positive, had Mirena coils for 20 years and had last one removed when I was diagnosed at 51. No idea whether I was post-menopausal or not as had no periods in those 20 years (bliss!). So, I was put on Tamoxifen (as that works on both pre and post menopause). 5 months later I developed a blood clot from Tamoxifen in my jugular vein, so was taken off Tamoxifen.
I had three blood tests over a few months and my onc said that my FSH levels were so ‘convincingly’ in the menopausal zone that she’s put me on Arimidex (Anastrozole) - which doesn’t cause blood clots. I’m on this for 5 years.
Cheshire Cat, Is it not feasible for you to go on Tamoxifen again? It will do the same as Anastrozole, but will cover you in case you haven’t gone through menopause. I only changed due to the blot clot.


I also had the 12 weekly injections for most of the two year period, but chose to have the 4 weekly ones towards the end of the two years in the hope that the effects would tail off more quickly than the 12 week one. Might be total rubbish, but that was my thinking.

Hi Annie22

Like you, part of the mystery of my menopausal status is caused by having had a Mirena coil and therefore no periods for many years. I too had mine removed when I was diagnosed, at 50, but it leaves me with no real clues except I was starting to get hot flushes the natural way! On the assumption that I wasn’t yet fully menopausal I was put on Tamoxifen plus Zoladex for two years, after that to be checked for menopausal status, which is where I am now, hence my questions. I’ve finished the Zoladex but still taking Tamoxifen, so at least I have some hormone type protection against the BC.

Another update for anyone in a similar situation.

My blood tests are still showing FSH levels off the bottom of the normal, natural scale, so the Zoladex is still having its effect. I’m due to have another blood test at the end of January, so I’m hoping things might be starting to show signs of change by then.

In the meantime I’m finding that the cotton wool brain is improving, although sleep is still a problem. It’s difficult to identify what is due to the continuing Tamoxifen and what is due to my age - 53. A lot of the symptoms I’m experiencing, such as brittle nails, and a reduced libido, might be just normal for my age.

Thanks for the update. I’m a way behind you. 7 months into Zoladex. My onc told me to take over the counter calcium supplements for my brittle nails.

Thanks JCJ, that sounds a good idea.