Letrozole and kidney function

I have been on Letrozole since July 2022. At the start of 2023, I had my regular “bloods” done at the GP surgery (I always had a yearly thyroid and cholesterol check) and was asked to return with a wee sample to “recheck my kidneys”. I did this and was advised “all was okay”. Fast forward to this week … annual bloods again and yesterday I received a text to advise that I now have “Chronic Kidney Disease” … but “not to worry, I will be monitored”. I am currently trying to ascertain what my actual eGFR score was as a bit of Googling brought up the 5 stage chart thing. I have asked for a face to face appointment to discuss all this; whether I will get one is a moot point but in the meantime, has anyone else had this happen and does Letrozole interfere with kidney function? I get hot flushes and a certain amount of muscle joint pain, but I have no desire to stop taking it as I am sure it’s helping to keep cancer regrowth away (and my surgeon was most insistent on this point) but I have another five years to go. Any insight on this topic from other forum members or the BCN nurses would be most welcome.


I’m taking Letrozole but only for 7 weeks. What you have said is concerning as my GP has not mentioned any bloods yet.

Would you be able to call the BCN nurses on 0808 800 6000 to talk this through 9-4 Mon to Fri 9-1 sat?

Thanks for reply, yes I possibly will do that but at present I am still waiting for my actual test results to be provided. Sadly since Covid, our surgery has been fairly useless, they never seem to have any staff, there is only one GP and I haven’t caught a glance of him in years and when I sat waiting for my blood test on Tuesday morning there wasn’t a soul in there.

Try not to be worried about the Letrozole and kidney functions as I am not even sure the two are connected yet. It’s early days for you. I am sure someone else will be along on here to contribute soon and I will update the thread as soon as I get some sense/information from the surgery. It’s ironic that at every stage of my bc treatment I was kept updated about what was happening and, as is normal now, I received a copy of every letter my surgeon and oncologist sent to my GP. Test results are apparently “secret” as you are only ever told “it’s fine”. Well it’s not and if they don’t phone or text me soon I will be going in tomorrow to chase things up.


Had a blood test last week they got it wrong was diagnosed with high potassium kidney damage etc . Turned out blood was slow in syringe and cells damaged . Really stressful but common mistake apparently. Get another test

Interesting! Funnily enough, this was my second appointment as the first time they couldn’t get any blood out. Thanks x

Hi @naughty_boob I think the blood tests that @Moggy_and_Fish_Mum is talking about is the annual blood check for any one taking regular repeat medication to ensure the dosages are correct (by taking annual readings and comparing them to expected ranges). I see that she mentions thyroid and cholesterol checks so that would make sense. I too have had thyroxine for hypothyroidism and atorvostatin for high cholesterol for decades so have had the same annual checks for years. It is not specific to Letrozole and I’m not entirely sure which checks they would do to ensure that one is getting the right dose of Letrozole as we all get the same 2.5 mg.

@Moggy_and_Fish_Mum I get all of my blood test results on the surgery website with explainer notes about the meaning of the results. I recently had the kidney function tests and two of the five came back out of range (creatine below and serum chloride high). I also had the LDH test which came back saying “Abnormal but no further action” :flushed: and reticulocyte count was slightly high. (Also had liver function tests (bilirubin always higher than expected range for me so no panic), B12, D3 and thyroid). I was a tad concerned about the out of range stuff so saw the doctor. She went through every result line by line and explained why everything was fine (didn’t understand half of what she said) even the abnormal ones to do with the kidneys. If you can get to see a GP I’m sure he or she will be able to reassure you. They don’t understand that some of the language that they use which, to them, has a certain pedestrian meaning can make us go WHAT???

I’ve been on Letrozole for 17 months and the only organ that the doctor suggested might be impacted by it is my stomach as I have digestive problems and after a gazillion tests which have produced no overall result she shrugged and said “maybe it’s just the Letrozole”. The funny thing is the digestive problems started before the cancer. Letrozole - forever the villain it would seem.

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Brilliant Tigress, many thanks. Seems like you have a great GP surgery where you are. I have requested access to my test results (which of course you are entitled to by law) and will speak to them (again) when I go in today. And seek an appointment. But what you say has reassured me and I thank you for that. And you are right - I am also on Levothyroxine, statins and Sertraline and the annual check is routine.

The irony is that during the cancer treatment I had a “nice” letter from them sympathising with my diagnosis and offering an appointment to chat about it. I was receiving top class attention from the breast care unit so didn’t need to pursue this but now I want to talk about something ….

They are short staffed there and short of GPs and I get that, so I have no intention of going in with all guns blazing. However, I am going fully armed with every weapon I can think of and they will provide me with my clinical record and give me an appointment to discuss them. I might be a Moggy Mum but I can be a big cat too!

I am lucky with my surgery @Moggy_and_Fish_Mum which is in West London. It is well known in the area for being the best and that brings in excellent junior doctors (registrars) who do 6 or 12 month stints with the practice, which is a bonus. We also have a set of terrific women doctors somehow, who seem to go the extra mile. Having said that, we also have the “you are number 15 in the queue” every time you ring with the predictable 50 minutes hanging on to speak to a receptionist and are lucky to get an appointment (which MUST be booked on line) in less than 5 weeks. Par for the course across the country these days.

It does sound that they will be amenable to your request for an early appointment to discuss your results if they invited you in on diagnosis. You can always lay it on thick and say you were very grateful but, as you had other avenues with the BC nurse, you didn’t want to take up an appointment that would useful to another patient :wink:

A couple of years ago I was diagnosed with chronic NAFLD much to my horror (ok, I am chocoholic :woman_shrugging:) so started eating better and, very importantly for liver and kidneys, drinking 1.5l of water a day. Current liver readings are normal so even IF there is a blip in your kidneys, it is likely to be recoverable.

Good luck at the surgery - give them the metaphorical Puss-in-Boots eyes and if that doesn’t work, show them your claws!

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Thanks @Tigress I re read all the documents regarding Letrozole and it does say it can increase your cholesterol and you should have blood tests. I will check with my GP. I think when I had the leaflet I just skipped over everything.

Yup @naughty_boob it can so worth getting it checked out at some stage. I have upped my statin from 20mg to 40mg just in case. 40mg is the standard dosage I believe but I had half that for years as I was worried about leg cramps (not had any on 40mg so was worried about nothing). Alas high cholesterol is a congenital family problem. My lovely Mum was 5feet nothing and 7st 4lb the whole of her life but had to have statins. I’m always torn between “thank god we have the pills these days” and “not more bloody pills” but largely come down on the former.

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Apparently there’s no link between abnormal kidney function and Letrozole, I had reduced eGFR and urea but eventually normalised. I stopped Letrozole due to side effects

My dad was dead of a heart attack at 49, his brother at 52 so GP thought my high cholesterol was familial unless I was stuffing myself with chips every day. So my statin dose was 40 also and luckily no side effects. Things have moved on … I can now see my test results online and I have an appointment for next Tuesday. I feel a lot more settled now phew! Thanks everyone who took the time to comment, much appreciated xx


Hi sorry to hear you are having gp results problems

First you are entitled to a GP cancer care review. I had mine 7 months after surgery with a specialist nurse practitioner who was excellent. The bcn said they should be done 3 to 6 months into treatment but many GPs need to be reminded/ coerced.

Second, you can get an app on your phone to access your medical records and test results. The NHS app or MyGP or Patient access all work on similar ways. You do need a couple of codes from your GP admin staff to set yourself up and tell them you want your medication and results to be available to you. Then you can see all your test results, medications, vaccinations that the practice put on file. Might help in future if your practice doesn’t print them off for you.

Good luck.

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I had had cancer since May last year and have only seem GP if I am unwell. Will have to prompt them for review. I’m in Wales and we had an NHS app but it’s very limited, prescriptions and allergies. No results which is a shame.

Thank you :smiling_face_with_three_hearts: