T Nation

IGF-1 and Exemestane


Can anyone comment on whether there are connections between IGF-1 levels and use of exemestane/Aromasin? I’ve seen conflicting reports on the way that different AIs affect IGF-1, and I’m especially curious if anyone can share both anecdotal and research-based info on how Aromasin may affect IGF-1. The conflicting reports are that many forum posts say that exemestane raises IGF-1, while others have said that it lowers it. To confound things, on another forum I’ve seen comments that Arimidex lowers IGF-1 while Aromasin raises it. I’d be grateful for any feedback, guidance, etc.

Many thanks!


I unfortunately can’t answer your question, as I don’t know that answer. Although I have a question sort of for you. I know you’re talking about IGF in relation to Exe/Aro but didn’t all the vast majority of online suppliers pull IGF from shelves? I heard through the grapevine that the fed was attacking online SARM providers and the like. Idk if you heard of that or can shed any light, if I’m bothering you or derailing I’ll gladly delete this. It’s to the point where I can get growth hormone cheaper than IGF.

Dear Diary


I haven’t seen that. It’s prohibited to talk about suppliers here but with a quick search, IGF-1 LR3 is definitely available.


Yeah I wasn’t trying to discuss suppliers, nor do I need one. I was just wondering because some of the online companies I used to use for SERMS that used to IGF no longer carry. I was also curious about this attack on SARMS and if it went through. Not that I even use SARMS, just curious.


To go back to the original topic, it looks like in this study (granted it was a 2-drug study) exemestane was associated with a 35% increase in IGF-1 levels.


So based on my own labs here’s what I can say regarding arimidex (I know that’s not the original question but it’s what i can answer right this moment). My pre-TRT labs showed low IGF. After 14 months on TRT and arimidex my IGF nearly doubled. My hypothesis is that any decrease that an AI may cause is absolutely mitigated by the increase you get from testosterone.


Very interesting. What are your new IGF-1 numbers including reference range?

I posted about this because my IGF-1 came back over the range (about 50% above the top of the range) on two separate tests. The 2nd test came back 37% over the top of the range. I’m currently getting evaluated for acromegaly/pituitary adenoma to rule this out, as these IGF numbers are quite high and I’m concerned. I have a first consult with Dr Saya at Defy on Wednesday for my regular TRT stuff and I’ll be talking about this with him, but I have a bunch of diagnostics this week (including an MRI) for the potential pituitary issues. Would appreciate any info you may have about your own IGF levels so I can understand whether TRT plus an AI may be responsible for these abnormal numbers on my end.


202 ref range 120-181


Just to circle back on this, I got the results of my oral glucose tolerance test today. Completely normal at all time intervals, with a fully-suppressed GH level. So whatever the cause of my elevated IGF-1, it doesn’t seem to be a pituitary tumor secreting growth hormone. The mystery deepens!



I am in the same boat however I do not use any TRT or anything in that matter. So far after consultations with dozen doctors and reading all the medical journals I can wrap everything to:

  1. false positive from laboratory, take another IGF-1 test in different laboratory preferably with different assay method

  2. all IGF-1 lab reference ranges should be adjusted to your age, so just keep that in mind :slight_smile:

  3. sometimes just people have high IGF-1 (not sure how reliable this theory is)

  4. diet high in animal-protein can raise IGF-1 levels

ok now more scarier options:

  1. you have early stage of acromegaly, tumor is probably small and this is probably why there is discordance in the IGF-1 and GH values. In most literature I’ve read IGF-1 is typically enough to indicate acromegaly (although there was one study from Brasil I guess where they have spotted the IGF-1 can be elevated in some people – so we are back to square one). So if you need a MRI at this point take the 3T one (because 1.5T can be to low to spot small tumors). Sometimes this state is called “Micromegaly” in literature.

  2. in some cases the tumor is not located in the head area - other locations can be involved lungs, abdomen.

  3. other case: hyperthyroidism

  4. other case: post-radio therapy

Not sure if this helps you at all, probably not. Anyway please let me know if you will figure out anything :slight_smile: peace


What was the reference range on the OGTT you did to check for GH? I’m curious whether yours had the cutoff of 1ng/mL or you used the lower range of 0.4 ng/mL. My test had a lower bound of <0.05 ng/mL and my GH was BELOW that at all time intervals, so it was a very sensitive test compared with the old standard of 1 ng/mL or even the newer tests with a cutoff of 0.4 ng/mL.


I don’t remember the exact OGTT values, however it was correct as it could be.
As for false positive I was rather referring to the IGF-1 testing itself since different laboratories use different methods and hardware.


But that’s the point-- “correct” depends on the test/assay used. If you read the journal articles all of them refer to different lower limits. You could have been “normal” on a particular test and “abnormal” on a different one. My whole reason for mentioning the limit is that a different test with a different assay is going to give a different “normal.”

Anyhow, I just got my MRI report. They only used a 1.5T magnet so I’m going to ask them to repeat, but there was no large/apparent tumor of any kind and the pituitary and sella appear normal.


Let me quote on of the labs instructions:
"Growth hormone should suppress to <0.5 μg/litre in normal people (though a truly normal response is probably well below this level – some suggest <0.2 μg/litre). In acromegaly failure of suppression occurs, and there may be a paradoxical rise in GH in response to the glucose challenge. "

I found my GH test so summing it up, mine GH suppressed to 0.04 μg/litre, meaning it is considered correct by any known reference range - at least appending to my doctor.

Anyway good luck with your tests, this shit is freaking me out. Do you have any other symptoms typical for acromegaly? Do you have oily skin, acne, skin problems? (although this can be related to TRT itself)?


Ah yeah, so you’re like me-- very suppressed GH.

It’s definitely freaking me out too. I don’t have any other “standard” symptoms-- no changes in shoe size, hand size, etc. My face has been on the oilier side but with better skin care that has lessened. I’ve had additional body hair, but I’m Middle Eastern/Russian and have been on TRT for six years, so it’s not a surprise I’ve grown additional body hair. I was diagnosed with sleep apnea as well. All of these have other explanations (my dad had sleep apnea), so they aren’t really pointing to acromegaly.

I don’t have impaired glucose response (my blood sugar on the OGTT followed a perfectly normal pattern over time), no skin tags, etc. I’m a big guy and I’ve had a heavy-ish browline my whole life, so I don’t think that’s an issue. And anyway, I wouldn’t expect to have visible symptoms since I think it’s early if I do have something going on.

I think I’m going to ask my doctor to repeat the IGF-1 level in a few months, and if it’s still elevated, to do another MRI with a 3T magnet and re-evaluate then. What’s your plan?


To be honest I have no idea what to do next. I kinda hit the dead end so I believe the only thing I can do now is to wait, maybe some other symptoms will appear? Doctors kinda shrug me off, as for the symptoms my main problem is stubborn acne and oily face - which seems to be closely related to igf-1 levels by the medical literature. None gives a fuck anyway :expressionless: