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!