IGF-1 levels are not very informative in people over 50 years old due to binding proteins.

“that igf-1 particularly is is probably not that informative in people particularly you know once you get past 50 years 50 years is arbitrary but that's kind of where i would i would put the number”

“cuz a lot of people won't even measure the free levels of, you know, like the IGF-1, the, you know, the T3, like you'll, you know, some of this stuff gets like hyper nuance when you get into what hormones are actually bound up that you don't realize. Um, estrogens, DHT, etc.”

“And these binding proteins also exist for other hormones in the body cuz they all function in similar ways through cargo systems and transport mechanisms in the body. Like you will have binding proteins for IGF-1, you'll have binding proteins for thyroid hormones. Like it's not uncommon to see people with like normal on paper levels for certain hormones, but then when you dig deeper, all the free hormones are like proportionally horrible because they're all bound like the the total production looks okay, but it's cuz it's factoring in all these like bound up hormones that are in use like unusable essentially.”