I can go to a endocrinologist and test my igf-1 levels.
This is what he said:
Having an HGH kit directly tested for purity is virtually impossible (reliably) anywhere, and in practice, it's so expensive and cumbersome that it's pointless. Besides, you still won't know anything about the next vial from the same batch. A good option is to use it for a few weeks and then have your IGF-1 measured (preferably as a baseline measurement beforehand), plus a GH level about 4–6 hours after the injection. That way, you can immediately see if the product is working as intended.
💯
There are multiple false positive scenarios for hGH with HPLC only tests.
Better results can be obtained in combination with mass spectrometry or reverse phase HPLC (finnrick uses this, not sure what Janoshik does).
A purity test with HPLC combined with bloodwork for the impact on igf levels seems to be the golden standard to verify HGH quality.