May HGH cause Gyno?
 

I've heard about this a few times.
How is this explained?

The problem is that occasionally exogeneous human growth hormone has been known to raise prolactin, Both prolactin & progesterone can lead to abnormal breast tissue but prolactin leads more quickly to excruciatingly painful lactation of a clearish liquid. HGH may cause excess prolactin, just like Tren can. The best response to prolactin is Dostinex.

It may not raise prolactin but it has a similar effect on prolactin receptors:

"Synthetic HGH is comprised mainly of the 22Kda (kilodalton) isoform. Natural HGH the body produces is comprised of a multitude of different HGH isoforms with different binding affinities. The 22Kda isoform makes up the majority of monomeric HGH the body produces, yet is still a very small total percentage compared to the ratios the pituitary releases.

22Kda GH has an extremely high binding affinity to the extracellular prolactin receptor domain (PRL-R). To a greater extent than 20Kda HGH or other HGH dimers, tetramers, etc.
This means that synthetic 22Kda HGH WILL activate the PRL-R just as prolactin would.
So, it is not an increase in prolactin, but rather the direct HGH affinity for the prolactin receptor that causes the sides attribited to prolactin induced gyno."

if it does, then you might be in trouble relating to other bodybuilding compounds.

as far as I know there are 3 ways for this to happen
1. as CC said, all staff related to prolactin
2. HGH may be not real, it may be HCG, a pregnancy tester would do the job here.
3. HGH is known to make things grow if I can say so and so it can affect the gyno which alredy existed.

I would start with checking if HGH is real.