Hi Alleigh,
Good question honey.
I have been on hormones 8 years and now 4 years post op.
I used to give blood regularly, before I transitioned and had well developed veins in my arms. Now when I go for blood tests the Nurses havereal trouble finding them and I spend a great deal of time squeezing rubber balls or having things strapped round my arm so they can find them.
I cannot say this is a defined effect of HRT, but you raise an interesting point.
Buffy