Could a small right kidney cause high blood pressure?

Yes: A small kidney is scarred and will raise systemic blood pressure to perfuse itself. Medical management with drugs such as ACE inhibitors or angioplasty may be indicated.

Possibly: A kidney that is small from scarring or a disease process and will raise systemic blood pressure to perfuse itself. However kidney size varies and one may be a little smaller and that may not cause high blood pressure.