Sorry to hear about
your Dad's dx!
I wasn't familiar with it until I Googled a bit and found this:
www.mayoclinic.org/diseases-conditions/polycythemia-vera/basics/symptoms/con-20031013And, according to the site, the risk for polycytemia vera increases with age:
www.mayoclinic.org/diseases-conditions/polycythemia-vera/basics/risk-factors/con-20031013Is Mayo off with this like they are with Lyme?
No matter what, I hope you get some answers soon and, most importantly, that your Dad fares well with everything!