Question: I am a male, 35 years old, 220 lbs, non-smoker, don't live at high altitude and no lung conditions.
About 5 years ago, routine bloodwork came back that showed me hematocrit slightly elevated at 51% (ref. range 41-50). My doctor wasn't concerned but I looked at my past blood work and most of the time, my hematocrit was in the 46-48% range. I had a repeat test and my hematocrit was 52%, RBC 5.8 and hemoglobin 17.5 -- all slightly elevated again.
My doctor wasn't concerned but I took it upon myself to see a hematologist. I took my records the hematologist and he said "this does not seem like polycythemia vera but I will test for it to just cover all the bases." He did a repeat CBC, an EPO serum test, a genetic JAK2 mutation test, a JAK2 exon 12 test, and a CALC mutation test.
The EPO serum came back normal at 7 ( reference range: 4 - 27) and all the mutations came back as negative. The CBC did show my hematocrit at 53%, hemoglobin at 18 and RBC at 5.9 though. He said if I wanted assurance, he could order a Red Blood Cell Mass test which is a long test of blood draws that separates the plasma and measures the red blood cell mass... and only a few locations do it. Luckily, there was a hospital by me in NYC that did it. That test came back as "normal red blood cell mass" .
He told me "just do a repeat EPO and repeat CBC in 6 months and make sure you really hydrate during that time". I spent the next 6 months drinking more water than I ever have. When I took the test at the 6 month mark, my EPO was 10 (normal again) and this time, my hematocrit was normal (47%) , hemoglobin normal (16.5) and RBC normal (5.2). He called and said "that is what I like to see. No need to come back."

That was 5 years ago and since then, I've had routine blood tests for other reasons (physicals, etc) and the majority of them all have the same elevated hematocrit, hemoglobin and RBC. I have 2 or 3 scattered time over the years where they come back in the normal range but most of the time, they are elevated. I just had one last week and it came back at hematocrit 53% , hemoglobin 18% and RBC 5.9.
Am I missing something? Could my doctor have missed something?

Thank you, Dr. Puri. One question that I never really had answered was can hydration "mask" polycythemia vera? Could drinking more water than I normally do have artificially lowered my red blood numbers, thus masking PV?
I'm just curious as to why I have elevated numbers if there is no clear cause. Thanks again.