@chorusgirl500 My 18 year old son just went through several rounds of CBCs until one came out normal . This started two years ago. The Jak2 test was negative. Because he has had a normal CBC and negative Jak2 , the hematologist said he did not have PV. He blamed it on the lab. I sure hope he is correct. He also said probably sleep apnea that lowers O2 and causes the body to make too many red blood cells is also a possibility. From what we were told, if he was positive, he could live a normal life.