Polycythemia Vera (PV) is not typically staged in the same way as many other diseases, particularly cancers, as it is a chronic disease and does not spread to other parts of the body. Instead, PV is often classified based on the symptoms and complications associated with the disease. The World Health Organization (WHO) has established diagnostic criteria for PV, which includes both major and minor criteria. A diagnosis of PV is made if either all three major criteria, or the first two major criteria and one minor criteria, are present.
- Major criteria include an elevated red blood cell mass, the presence of a JAK2 mutation, and subnormal serum erythropoietin levels (the amount of a hormone called erythropoietin, in the blood) .
- Minor criteria include bone marrow biopsy showing hypercellularity (an abnormal amount of cells) and endogenous erythroid colony formation (the hormones that stimulate red blood cell production).
Phases of Polycythemia Vera
Polycythemia Vera generally progresses through three phases:
- Proliferative Phase: This is the initial phase of PV, characterized by an increase in red blood cells, white blood cells, and platelets. Symptoms may include headaches, dizziness, and a feeling of fullness in the stomach.
- Stable Phase: In this phase, the disease is controlled with treatment. Blood counts may return to normal and symptoms may decrease.
- Spent Phase: This is the final phase of PV, which occurs in a small number of patients. The bone marrow becomes scarred and can no longer produce enough blood cells, leading to anemia. This phase is also associated with an increased risk of acute leukemia.
It's important to note that not all patients with PV will progress through all three phases. The course of the disease can vary widely from person to person, and treatment can often control the disease for many years.