Chapter 131 Polycythemia Vera and Myeloproliferative Neoplasms Flashcards
Central role in the pathogenesis of PV?
Mutation of the tyrosine kinase JAK2
JAK2 - leads to EPO sensitivity, apoptosis resistance of erythroid progenitor cells
Most often, PV is first recognized by what presenting manifestation?
Incidentally high Hgb and Hct
Other manifestations:
- Isolated thrombocytosis (Inc Platelet)
- Leucocytosis (Inc WBC)
- Splenomegaly
How does uncontrolled erythocytosis affect the blood?
Causes hyperviscosity
What neurologic symptoms are caused by viscous blood from uncontrolled erythrocytosis?
Headache
Tinnitus, Vertigo
Visual disturbances
TIA
What common vessels are involved in thrombosis caused by PV?
Cerebral
Cardiac
Mesenteric
Obstruction of which vessel in young women may cause catastrophic?
Intraabdominal venous thrombosis
Sudden and complete obstruction of the hepatic vein - raises suspicion and will need workup for PV
Erythema, burning, pain in the extremities is a symptom complex known as?
Erythromelalgia
Primarily involves the lower extremities
Associated with thrombocytosis
Etiology unknown
May sometimes present as digital infarction
First line treatment if erythromelalgia occurs in patients with PV?
Salicylates
Due to large turnover of hematopoietic cells, how does PV affect uric acid?
Causes hyperuricemia with secondary gout and uric acid stones
Hemoconcentration secondary to dehydration, diuretics, ethanol, androgens and tobacco are considered: Absolute or Relative causes of erythrocytosis?
Relative Erythrocytosis
In contrast to other true causes of erythrocytosis, what event in PV can mask the elevated red cell mass?
Expansion of the plasma volume
Therefore red cell mass and plasma volume determination is necessary to establish absolute vs relative erythrocytosis
What syndrome causes relative erythrocytosis due to a reduction in plasma volume alone?
Gaisbock’s Syndrome
also known as stress or spurious erythrocytosis
Only three situations cause microcytic erythrocytosis, namely:
- Beta thalassemia trait
- Hypoxic erythrocytosis
- PV
Differentiate beta thalassemia trait and PV in terms of RDW
Beta thalassemia - normal RDW
PV and Hypoxic - elevated RDW due to associated iron deficiency
A bone marrow aspirate and biopsy is warranted for diagnosis of PV. T/F?
False.
No specific diagnostic information because these may be normal
What assay supersedes all other tests for establishing the diagnosis of PV?
JAK2 V617F assay
What symptom involving CNS can develop in patients with PV (can be a variant of erythromelalgia)?
Ocular migraine
What GI disease is increased in incidence in patients with PV?
Peptic ulcer disease due to H pylori
What is the most significant complication and often the presenting symptom of PV?
Thrombosis due to erythrocytosis
What cut off level of Hgb and Hct in men and women are recommended for PV to avoid complications?
Male: Hgb = 140, Hct <0.45
Female: Hgb = 120, Hct <0.42
What treatment for PV is needed to reduce hyperviscosity by bringing RBC mass into normal range?
Phlebotomy
Periodic phlebotomy needed to induce a state of iron deficiency that prevents accelerated reexpansion of red cell mass
How often is phlebotomy needed once iron deficient state is achieved in patients with PV?
Every 3 months
Treatment for thrombosis due to erythrocytosis?
Anticoagulants ONLY when thrombosis is already present
PT PTT may be falsely low or high due to red cell mass imbalance
What drug may be given to avoid further elevation of uric acid when chemotherapy is used?
Allopurinol
Asymptomatic hyperuricemia (<10) does NOT require treatment
