Polycythemia

Polycythemia

Primary polycythemia/ Polycythemia vera

  • a.k.a polycythemia rubra vera; erythremia
  • common in age 60 – 75
  • overproduction of all three hematopoietic cell lines with predominant elevation in red cell counts
  • mutation in the JAK2 protein which regulates marrow production
  • red cells grow wildly despite a Low erythropoietin level
  • high serum leukocyte alkaline phosphate
features:
  • Headache, blurred vision, and tinnitus
  • pruritus, especially after hot bath (due to histamine release from increased numbers of basophils)
  • HTN, facial plethora, fatigue, Splenomegaly
  • Bleeding from engorged blood vessels
  • Thrombosis from hyperviscosity
Investigation,
  • elevated Hct >60%*
  • low MCV and Low iron (because of excessive usage and production)
  • however, Vit. B12 levels are elevated for unclear reason
  • exclude hypoxia first; normal Oxygen level and *low erythropoietin level in PV
* RCC also has elevated Hct, but the erythropoietin is elevated.
* A small number of patients can convert to AML.
Tx
  • initial 1st line – Phlebotomy and aspirin prevent thrombosis – target Hct 45%
  • Hydroxyurea helps lower the cell count
    • indicated in old age >70 years; has thrombosis; has a platelet count >1500; and has cardiovascular risk factors
  • Allopurinol or rasburicase protects against uric acid rise
  • Antihistamines
  • Interferon alpha may be used in refractory cases
Platelet counts elevate temporarily after spleen removal

Secondary polycythemia
Increased erythropoietin level
2° to chronic tissue hypoxia
 

Kidney cancer is an important differential diagnosis of secondary polycythemia.

Renal Cell Carcinoma is a neoplastic condition that can initially appear with many different paraneoplastic manifestations.

The initial presentation may include hypertension, flank mass, gross or microscopic hematuria, hypercalcemia, fever, weight loss, and/or polycythemia.

Polycythemia may be the presenting sign in 3% of cases of kidney cancer.

Careful evaluation is important in patients presenting with polycythemia and hematuria.

Polycythemia is secondary to a hypersecretion of tumor cytokines, including renin.

The patient’s erythropoietin level is usually high.

Surgical removal of the cancer resolves the polycythemia.