Polycythemia Vera
Polycythemia vera is also known as primary polycythemia, erythremia, polycythemia rubra vera, splenomegalic polycythemia, and Vaquez’ disease. A chronic, myeloproliferative disorder, polycythemia vera is characterized by increased red blood cell (RBC) mass, leukocytosis, thrombocytosis, and increased hemoglobin concentration, with normal or decreased plasma volume. It usually occurs between ages 40 and 60, most commonly among males of Jewish ancestry; it seldom affects children or blacks and doesn’t appear to be familial.
The onset of polycythemia is gradual, and the disease runs a chronic but slowly progressive course. The prognosis depends on age at diagnosis, treatment used, and complications. Mortality is high if polycythemia is untreated or is associated with leukemia or myeloid metaplasia.
Causes
In polycythemia vera, uncontrolled and rapid cellular reproduction and maturation cause proliferation or hyperplasia of all bone marrow cells (panmyelosis). The cause of such uncontrolled cellular activity is unknown, but it’s probably the result of a multipotential stem cell defect.
Complications
Hyperviscosity may lead to thrombosis of small vessels, with ruddy cyanosis of the nose and clubbing (stunting) of the digits. Further thromboembolic involvement can lead to splenomegaly, renal calculus formation, and abdominal organ thrombosis.
Paradoxically, hemorrhage is a complication of polycythemia vera. It may be due to defective platelet function or to hyperviscosity and the local effects from excess RBCs exerting pressure on distended venous and capillary walls.
Cerebrovascular accident (CVA) may also complicate the disease. As well, incidence of peptic ulcer disease is four to five times greater in patients with polycythemia vera than in the general population.
Assessment
In its early stages, polycythemia vera may produce no signs or symptoms. However, as altered circulation (secondary to increased RBC mass) produces hypervolemia and hyperviscosity, the patient may report a vague feeling of fullness in the head, rushing in the ears, tinnitus, headache, dizziness, vertigo, epistaxis, night sweats, epigastric and joint pain, and visual alterations, such as scotomas, double vision, and blurred vision. He may also report a decrease in urine output, possibly due to increased uric acid production.
Late in the disease, the patient may report pruritus (which worsens after bathing and may be disabling), a sense of abdominal fullness, and pain, such as pleuritic chest pain or left upper quadrant pain. (See Clinical features of polycythemia vera, page 728.)
Diagnostic tests
Laboratory studies confirm polycythemia vera by showing increased RBC mass and normal arterial oxygen saturation in association with splenomegaly or two of the following:
platelet count above 400,000/mm3 (thrombocytosis)
white blood cell (WBC) count above 10,000/mm3 in adults (leukocytosis)
elevated leukocyte alkaline phosphatase level
elevated serum vitamin B12 levels or increased B12-binding capacity.
Another common finding is increased uric acid production, leading to hyperuricemia and hyperuricuria. Other laboratory
results include increased blood histamine, decreased serum iron concentration, and decreased or absent urinary erythropoietin. Bone marrow biopsy reveals panmyelosis.
results include increased blood histamine, decreased serum iron concentration, and decreased or absent urinary erythropoietin. Bone marrow biopsy reveals panmyelosis.
Clinical features of polycythemia vera
| ||||||||||||
