Question
All are true about Polycythemia vera except
| A. | Increased vit B12 |
| B. |
Decrease LAP score |
| C. |
Leucocytosis |
| D. |
Increased platelets |
Show Answer
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Correct Answer � B Explanation |
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Ans. is ‘b’ i.e., Decrease LAP score
Polycythemia vera
- Polycythemia vera is a neoplasm arising in a multipotent myeloid stem cell that is characterized by increased marrow production of erythroid, granulocytic, and megakaryocytic elements.
- This leads to erythrocytosis (polycythemia), granulocytosis, and thrombocytosis in the peripheral blood.
- Polycythemia is responsible for most of the clinical symptoms of polycythemia vera.
- Polycythemia vera progenitor cells have markedly decreased requirements for erythropoietin and other hematopoietic growth factors. Accordingly, serum erythropoietin levels in polycythemia vera are very low, whereas almost all other forms of absolute polycythemia are caused by elevated erythropoietin levels.
Clinical manifestations
1. Symptoms due to polycythemia
- Most symptoms are related to the increased red cell mass and hematocrit, i.e., Polycythemia.
- The elevation of hematocrit is usually accompanied by increased total blood volume, and together these two promote abnormal blood flow, particularly on the low-pressure venous side of the circulation, which becomes greatly distended. That results in –
- Plethora or cyanosis owing to stagnation of deoxygenated blood in peripheral vessels.
- Headache, dizziness, hypertension and
- Diminished vision from blockade of retinal vessels.
2. Symptoms due to granulocytosis
- Basophils secrete histamine that results in –
- Intense pruritis
- Peptic ulceration
- Increased vit b binding capacity because of increase in transcobalamin I & II.
3. Symptoms due to Thrombocytosis
- There is an increased risk of both thrombosis and major bleeding episodes.
Thrombosis DVT, MI, Stroke, Budd Chiari syndrome.
Bleeding Upper GI bleeding from peptic ulcer.
Laboratory features of Polycythemia vera.
| Increased Red cell count (Polycythemia) | Increased Vit B 12 binding capacity |
| Increased WBC count (Leucocytosis) | Increased blood viscosity |
| Increased platelet count (Thrombocytosis) | Decreased ESR |
| Increased Leucocyte alkaline phosphate (LAP) score |
Hyperuricemia due to increased turnover of cells. |
| Increased hemoglobin |
Increased histamine level |