Polycythemia refers to an increased hemoglobin concentration and/or hematocrit in peripheral blood.
For Diagnosing the specific cause of polycythemia follow these 3 steps:
STEP1: First check for RBC mass
1)Elevation of Hgb and/or Hct due to a decrease in plasma volume alone (ie, without an increase of the RBC mass) is referred to as relative polycythemia.
STEP2: To diagnose the causes of absolute polycythemia. Check for EPO levels
1)Primary polycythemia is caused by a mutation in RBC progenitor cells that results in increased RBC mass. So there is a decrease in EPO levels. Ex: polycythemia vera (PV)
2)Secondary polycythemia refers to an increase of RBC mass caused by elevated serum EPO. Most often, this is due to an appropriate physiologic response to tissue hypoxia, or by autonomous EPO production(eg, an EPO-secreting tumor)
STEP3: To diagnose the causes of secondary polycythemia. Check PaO2 and SaO2 levels
1)If PaO2<65% and SaO2<92% then it is because of chronic hypoxia due to high altitude, COPD, Smoking, etc.
2)If PaO2 and SaO2 levels are normal then consider EPO-secreting tumor(renal cell carcinoma, pheochromocytoma).
-Srikar Sama
For Diagnosing the specific cause of polycythemia follow these 3 steps:
STEP1: First check for RBC mass
1)Elevation of Hgb and/or Hct due to a decrease in plasma volume alone (ie, without an increase of the RBC mass) is referred to as relative polycythemia.
2)An increase of RBC mass refers to Absolute polycythemia. It can be categorized as either primary or secondary polycythemia.
STEP2: To diagnose the causes of absolute polycythemia. Check for EPO levels
1)Primary polycythemia is caused by a mutation in RBC progenitor cells that results in increased RBC mass. So there is a decrease in EPO levels. Ex: polycythemia vera (PV)
2)Secondary polycythemia refers to an increase of RBC mass caused by elevated serum EPO. Most often, this is due to an appropriate physiologic response to tissue hypoxia, or by autonomous EPO production(eg, an EPO-secreting tumor)
STEP3: To diagnose the causes of secondary polycythemia. Check PaO2 and SaO2 levels
1)If PaO2<65% and SaO2<92% then it is because of chronic hypoxia due to high altitude, COPD, Smoking, etc.
2)If PaO2 and SaO2 levels are normal then consider EPO-secreting tumor(renal cell carcinoma, pheochromocytoma).
-Srikar Sama
Wow excellent work Dr.srikar
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