Differentiate Primary from secondary polycythemia

Explanation:

There are a few criteria that a patient must fulfil in order to be classified as Primary polycythemia (2out of 3).

1. O2 saturation greater than 92%
2. Splenomegaly
3. High cell counts for other cell lines too like platelets or leukocytes.

Also the erythropoietin levels in primary polycythemia are low to normal but in secondary polycythemia the increased cell count is mediated thru erythropoietin - the levels of which are raised.

The NAP (Neutrophil alkaline phosphatase- also called LAP for leukocyte AP) levels are raised in primary polycythemia but not in secondary.