<prompt> In polycythemia vera,all are raised exceptHematocritPlatelet countRBCErythropoietin  <response>: Ref Robbins 9e p656 relative: Reduced plasma volume hemoconcentration Absolute primary Abnormal proliferation of myeloid stem cells, normal or low erythropoietin levels polycythemia vera; inherited activating mutations in the erythropoietin receptor rare secondary Increased erythropoietin levels Adaptive: lung disease, high-altitude living, cyanotic hea disease Paraneoplastic: erythropoietin-secreting tumors e.g., renal cell carcinoma, hepatomacellular carcinoma, cerebellar hemangioblastoma Surreptitious: endurance athletes 