This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Haematology, Subject name: Anatomy
[{'content': 'In polycythemia vera,all are raised except \nSelect and explain. \nA. Hematocrit, B. Platelet count, C. RBC, D. Erythropoietin', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Ref Robbins 9/e 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', 'role': 'assistant'}]