This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Physiology
[{'content': 'A 32-year-old high altitude mountaineer is observed to have a hematocrit of 70 percent. Which of the following represents the most likely cause/explanation \nSelect and explain. \nA. Polycythemia with increased red cell mass, B. Relative Polycythemia due to dehydration, C. Polycythemia due to hemoconcentration, D. Polycythemia with high altitude pulmonary edema', 'role': 'user'}, {'content': 'Answer: A \nExplanation: At high altitude, there can be acute changes and changes due to acclimatization.\nAcute mountain sickness\n\nDyspnoea, dizziness, tiredness, tachycardia, palpitation, nausea, vomiting etc. \nAt higher altitudes- pulmonary oedema and cerebral oedema may occur. \n\nAcclimatization changes\n\nHyperventilation leading to respiratory alkalosis \nIncreased 2,3DPG- Hb-O2 dissociation curve shifts to right. \nIncreased erythropoietin leading to absolute polycythemia with increased red cell mass. \nIncreased renal excretion of bicarbonate \nIncreased tissue vascularity \nIncreased oxidative metabolism \nIncreased diffusion capacity of the lung\u200b\nIncreased myoglobin', 'role': 'assistant'}]