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: Medicine
[{'content': 'The most common manifestation of osteoporosis is: \nSelect and explain. \nA. Compression fracture of the spine, B. Asymptomatic, detected incidentally by low serum Calcium, C. Bowing of legs, D. Loss of weight', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Answer is A (Compression fracture of the spine) : It most commonly presents as backache of varying degrees of severity. This backache is due to spontaneous fracture or collapse of veebra. Osteoporosis is defined as a reduction of bone mass or density, sufficient to increase the risk offracture. Osteoporosis is usually asymptomatic until fracture occurs (but serum Calcium is normal Q). Serum parathyroid hormone, 25-(OH) D2, Calcium, Phosphorus and Alkaline phosphatase are usually normal.', 'role': 'assistant'}]