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': 'Which of the following is associated with a sudden decrease in serum calcium levels? \nSelect and explain. \nA. Skeletal manifestations, B. Increase in phosphate levels, C. Increased thyroxine and PTH secretion, D. Increase in excitability of muscle and nerve', 'role': 'user'}, {'content': 'Answer: D \nExplanation: Manifestations of acute hypocalcemia includes increased neuromuscular excitability and cardiovascular effects of a decrease in ionized calcium. Nerves exposed to low ionized calcium, levels shows decreased threshold for excitation, repetitive responses to a single stimulus and in extreme cases continuous activity. Increased neuromuscular excitability manifest as paresthesias and tetany. In severe cases laryngeal spasm, seizures and death can occur. Ref: Poh Pathophysiology: Concepts of Altered Health States By Ruth A. Hannon, Page 762', 'role': 'assistant'}]