This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Endocrinology, Subject name: Physiology
[{'content': 'Which of the following cause low serum calcium? \nSelect and explain. \nA. Vit D deficiency, B. Parathyroid, C. GH, D. Glucocoicoids', 'role': 'user'}, {'content': 'Answer: A \nExplanation: Vitamin D is a group of fat-soluble secosteroids responsible for enhancing intestinal absorption of calcium and phosphate. Calcitriol circulates as a hormone in the blood, regulating the concentration of calcium and phosphate in the bloodstream and promoting the healthy growth and remodeling of boneRef: Ganong&;s review of medical physiology; 24th edition; page no:-379', 'role': 'assistant'}]