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': 'Not a marker for hyperparathyroidism is : \nSelect and explain. \nA. Increase in serum calcium, B. Increase in 24 hour urinary calcium excretion, C. Decrease in serum calcitonin, D. Subperiosteal resorption of phalanges', 'role': 'user'}, {'content': "Answer: C \nExplanation: Answer is C (Decrease in serum calcitonin) : Serum calcitonin is no marker fir hyperparathyroidism. It antagonizes the actions of parathyroid hormone and may be used as a modality of treatment of hypercalcemia secondary to hyperparathyroidism. Markers of hyperparathyroidism (|ed PTH): 1. Increased serum calcium: Stimulates Vit D which causes increased absorption of Ca-H- from gut Increased calcium reabsorption from tubules Increases osteoblastic activity in bones and mobilizes calcium from bone into serum. 2. Decreased serum phosphorus: - PTH acts on tubules to increase excretion of phosphorus. 3. Increased 24 hr urine calcium: - Despite increased reabsorption of Ca++ in renal tubules urinary calcium is increased owing to increased filtration of calcium in glomerular filtrate. 4. Increased Alkaline phosphatase: -Increased resorption of bone leads to compensatory elevation of osteoblastic activity 5. Radiological changes: Subperiosteal resorption of phalanges is characteristic (hand X Rays are always advised) Bone resorption i.e. osteitis fibrosa et cystica (brown tumours) `Salt pepper' or 'pepper pot skull' appearance - Loss of lamina dura", 'role': 'assistant'}]