<prompt> Not a marker for hyperparathyroidism is :Increase in serum calciumIncrease in 24 hour urinary calcium excretionDecrease in serum calcitoninSubperiosteal resorption of phalanges  <response>: 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 