<s>[INST] context: The clinical presentation of primary hyperparathyroidism is described on page 769. Parathyroid bone disease is now rare due to earlier diagnosis and treatment. Osteitis fibrosa results from increased bone resorption by osteoclasts with fibrous replacement in the lacunae. This may present as bone pain and tenderness, fracture and deformity. Chondrocalcinosis can occur due to deposition of calcium pyrophosphate crystals within aicular cailage. It typically affects the menisci at the knees and can result in secondary degenerative ahritis or predispose to attacks of acute pseudogout Skeletal X-rays are usually normal in mild primary hyperparathyroidism, but in patients with advanced disease characteristic changes are observed. In the early stages there is demineralisation, with subperiosteal erosions and terminal resorption in the phalanges. A 'pepper-pot' appearance may be seen on lateral X-rays of the skull. Reduced bone mineral density, resulting in either osteopenia or osteoporosis, is now the most common skeletal manifestation of hyperparathyroidism. This is usually not evident radiographically and requires assessment by DEXA (p. 1065). Primary hyperparathyroidism Primary hyperparathyroidism is caused by autonomous secretion of PTH, usually by a single parathyroid adenoma, which can vary in diameter from a few millimetres to several centimetres. It should be distinguished from secondary hyperparathyroidism, in which there is a physiological increase in PTH secretion to compensate for prolonged hypocalcaemia (such as in vitamin D deficiency, p. 1126), and from teiary hyperparathyroidism, in which continuous stimulation of the parathyroids over a prolonged period of time results in adenoma formation and autonomous PTH secretion (Box 20.39). This is most commonly seen in individuals with advanced chronic kidney disease (p. 483). The prevalence of primary hyperparathyroidism is about 1 in 800 and it is 2-3 times more common in women than men; 90% of patients are over 50 years of age. It also occurs in the familial MEN syndromes (p. 795), in which case hyperplasia or multiple adenomas of all four parathyroid glands are more likely than a solitary adenoma. Clinical and radiological features The clinical presentation of primary hyperparathyroidism is described on page 769. Parathyroid bone disease is now rare due to earlier diagnosis and treatment. Osteitis fibrosa results from increased bone resorption by osteoclasts with fibrous replacement in the lacunae. This may present as bone pain and tenderness, fracture and deformity. Chondrocalcinosis can occur due to deposition of calcium pyrophosphate crystals within aicular cailage. It typically affects the menisci at the knees and can result in secondary degenerative ahritis or predispose to attacks of acute pseudogout In nephrocalcinosis, scattered opacities may be visible within the renal outline. There may be soft tissue calcif ication in aerial walls and hands and in the cornea. DAVIDSONS PRINCIPLES AND PRACTICE OF MEDICINE 22ND EDITION PAGE NO-769 [/INST] question: Osteitis fibrosa cystica is seen in | options: A: Hyperparathyroidism B: Hypoparathyroidism C: Hypothroidism D: Hypehyroidism | answer: A </s>