<prompt> A 40-year-old female presents with multiple lytic bone lesions, fracture clavicle and periosteal resorption of 2nd and 3rd metatarsals. What is the most likely diagnosis?HyperthyroidismHyperparathyroidismRenal osteodystrophyOsteomalacia  <response>: Ans. b. Hyperparathyroidism Ref: Schwartz 9e p1377-1380; Sabiston 19e p928-932; Bailey 26e 771-774 25e p800- 804: Harrison 19e 2470-2474, 18e p3100-3105The most likely diagnosis in a 40-year-old female presenting with multiple lytic bone lesions, fracture clavicle and periosteal resorption of 2nd and 3rd metatarsals is hyperparathyroidism.The distinctive bone manifestation of hyperparathyroidism is osteitis fibrosa cystica. X-ray changes include resorption of the phalangeal tufts and replacement of the usually sharp cortical outline of the bone in the digits by an irregular outline subperiosteal resorption. In recent years, osteitis fibrosa cystica is very rare in primary hyperparathyroidism, probably due to the earlier detection of the disease. - Harrison 18e p3102Primary HyperparathyroidismPHPT arises from increased PTH productionQ from abnormal parathyroid glands and results from a disturbance of normal feedback control exerted by serum calcium.More common in womenQSolitary adenomaQ is the MC cause in 80Parathyroid adenomas are most commonly located in inferior parathyroid glandsQ.Increased PTH production leads to hypercalcemia via:Increased GI absorption of calciumIncreased production of vitamin D3Reduced renal calcium clearanceEtiology:Exposure to Low-dose therapeutic ionizing radiation and familial predispositionRenal leak of calciumDeclining renal function with ageAlteration in the sensitivity of parathyroid glands to suppression by calciumLithium therapyGenetics:Most cases of PHPT are sporadicAlso associated with MEN-1, MEN-2A. isolated familial HPT, and familial HPT with jaw-tumor syndromeClinical Features:Patients with PHPT formerly presented with the classic pentad of symptoms: Kidney stonesQ Painful bonesQ Abdominal groansQ Psychic moansQ Fatigue overtonesQAlteration in the typical patient with PHPT due to widespread use of automated blood analyzers.Patients are more likely to be minimally symptomatic or asymptomatic.Currently, most patients present with weakness, fatigue, polydipsia, polyuria, nocturia, bone and joint pain. constipationQ, decreased appetite, nausea, heartburn, pruritus, depression, and memory loss.Renal calculi are typically composed of calcium phosphate or oxalateQOsteitis fibrosa cystica in advanced PHPTPathognomonic radiologic findings on X-rays of hands, characterized by:Subperiosteal resorptionQ most apparent on the radial aspectQ of middle phalanxQ of 2nd and 3rd fingersBone cystsQTufting of distal phalangesQDiagnosis:Elevated serum calcium and intact PTH or two-site PTH levels, without hypocalciuria establishes the diagnosis of PHPT with virtual certaintyQDecreased serum phosphate 50 and elevated 24-hour urinary calcium 60 in PHPTQLocalization:99mTc-labeled sestamibi: Most widely used and accurate modalityQ sensitivity 80 for detection of parathyroid adenomasTreatment:Parathyroidectomy for patients having classic symptoms of PHPT or 50 yearsQSERM and bisphosphonates are used to lower serum calcium and increase BMD in PHPT.Indications for Parathyroidectomy in Asymptomatic Primary HPT Serum calcium 1 mgdL above the upper limits of normal Life-threatening hypercatcemic episode Creatinine clearance reduced by 30 Kidney stones on abdominal x-rays Markedly elevated 24-h urinary calcium excretion 400 mgd Substantially decreased bone mineral density at the lumbar spine, hip, or distal radius Age 50 years Long-term medical surveillance not desired or possible 