MedLecturesMadeEasy's video: Metabolic Bone Disorders

This is a short video on five bone diseases caused by altered bone metabolism. I created this presentation with Google Slides. Image were created or taken from Wikimedia Commons I created this video with the YouTube Video Editor. ADDITIONAL TAGS: Metabolic bone disorders Bone diseases caused by disturbed bone metabolism Osteitis fibrosa cystica Paget’s disease of bone Osteogenesis imperfecta Osteomalacia / rickets Osteoporosis Osteitis fibrosa cystica AKA brown tumor of hyperparathyroidism Excessive bone resorption (mediated by osteoclast activity) Hyperparathyroidism → increased PTH → resorp bone Pathology → diminished bone strength Subperiosteal (below connective tissue) resorption Bone cysts Radiology: cyst formation, mimics bone neoplasms Histology: fibrous tissue, hemorrhage (hemosiderin pigment) Treatment: underlying cause of hyperparathyroidism Osteitis fibrosa cystica Paget’s disease of bone Excess bone resorption and formation Repetition and acceleration of cyclic osteon breakdown and rebuilding Results in disorganized bone (“jigsaw puzzle”, “mosaic”) Epi: prevalence increases with age Pathology: larger, weaker, less dense, more vascular bones Affects axial skeleton and proximal long bones Clinical: isolated AP increase Symptoms: usually asymptomatic, but some get bone pain/fracture/deformity, arthritis, neuro complications (compression) Radiology: cotton wool spots (sclerosis, whiter areas); Nuc: increased uptake in affected bones Treatment: bisphosphonates (antiresorptive) Osteogenesis imperfecta AKA brittle bone disease or Lobstein syndrome Inadequate bone formation with defective bone matrices Due to mutation in bone collagen gene (8 variants) Clinical: unexpected fractures, family hx, blue sclera Diagnose with DNA tests or collagen analysis Treatment: bisphosphonates, surgery; no cure Inadequate bone formation with defective bone matrix mineralization Due to insufficient calcium or phosphorus Most frequently caused by vitamin D deficiency Also caused by chronic kidney disease → kidney converts inactive to active vit D 25-OH-D → 1,25-OH2-D Pathology: softening of bone Adults (osteomalacia)→ bone pain, muscle weakness, fracture risk Children (rickets) → bone deformities (ie bowing), dental issues Treatment: restore vitamin D levels (or active form (calcitriol)), calcium and phosphorus if necessary Osteoporosis Reduced bone matrix and mineralization secondary to various factors No single etiology → 50% hereditary, 50% acquired (diet, age, exercise, comorbidities) Epi: most common metabolic bone disorder Pathology: increased fragility, fractures Decrease in bone density (2.5 std dev) Osteopenia is milder form (1 to 2.5 std dev) Bone mineral density (BMD) measured with dual-energy X-ray absorptiometry (DEXA) scan T-score is std dev multiple difference from avg ethnicity/gender-matched 30 yo Z-score is std dev multiple difference from avg ethnicity/gender/age-matched pt Primary osteoporosis Inherent risks: fracture hx, female, white, age, genetics, fam hx Modifiable risks: smoking, alcohol, low estrogen, low Ca, sedentary, low BMI Secondary osteoporosis → due to other diseases, surgeries, medications Hormones: corticosteroids (net resorption); thyroid/growth hormone (net formation) Dzs: Cushing’s; hyper-parathyroid/thyroid/prolactin; hypo-gonad/pituitary; gastric bypass and other malabsorption; Ehlers-Danlos; OI; myeloma, lymphoma/leukemia Drugs: ethanol, glucocorticoids, heparin Clinical: kyphosis (hump-back), scoliosis (S-spine), height loss, gait/balance issues Radiology: x-ray only detects 30-50% loss → DEXA preferred Treatment: Ca, vit D, estrogen replacement; calcitonin; selective estrogen receptor modulators (SERMs, ie raloxifene and tamoxifen), bisphosphonates, denosumab (RANK Ab); teriparatide (PTH analog, anabolic) Osteitis fibrosa cystica Paget’s disease of bone Osteogenesis imperfecta Osteomalacia / rickets Osteoporosis