19- OSTEOPOROSIS

• Osteoporosis


  A progressive systemic skeletal disease characterized by reduced bone mass, micro-architectural deterioration of bone tissue, and increased skeletal fragility, resulting in decreased bone strength and increased risk of fracture
• Normal bone remodeling process


  1. Activation phase: osteoclasts recruited to the surface of the bone

  2. Resorption phase: osteoclasts generate an acidic microenvironment between the cell and the surface of the bone, dissolving the mineral content of the bone

  3. Reversal phase: osteoclasts undergo apoptosis and osteoblasts are recruited to the bone surface

  4. Formation phase: osteoblasts then deposit collagen; this is mineralized to form new bone
• Risk factors for osteoporosis


  • BMD-dependent: Female sex/hypogonadism, Increasing age, Caucasian/Asian, Previous fragility fracture, family history of hip fracture
  • BMD-independent: Immobilization, Low BMI, Chronic liver/renal disease, COPD, Smoking and alcohol, GI disease, low dietary calcium intake, vitamin D deficiency, Steroid therapy, Endocrine (Cushing's, hyperthyroidism, hyperparathyroidism), Increased risk of falls, Drugs (heparin, anticonvulsant, cyclosporin), High bone turnover, Others (diabetes, multiple myeloma), Rheumatoid arthritis
• Fragility fractures


  • Typically occur at 4 sites: Thoracic vertebrae (may lead to kyphosis and loss of height), Lumbar vertebrae, Proximal femur, Distal radius (Colles fracture)
• Diagnosis of osteoporosis


  Clinically by presence of fragility fracture, BMD measured by DEXA (gold standard in measurement of bone density) of the lumbar spine and proximal femur
• WHO diagnostic guidelines


  1. score + 2.5 to -1.0 is normal, T score between -1.0 and -2.5 is osteopenia, T-score -2.5 or below is osteoporosis
• Lifestyle measures for osteoporosis


  • Adequate calcium (700-1000 mg daily, 1500 mg post-menopause), Adequate vitamin D (400-800 international units daily), Protein (1g/kg/day), Exercise (30 minutes three times per week), Smoking cessation, Fall prevention, Avoidance of heavy alcohol use, Avoidance of drugs that increase bone loss, ex: glucocorticoids (if possible)
• Pharmacological interventions for osteoporosis


  • Oral bisphosphonates (alendronate and risedronate) as first-line therapy, IV bisphosphonates if oral is not tolerated or contraindicated, Denosumab (human monoclonal antibody to RANKL), Selective estrogen receptor modulators (SERM) such as Raloxifene, Teriparatide (recombinant parathyroid hormone), Estrogen therapy (HRT) for early post-menopausal women with perimenopausal symptoms
• Osteoporosis prevention measures


  • Adequate calcium and vitamin D, Smoking & alcohol cessation, HRT usually not indicated unless the women is already taking it for other reasons, If the patient has osteopenia + fracture risk factors, she can be started on bisphosphonates or Raloxifene to reduce her risk