• Osteoporosis

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Definition:

Osteoporosis literally means porous bone. According to NIH definition osteoporosis a skeletal disorder characterized by compromised bone strength predisposing a person to an increased risk of fracture. It is common, silent, measurable, treatable and potentially lethal disease.

osteoporosis
osteoporosis

A Major Health Threat

  • In the US 34 million individuals have low bone mass and 10 million have osteoporosis.
  • Up to 50% of postmenopausal women will suffer an osteoporotic-related fracture within their lifetime. 30% of all women reaching 90 years of age will suffer a hip fracture.
  • 25% of men over age 50 will develop related fractures in their lifetime.

Classification

Primary

Type 1: Postmenopausal (six times more common in women)

Type 2: Involutional or senile osteoporosis (twice as common in women)

Idiopathic osteoporosis: Occurs in children and young adults of both sexes with normal gonadal function.

Secondary

  • Endocrine disorders:
    • Estrogen Deficiency
    • Testosterone Deficiency
    • Cushing’s Syndrome (Hypercortisolism)
    • Hyperparathyroidism
    • Hyperthyroidism
  • Gastrointestinal/Nutritional Disorders
    • Vitamin D Deficiency
    • Anorexia Nervosa
    • Celiac Disease
    • Malabsorption
    • Primary Biliary Cirrhosis (PBC)
    • Inflammatory Bowel Disease (IBD)
  • Chronic Drug Therapy
    • Anticonvulsants
    • Glucocorticoids
  • Genetic Disorders
    • Osteogenesis Imperfecta
  • Other Conditions
    • Immobilization
    • Post-transplantation
    • Hematologic Marrow Infiltration (e.g. Lymphoma, Multiple Myeloma)
    • Connective Tissue Disease (e.g. Rheumatoid Arthritis, Systemic Lupus Erythematosus)
osteoporosis
osteoporosis

Risk Factors

  • Highest risk
    • Caucasian or Asian
    • Female
    • Thin or Petite
    • Elderly
  • Increased Risk
    • Cigarette Smoking
    • Alcohol Abuse
    • Positive Family History
    • Sedentary lifestyle
    • Low Dietary Calcium Intake

Clinical Features

  • Osteoporosis usually starts silently and may not be uncovered until a bone fractures.
  • Osteoporosis usually causes pain when complicated by fracture.
  • First presentation is often a fracture (Colles, femoral neck and vertebra)
  • Vertebral collapse is the hallmark of osteoporosis which can lead to height shrinkage
osteoporosis
osteoporosis

Investigations

  • Densitometry: High standard quality
  • Plain Radiography
    • Limited value
    • Osteoporosis is not detectable until more than 40% of bone lost.
  • 25-hydroxy vitamin D: Most useful test
  • Plasma calcium, phosphate, alkaline phosphatase: Usually normal
  • Thyroid stimulating hormone.
  • Rule out of multiple myeloma in osteoporotic area.

Bone Mass Densitometry (BMD) is recommended for

  • All women ≥ 65 and men ≥ 70, regardless of risk factors
  • Younger postmenopausal women and men 50- 70 with concern based on clinical risk factor profile
  • Adults who have a fracture after age 50
  • Adults taking a medication (e.g. steroids) or with a condition (e.g. rheumatoid arthritis) associated with bone loss
  • Men with testosterone deficiency
  • Anyone being treated for osteoporosis to monitor therapy

National Osteoporosis Foundation, 2013

Interpretation of BMD

Dual energy X-ray absorptiometry (DEXA):

Current gold standard for the diagnosis of osteoporosis. It assesses

  • whole-body mass (lumbar spine)
  • Regional bone mass (head of femur).

Bone Mass Densitometry (BMD)

  • T score: The number of standard deviations (SD) away from the mean BMD of a 30-year-old adult
    • Normal: ≥ -1
    • Osteopenia: -1 to -2.5
    • Osteoporosis: ≤ -2.5
    • Severe Osteoporosis: < -2.5 with Pathological Fractures
  • Z score: The number of SDs away from the age- and sex-matched mean BMD.
    • Used to express bone density in patients <50 years, children, premenopausal women, and younger men.
    • Low (< - 2): Indicates investigation for underlying causes of a bone deficit.

Prevention and Treatment

Nonpharmacologic

  • Adequate Nutrition: keep BMI >18
  • Lifestyle Factors: Stop smoking. Limit alcohol and caffeine intake.
  • Hip protectors: In High risk patients. Adherence is poor.
  • Adequate Dietary Intake of Calcium

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  • Vitamin D/Sunlight

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  • Exercise

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  • Fall Prevention 

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Pharmacotherapy

  • Antiresorptive Agents
    • Estrogen Replacement Therapy (ERT/HRT)
    • Selective Estrogen Receptors Modulators (SERMs)
      • Raloxifene
    • Bisphosphonates
      • Alendronate
      • Risedronate
      • Ibandronate
      • Zoledronic Acid
    • Denosumab
  • Anabolic (Bone-Building) Agent
    • Teriparatide (Parathyroid Hormone)
  • Newer Therapies
    • New Antiresorptive Agents
      • Osteoprotegerin
      • Cathepsin K inhibitor- Odanacatib
      • New SERM’ s
    • New Anabolic Agents:
      • Anti-Sclerostin Antibody
      • Romosozumab
      • Blosozumab
    • New forms of PTH

Treatment Monitoring

  • 2 years after therapy begins
  • 1–2 years after therapy changes significantly (More frequently in patients with higher risk of bone loss)

Recent Studies Show

  • Romosozumab maybe be preferable to Alendronate (Details)
  • Children and adolescents who exercise regularly will face lower risk of osteoporosis in elderly. (Details)
  • Nutrition may be superior to exercise in osteoporosis prevention (Details)
  • Consumption of too much vitamin A may harms bones (Details)