Pathology - Osteoporosis

Pathology - Osteoporosis:
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I. Definition & Epidemiology:

Definition: Osteoporosis is a metabolic bone disease characterized by decreased bone mass, increased bone fragility, and a heightened risk of fractures. It's a silent disease often undetected until a fracture occurs.
Epidemiology: Extremely common, predominantly affecting elderly women, although it can occur in all ages.

II. Etiology (Causes):

Primary Cause: Estrogen deficiency (particularly post-menopause in women) is a major risk factor.
Other Contributing Factors:
- Glucocorticoid therapy (steroids)
- Cushing's syndrome
- Hyperparathyroidism
- Hyperthyroidism
- Celiac disease
- Inflammatory bowel disease

III. Pathogenesis (Disease Mechanisms):

Bone Mass Determination: Bone mass in later life is influenced by:
- Peak bone mass: Achieved during early adulthood (largely genetic, but modifiable by nutrition, physical activity, and early life health).
- Rate of bone loss: Increases with age due to:
  - Decreased bone turnover
  - Reduced physical activity
  - Diminished calcium absorption (gut)
  - Accelerated bone loss in women post-menopause (due to estrogen deficiency).
Glucocorticoid Effect: Glucocorticoids negatively impact bone health by:
- Decreasing osteoblast activity and lifespan
- Reducing gut calcium absorption
- Increasing renal calcium loss
- Suppressing sex hormone production (further increasing bone loss).

IV. Presentation (Clinical Features):

Often Asymptomatic: Most cases remain undiagnosed until a fracture occurs.
Fracture Sites: Common fracture locations include:
- Vertebrae (leading to height loss and kyphosis – curvature of the spine) – can occur spontaneously or with minimal trauma.
- Distal radius (Colles' fracture) – typically from a fall.
- Neck of femur (hip fracture) – often from a fall from standing height or less.

V. Histopathology (Microscopic Appearance):

Cancellous Bone (spongy bone): Thinning and disconnection of trabeculae (supporting bone structures).
Cortical Bone (compact bone): Thinning with enlargement of Haversian canals (channels containing blood vessels).

VI. Prognosis:

Hip Fractures (Neck of Femur): Pose the most significant risk, often requiring hospitalization and surgery. Mortality risk is increased in elderly patients with other health problems.

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