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Dynamic Bone formation


Disease of bone structure

Bone becomes more porous -> inc risk of fractures

Bone formation


Half-life of 7 years

Bits eaten away while new bits replace them

  • Osteoclasts
    • break down protein and release calcium
  • Osteoblasts
    • attracted to area being broken down
    • secrete collagen
    • deposit calcium and phosphate onto collagen

Why important

Significant mortality and morbidity

High cost to the community

Investigations simple and non-invasive

Treatments effective and safe


1 in 2 women, 1 in 4 men, will suffer osteoporotic fracture

Costs Australia $1.7 billion annually in direct costs

$7 billion indirectly

Under diagnosed

>75% men, >90% women who should be investigated & treated are not

Under treated

>75% those affected are not treated

Effective treatment reduce subsequent fractures by 50%


25% >50yo die in the year following hip fracture

25% >50yo need nursing home care after hip fracture

Hip fracture most common reason for admission to nursing home

Aging and falls

Sensory and balance deterioration

Muscular-skeletal changes


Behaviour and psychological changes

Bone Mineral Density

Measured in standard deviations from the norm

-2.5 std dev below normal for young white female = osteoporosis

= 5x risk of fracture

Better than cholesterol or hypertension at predicting disease

Affected by genetics, age

The cascade effect

Women with a spinal fracture 4x as likely to have another in the next year

Risk factors for OP



Family history

Low calcium

Low Vit D



Thin or small frame


Body maintains serum [Ca] over bone, so blood tests not helpful

Why more women

Lower peak bone mass, smaller frame

Oestrogen drops off at menopause; bones lose calcium at a much faster rate than before