Osteoporosis causes, risk, pathogenesis, types, diagnosis, prevention, treatment

This is a discussion of Osteoporosis regarding its definition, aetiology, types, pathogenesis, risk factors, clinical picture (symptoms and signs), diagnostic investigations, methods of prevention and treatment approach .

What is meant by Osteoporosis ?

• It is defined as a decrease in the absolute amount of bone mass leading to enhanced bone fragility with increased risk of pathological fractures.
• Unlike osteomalacia, the defect in osteoporosis is that the bone that is present is normally mineralized but is deficient in quantity, quality and structural integrity.

How Osteoporosis develops ? Pathogenesis

• Bone mass increases rapidly up to the age of puberty and rises slightly more in the twenties and thirties and then begins to decline around age of 40 years.
• In males there is a gradual decline but females show an accelerated loss in the 10 years following the menopause.
• Osteoporosis occurs as the end result of many years mismatch between the rate of bone resorption and bone formation .

Risk factors 

• Female, Family history, early menopause.
• Decreased Ca intake, reduced activity, smoking, alcohol, AI antacid, excessive caffeine, corticosteroids therapy and genetic factors.

Causes and types of osteoporosis

• TypeI  :  -Post menopausal osteoporosis.
• Type II : -Senile osteoporosis.
• Secondery osteoporosis: 2ry to the following disorders :
- Cushing's syndrome. . - Hyperthyroidism.
- Acromegally, D.M. - Rheumotoid disease.
- Chronic renal failure - Chronic liver disease.
- Rheumatoid arthritis. - Immobilization.
- Drugs e.g corticosteroids.

How to diagnose Osteoporosis ?

Clinical picture of Osteoporosis
• Bony aches, back pain, Pathological fractures
• Loss of height due to thoracic kyphosis and collapsed vertebrae.
- The most common sites of pathological fractures are the forearm (colles fracture), spine (vertebral fracture) and femur (hip fracture).

Investigations to diagnose osteoporosis

• Plasma chemistry is normal (normal serum ca, P and alkaline P).
Alkaline phosphatase may be increased following a recent fracture.
X ray :  Decreased bone density (rarefaction or osteopenia).
DEXA scan to measure bone density by dual-energy x ray absorption scanning (DEXA), it may show osteopenia (low bone mass), osteoporosis or severe osteoporosis.
• Investigations of the cause e.g serum creatinine, blood urea, thyroid function tests, cortisol level.

How to prevent osteoporosis

Prevention of osteoporosis
• Exercise.
• Calcium supplements 1000-1500 mg/day, also diary products are recommended e.g Milk, cheese and Yogurt.
• Restriction of caffeine intake.
• Stop smoking and alcohol intake.
• Estrogen replacement therapy in early menopause.

Treatment of Osteoporosis

• Bisphosphonates, they are osteoclast antagonist e.g Alendronate 10 mg/day (osteomax or fosamax) orally at morning, it can be given 70 mg one dose/week. Bisphosphonates should be used with caution in
patient with renal impairment.
Alendronate causes oesophageal ulceration , So to minimize that side effect, The patient may take the tablets on an empty stomach before breakfast (poorly absorbed) with a full glass of water and remains upright for 30 minutes . 
• Calcitonin 100 I.U every' other day by S.C or IM injection. It can be given by nasal spray 200u/day.
• Calcium 1000- 1500 mg/d orally.
• Vitamin 0 400-800 IU/d orally, altacalcidol (vit 0 analogue) can be used.
• Estrogen therapy.

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