Osteoporosis

Question 1

Definition

Answer 1

Systemic skeletal disorder characterised by low bone mass and micro archhitectural deterioration of bone tissue, with a consequent increase in bone fragility and susceptibility to fracture

Question 2

Epidemiology

Answer 2

Disease of the elderly

Can affect middle aged people

Postmenopausal women

Primary disorder or secondary disorder (20% women is secondary and 40% male cases)

Question 3

Causes (Aetiology)

Answer 3

Primary:
– occurs naturally as a person ages
– as people age, bone mass is lost much quicker than it is made, causing osteoporosis

Secondary:
– hyperthyroidism
– Gastrointestinal- malabsorption, partial gastrectomy, liver disease
– Rheumatological- RA
– Malignancy- multiple myeloma, metastatic CA
– Drugs- corticosteroids, heparin, thyroxine, cytotoxic drugs

Question 4

Factors increase bone loss

Answer 4

• family history
• obesity (sedentary lifestyle)
• female
• early and post menopause
• endocrine disease
• drugs
• alcohol
• diet
• oophorectomy (removal of ovaries)
• protein intake
• smoking
• caffeine

Question 5

factors decreasing bone loss

Answer 5

• calcium
• dietary lifestyle
• increase exercise

Question 6

Clinical features

Answer 6

• can be asymptomatic
• loss of height, trunk shrinkage
• a bone that breaks much easier than expected

Question 7

Investigations

Answer 7

Blood biochemistry

Radiographic changes (X-ray)

Bone density measurements:
– energy x-ray absorptiometry
– quantitative CT
– quantitative ultrasound measurements
– bone biopsy
– biochemical markers of bone turnover

Bone density has to be at least 2.5 standard deviations less than the average to be classed as osteoporosis

Question 8

Treatment

Answer 8

General advice:
– exercise
– dietary change
– calcium/vitamin D
– moderate alcohol and caffeine intake

Drug therapy:
– bisphosphonates (most common)
—- can cause apoptosis of osteoclasts
– SERMS- Raloxifene
– Calcitonin
– PTH

Preventing falls:
– avoidance of drugs in elderly (may cause falls)
– walking aids
– hip protectors

Question 9

Pathophysiology

Answer 9

Bone remodelling:
– in younger ages, osteoblasts are at a higher function than osteoclasts, meaning we grow and bone formation happens
– as we get older, osteoclasts become more active, meaning there’s a drop in bone mass
– peak bone age 20-29
– 0.7% bone mass loss per year on average

Increasing osteoblast activity:
– Oestrogen and testosterone being higher in younger ages, increases the activity of osteoblasts, which is why we grow when we are younger
– physical activity also increases the activity of osteoblasts

Increasing age on osteoporosis:
– increase age=decrease osteoblast activity (senile osteoporosis)
– decreased oestrogen during menopause=decreased osteoclast activity and increase osteoclast activity (postmenopausal osteoporosis)
—- up to 40% of women will have some sort of osteoporosis

– decrease in physical activity as you age=decrease in osteoblast activity
– corticosteroids increase activity of osteoblasts- leading to increased bone resorption

This all leads to decreased bone formation and increased bone resorption:
– meaning there is a decrease in bone mass:
—- thinning of compact bone
—- more holes within the spongy bone
—- meaning bone is more liable to fracture

Most common fracture location:
– vertebrae (MC)
– neck of femur
– Wrist
– Ribs