osteoporosis

Question 1

osteoprogenitor cells

Answer 1

stem cell population, gives rise to osteoblasts

Question 2

osteoblasts

Answer 2

responsible for bone formation, cover the surface of the bone

Question 3

osteocytes

Answer 3

,tire bone cells, embedded in lacunae, relatively inactive. maintain the bone matrix through cell to cell communication and influence bone remodelling. mechanosensing

Question 4

osteoclasts

Answer 4

multinucleate, derived from haematopoietic cells. In response to mechanical stresses and physiological demands they reabsorb the bone matrix by demineralisation

Question 5

molecular signs of osteoporosis

Answer 5

• degreased size of osteons
• thinning of trabecular
• enlargement of Haversian and marrow spaces

Question 6

risk factors of osteoporosis

Answer 6

genetic/biologial sex 
lifestyle/nutritional 
medical conditions 
drugs 
previous fragility fracture

Question 7

lifestyle and nutritional risk factors

Answer 7

smoking
excess alcohol
sedentary
prolonged immobilisation

Question 8

drugs which can increase the likelyhood of osteoporosis

Answer 8

excessive thyroid therapy
anticoagulants
anticonvulsants
chemotherapy

Question 9

what are the two classifications of osteoporosis

Answer 9

1. post menopausal
   - affects mainly cancellous bone
   - vertebral and distal radius fracture is common
   - related to loss of oestrogen
   - F:M 6:1
2. Age related on those over 75
   - affects cancellous and cortical bone
   - is related to poor calcium absorption
   - hip and pelvic fractures common
   - F:M 2:1

Question 10

Disuse osteoporosis

Answer 10

Conditions resulting in prolonged immobilisation, typically in neurological or muscle disease

Question 11

clinical consequences of osteoporosis

Answer 11

increase in bone fragility susceptibility to fracture: micro- or fragility fracture

Question 12

fragility fracture

Answer 12

low energy trauma

mechanical forces that would not ordinarily cause fracture

Question 13

common sites of osteoporotic fractures

Answer 13

distal radius 
neck of femur 
vertebral body 
spine 
proximal humorous

Question 14

investigations for osteoporosis

Answer 14

blood tests:
- FBC
- Serum Biochemistry 
- Bone profile 
Thyroid function tests 
Testosterone and gonadotrophin levels in men 
X-ray of lumbar and thoracic spine 
- more than 30% bone loss 
Bone mineral density measurement

Question 15

scans

Answer 15

duel-energy X-ray absorptiometry scan DEXA
low-dose X-rays with two distinct energy peaks (one absorbed by soft tissue and the other by bone)
subtracting one from the other gives a patients bone mineral density

Question 16

T score

Answer 16

comparison with a young adult of the same gender with peak bone mass
> -1. normal
-1 to -2.5 osteopenia

Question 17

z score

Answer 17

comparison of the patients BMD with data from the same age/sex/size

Question 18

treatment of osteoporosis

Answer 18

• biphophonates
  • e.g. alendronate, risedronate
  • disrupt the activity of osteoclasts
  • potential side effects – oesophagitis, mandibular necrosis
• anabolic agents, intermittent PTH
• Ca ++ supplements
• Hormone replacement therapy, however carriers increased risk of breast cancer
• increase exercise