Ageing and Metabolic Bone Conditions

Question 1

How would osteoporosis appear on a blood test?

Answer 1

Normal calcium, normal phosphates, normal alkaline phosphatase, normal PTH, normal 1,25 vitamin D

ALL NORMAL VALUES

Question 2

How would osteomalacia appear on a blood test?

Answer 2

Reduced calcium, phosphates and 1,25 dihydroxyvitamin D and increased PTH and alkaline phosphatase

Question 3

How would Paget’s disease appear on a blood test?

Answer 3

Normal calcium, phosphates, PTH and vitamin D but VERY HIGH levels of alkaline phosphatase

Question 4

How would renal failure appear on a blood test?

Answer 4

Reduced calcium and vitamin D with increased phosphates, alkaline phosphatase (or normal) and PTH.

Question 5

How would primary hyperparathyroidism appear on a blood test?

Answer 5

Normal vitamin D, normal/increased alkaline phosphatase, increased PTH and calcium with decreased phosphates.

Question 6

From what age do we begin to lose bone mass?

Answer 6

30

Question 7

What is a T score in relation to bone mineral density?

Answer 7

A comparison against a 30 year old’s bone density matched for the same sex and ethnicity

Question 8

What is a Z score in relation to bone mineral density?

Answer 8

A comparison against a normal individual’s bone density matched for age, sex and ethnicity

Question 9

What is a normal bone mineral density?

Answer 9

> -1 SD from mean (T score)

Question 10

What values indicate osteopenia on DEXA scans?

Answer 10

Between -1 to -2.5 SD from mean (T score)

Question 11

What values indicate osteoporosis on a DEXA scan?

Answer 11

Less than -2.5 SD from mean (T score)

Question 12

What type of bone is most susceptible to osteoporosis?

Answer 12

Trabecular bone as it has a higher turnover rate and a larger surface area

Question 13

Which bones are most susceptible to osteoporosis?

Answer 13

Vertebral bodies, femoral neck and wrist

Question 14

How may osteoporosis be treated conservatively?

Answer 14

With calcium and vitamin D supplements and more weight-bearing exercise

Question 15

What treatments are used in osteoporosis?

Answer 15

HRT, SERMs (raloxifine), bisphosphonates, teriparatide and denosumab

Question 16

How may osteoporosis be treated with HRT?

Answer 16

This is the first choice in premature menopause for women as oestrogen inhibits osteoclasts

Question 17

How may osteoporosis be treated with raloxifene?

Answer 17

This is a selective oestrogen receptor modulator which may be used to prevent osteoporosis in post-menopausal women

Question 18

How may osteoporosis be treated with bisphosphonates?

Answer 18

Directly inhibits osteoclasts by acting on enzyme in them which work to breakdown bone

Question 19

How may osteoporosis be treated with teriparitide?

Answer 19

This is a PTH analogue which works to activate osteoblasts more than osteoclasts when given in particular doses

Question 20

How may osteoporosis be treated with denosumab?

Answer 20

Monoclonal antibody which binds to RANKL to prevent it from activating osteoclast differentiation (by RANK receptor activation)

Question 21

What are the potential complications of bisphosphonate use?

Answer 21

Can lead to giant osteoclasts, osteonecrosis of the jaw and atypical fractures (subtrochanteric and femoral shaft – and old osteocytes signal for remodelling but there are fewer good osteoclasts to facilitate this)

Question 22

What is osteomalacia?

Answer 22

Where there is insufficient calcium and phosphate to mineralise new osteoid –> bones soften

Question 23

What is the most common cause of osteomalacia?

Answer 23

Vitamin D deficiency

Question 24

How does disease severity differ between osteomalacia and rickets?

Answer 24

Rickets is the form of osteomalacia that occurs in children, and therefore the epiphyseal growth plate is still open which means that more long-term deformity can result from the condition

Question 25

What are the most important lab results seen to diagnose osteomalacia?

Answer 25

Low serum calcium and phosphate with a high alkaline phosphatase

Question 26

What are the dietary sources of calcium?

Answer 26

Milk, bread, beans, plies, dried fruit and green leafy vegetables

Question 27

What is Paget’s disease?

Answer 27

The excessive breakdown and formation of bone, followed by disorganized bone remodelling

Question 28

What are the three phases of Paget’s disease?

Answer 28

Increased rate of bone resorption - large numbers of giant osteoclasts
Compensatory phase - accelerated deposition of bone in disorganised manner (woven bone)
Burnt out phase - hyper-cellularity of bone diminishes leading to Pagetic bone with hyper-vascular bone marrow

Question 29

Which bones are most commonly affected by Paget’s disease?

Answer 29

Pelvis, femur, skull, vertebra and tibia.

Question 30

Which cancer may occur as a result of Paget’s disease?

Answer 30

Osteosarcoma - there are giant cells and is one of the most malignant of cancers, metastasising rapidly to the lungs

Question 31

Where does osteosarcoma often metastasise to?

Answer 31

Lungs

Question 32

How is Paget’s disease treated?

Answer 32

Bisphosphonates, calcium and vitamin D supplements, pain management and surgery

Question 33

How does the ‘burnt out phase’ of Paget’s disease appear histologically?

Answer 33

There is irregular, thickened trabecular bone with prominent cement lines with bone marrow replaced by fibre-vascular connective tissue

Question 34

How do you diagnose osteosarcoma from a histological specimen?

Answer 34

Giant cells confirm the diagnosis of osteosarcoma arising out of Paget’s disease

Question 35

What is sclerotosis (Van Buchem syndrome)?

Answer 35

An autosomal recessive disorder where there is absent or reduced production of sclerostin (usually inhibits osteoblasts). Therefore results in endosteal hyperostosis –> fracture resistance and excessive height

Question 36

What is sclerostin?

Answer 36

Compound secreted by osteocytes to inhibit osteoblasts

Question 37

What is the mode of inheritance of Van Buchem syndrome (sclerotosis)?

Answer 37

Autosomal recessive disorder

Question 38

What is the consequence of Van Buchem syndrome?

Answer 38

Endosteal hyperostosis –> fracture resistance and excessive height