Metabolic bone conditions

Question 1

Which 5 factors measured in a blood test differentiate between metabolic bone conditions?

Answer 1

1. Ca
2. PO4
3. Alkaline phosphtase
4. PTH
5. active form vit D3 =1,25(OH)2 vit D

Question 2

what is osteoporosis?

Answer 2

loss of bone mass - bone reabsorption > formation

Question 3

what age does bone mass loss occur?

Answer 3

> 40 yrs loss 0.7% bone mass per year

Question 4

In females what event speeds up bone loss and why?

Answer 4

MENOPAUSE (increases bone loss 2-9% per year) - loss of oestrogen - omj increase bone reabsorption + decreases Ca absorption from gut

Question 5

Why is osteoporosis less common in men?

Answer 5

Men have

1. more MUSCLE- more stress on skeleton - increases bone mass
2. more TESTOSTERONE - anabolic steroid - increases muscle + bone mass

THEREFORE MEN HAVE MORE BONE TO BEGIN WITH THAN WOMEN

Question 6

What age does bone mineral density peak?

Answer 6

25-27yrs

Question 7

What is the peak bone mass in both males and females?

Answer 7

males = 1500g

females =1000g

Question 8

What does bone mass measure?

Answer 8

the total mass of claicum in the skeleton in grams

Question 9

How is bone mineral density measured?

Answer 9

T or Z score

Question 10

What is a T score?

Answer 10

no. of SD from young (30yr) + same sex + ethnicity

Question 11

What is a Z score?

Answer 11

no of SD from old+ same sex + ethnicity

Question 12

Which is more commonly used + why?

Answer 12

T score - more data been measured for this

Question 13

What equipment is used to measure T/Z score?

Answer 13

DEX scan

Question 14

Interpretation of T score for normal/osteopenia/osteoporosis

Answer 14

• normal = +/- 1 SD

- osteopenia = -1 2.5 SD

Question 15

What type of bone is most suspectible to osteoporosis and why?

Answer 15

trabecular bone -

1. greater S.A of sketelon
2. finer collagen framework
3. in areas suspectible to stress

Question 16

What 2 areas of the body are commonly affected in osteoporosis + why?

Answer 16

vertebral bodies + femur neck - high proportion of trabeculae bone

Question 17

What are the 2 changes visible in osteoporotic bone?

Answer 17

1. thinner cortices
   2.thinner trabeculae
   HOWEVER NORMAL OSTEOID - bone matrix :mineral not affected

Question 18

What is the 1st stage of osteoporosis treatment?

Answer 18

non pharmacological treatment

1. Ca supplement = 1500mg/day
2. Vitamin D = 800 IU/day
3. exercise >30 mins,3 times a week =increase muscle mass - increase bone mass

Question 19

What is the 1st stage of osteoporosis treatement in menopauasal women?

Answer 19

HRT for at least 5 years

Question 20

What is raloxifene?

Answer 20

SERM - selective oestrogen receptor modulator - only affects oestrogen receptor in bone NOT uterus + breast - avoids uterine + breast cancer from overproduction of oestrogen

Question 21

Which pharmological treatment is most popular for osteoporosis?

Answer 21

Bisphosphonates -ending = ‘ate’ - alendronate + resdronate

Question 22

Why is the bisphosphonate ETIDRONATE only used as a last resort treatment option?

Answer 22

reduces osteoclast activity BUT ALSO bone calcification - osteomalacia

Question 23

Action of bisphosphonates

Answer 23

reduces osteoclastic activity- prevents bone resorption- stronger bone
reduces risk of fracture by 50%

Question 24

Complication of bisphosphonates

Answer 24

osteonecrosis of jaw + atypical fractures

Question 25

2 future treatments for osteoporosis

Answer 25

TERIPARATIDE - intermittent exposure to PTH- act. osteoblasts>osteoclasts
DENOSUMAB - subcutaneous injection , twice a year - inhibits osteoclasts

Question 26

What deficiency causes osteomalacia (rickets)?

Answer 26

vitamin D + calcium deficiency

Question 27

What is the consequence of vit D on bone?

Answer 27

• insufficient Ca + PO4 to mineralise new bone osteoid

- bone becomes softer- bend/fracture

Question 28

Why is rickets more severe in children?

Answer 28

-epiphyseal growth plates are still open - more deforming - BOW LEGS

Question 29

Presentation of rickets in adults

Answer 29

• psuedofractures

- areas of unmineralised bone at locations of high bone turnover

Question 30

In normal bone how much of the osteoid is unmineralised?

Answer 30

<20%

Question 31

What feature would be seen in a bone autopsy for osteomalacia?

Answer 31

high % of UNmineralised osteoid (up in 100% in severe cases)

Question 32

Treatment for osteomalacia

Answer 32

AIM = treat vit D + calcium deficiency

• vit D supplements
• increase dietary Ca intake
• increase sun /U exposure (sunbed)

Question 33

What is another name for Paget’s disease?

Answer 33

osteitis deformans

Question 34

Describe the process bone resorption

Answer 34

osteoclasts break down bone - release minerals to blood (eg Ca)

Question 35

3 stages of Paget’s

Answer 35

1 INCREASED RATE OF BONE RESORPTION (hyperactive osteoclasts)

2. compensatory phase -increase bone formation (hyperactive osteoblast- fill lacunae created by osteoclast overactivity - deposition woven bone in disorganised manner)
3. BURNT OUT PHASE - both osteoclasts+ osteoblasts worn out - leaves DENSE Pagetic bone

Question 36

Key presentation of Paget’s

Answer 36

UNILATERAL - see changes in skull + femur + tibia

Rare 50yrs + 10% pop >80yrs)

Question 37

What is a rare complication of Paget’s?

Answer 37

OSTEOSARCOMA

• most common in young
• most malignant cancer
• spreads RAPIDLY (to lungs)
• in long bone (knee)
• prevention = LIMB AMPUTATION

Question 38

Treatment for Paget’s

Answer 38

3 options:

1. bisphosphonates
2. Calcium + vit D supplements
3. Calcitonin