5 - Ageing and Metabolic Bone Conditions

Question 1

What percent of bone mass is usually lost in a year from the age of 40+?

Answer 1

0.7% a year

Question 2

After menopause, what is the percentage of bone mass loss in women?

Answer 2

2-9% a year

Question 3

What is a T score

Answer 3

number of standard deviations from the mean young (30 yr) same gender and ethnicity

Question 4

What is the Z score

Answer 4

number of standard deviations from mean aged, same gender and ethnicity

Question 5

What is osteopenia

Answer 5

A precursor to osteoporosis

Question 6

Where do you usually measure for osteoporosis

Answer 6

Neck of femur

Vertebral bodies

Question 7

What does the DEXA scan measure

Answer 7

Bone density

Question 8

Osteopenia T score

Answer 8

-1 to -2.4

Question 9

Osteoporosis T score

Answer 9

below -2.5

Question 10

What does DEXA stand for

Answer 10

Dual Energy X-ray Absorptiometry

Question 11

Prevalence of osteoporosis

Answer 11

2% at 50 years

Greater than 25% at 80 years

Question 12

What bones are more susceptible to osteoporotic bone loss

Answer 12

Neck of femur
Vertebral bodies
High proportion of trabecular bone

Question 13

What treatments are given for osteoporosis?

Answer 13

Calcium supplements
Vitamin D supplements
HRT
Selective oestrogen receptor modulator
Biphosphonates 
Denosumab
Teriparatide

Question 14

What is the minimum time HRT is given for

Answer 14

5 years

Question 15

Example of a Selective Oestrogen Receptor Modulator

Answer 15

Raloxifene

Question 16

What is the MoA of biphosphonates

Answer 16

Inhibitors of bone reabsorption
Inhibit osteoclast activity
Promote osteoclast apoptosis
Increase OPG production
Decrease RANKL expression

Question 17

Complications of biphosphonates

Answer 17

Giant osteoclasts
Osteoncrosis of the jaw
Atypical fractures

Question 18

What is teriparatide

Answer 18

A recombinant PTH

Will activate osteoblasts without activating osteoclasts

Question 19

What is Denosumab + how often does it need to be given

Answer 19

Monoclonal antibody which binds to RANKL and prevents it’s signalling
therefore inhibits the formation of osteoclasts

Needs to be given every 6 months via subcutaneous injection

Question 20

What is osteomalacia

Answer 20

Insufficient calcium and phosphate to mineralise bone osteoid
The bones are softer and more liable to bend or fracture

Question 21

Cause of osteomalacia

Answer 21

Lack of vitamin D

Question 22

What is rickets and why is it more deforming

Answer 22

Childhood osteomalacia

More deforming as in children the epiphyseal growth plate is open

Question 23

What would lab results show in osteomalacia

Answer 23

Low serum calcium and phosphorus

High alkaline phosphatase

Question 24

Why is alkaline phosphatase high in osteomalacia

Answer 24

Due to high osteoblast activity

Question 25

What would an X-ray look like in someone with osteomalacia

Answer 25

Pseudofractures = unmineralised sections of bone | Areas of unmineralised bone

Question 26

What is the normal level of unmineralised osteoid?

Answer 26

<20%

Question 27

What colour is unmineralised and mineralised osteoid on biopsy

Answer 27

Orange - unmineralised (up to 100% in osteomalacia) | Green - mineralised

Question 28

How do you treat osteomalacia

Answer 28

Vitamin D supplements Increase calcium in diet Sun or UV exposure

Question 29

Calcium containing foods

Answer 29

Milk Bread Beans Green leafy vegetables

Question 30

What is Pagets disease also called

Answer 30

Osteitis Deformans

Question 31

Percentage population with pagets

Answer 31

3% >50 y/o

Question 32

What are the 3 stages of Pagets disease

Answer 32

1) Increased rate of bone resorption (large no of giant osteoclasts) 2) Compensatory phase (Increased bone formation as woven bone, accelerated deposition in a disorganised manner) 3) Burn out phase (Sclerotic) - Bone hypercellularity may deminish leaving dense pagetic bone Hypervascular bone marrow Irregular thickened trabeculae Bone marrow replaced by fibrovascular CT

Question 33

Which bones are most commonly affected in osteomalacia?

Answer 33

``` Pelvis Femur Vertebrae Skull Tibia ```

Question 34

What is osteosarcoma?

Answer 34

A rare complication of pagets disease where a cancer forms

Question 35

Where are osteosarcomas usually

Answer 35

Long bone | Near the knee

Question 36

How do you treat osteosarcoma

Answer 36

Remove part of the bone | Limb amputation

Question 37

How do you treat osteomalacia

Answer 37

Biphosphates Calcium and vitamin D supplements Pain management Surgery

Question 38

How long does an osteomalacia patient have to take biphosphates

Answer 38

Oral - 2-6 months | IV single infusion to 3 infusions

Question 39

What is sclerostosis also known as

Answer 39

Aka van buchem syndrome

Question 40

Genetics of sclerostosis

Answer 40

Autosomal recessive

Question 41

Features of sclerostosis

Answer 41

Endosteal hyperostosis Resistance to fracture Excessive height

Question 42

Pathophysiology of sclerostosis

Answer 42

Absence or reduced production of sclerostin | therefore osteoblasts are not inhibited