Osteoporosis

Question 0

What are the frequent fractures associated with osteoporosis?

Answer 0

• Colles fracture (distal radius)
• Neck of femur (hip fracture)
• Vertebrae (trapped nerves —> pain)
• Ribs

Question 1

What are the risk factors for osteoporosis?

Answer 1

• Increased age
• Caucasian/Asian
• Female (reduced oestrogen in menopause)
• Reduced calcium/Vit. D in diet
• Hypogonadism (reduced testosterone/oestrogen)
• long-term steroid treatment (e.g. ASTHMA)
• Immobility
• Hyperparathyroidism (increased bone breakdown)

Question 2

What are the components of the extra-cellular matrix in bone?

Answer 2

Type 1 Collagen (intra-H bonds & covalent cross-links provide tensile strength)

Glycoproteins (aid mineralisation)

Calcium hydroxyapatite crystals (calcium phosphate)

Question 3

What is the effect of PTH on bone remodelling?

Answer 3

Stimulates osteoclasts

Therefore increases bone resorption

Question 4

Outline the steps in bone remodelling.

Answer 4

RESTING STAGE = periosteum present

RESORPTION = osteoclasts break down calcium hydroxyapatite crystals

REVERSAL = macrophages …….

FORMATION = osteoblasts secrete matrix

MINERALISATION = osteoblasts secrete minerals?…..

Question 5

What is the difference between osteoblasts and osteocytes?

Answer 5

Osteoblasts = secrete matrix and facilitate mineralisation during bone remodelling

Osteocytes = osteoblasts embedded in bone (maintenance of bone)

Question 6

What is the reference point for bone mineral density disorders?

Answer 6

Mean young healthy white woman

Question 7

How is bone mineral density measured?

Answer 7

Dual Energy X-ray Absorptiometry (DEXA)

Question 8

What is the difference between a diagnosis of osteopenia and osteoporosis?

Answer 8

Osteopenia = bone mineral density 1-2.5 stan. dev.s away from the mean young healthy white woman

Osteoporosis = bone mineral density 2.5< stan. dev.s away from the mean young healthy white woman

Question 9

What are some other conditions which affect bone mineral density?

Answer 9

• Rickets/osteomalacia (reduced Vit. D intake —> reduced mineralisation)
• Paget’s disease (abnormally large/active osteoclasts —> woven bone)
• Malabsorption disorders e.g. Crohn’s, coeliac disease (reduced calcium/Vit. D absorption)

Question 10

What are the three classes of oestrogens?

Answer 10

• Estrone
• Estradiol
• Estriol

Question 11

What is the difference between pathological and non-pathological fractures?

Answer 11

Non-pathological fractures = fracture caused by huge forced applied to normal bone (small force will not break bone)

Pathological fractures = fracture caused by little force applied to weakened bone

Question 12

What is the prevention for osteoporosis?

Answer 12

Increase dietary intake of calcium and Vit. D

Hormone replacement therapy (but not for menopause; only for hypogonadism)

Question 13

What is the progression-limiting treatment for osteoporosis?

Answer 13

Maintain dietary intake of calcium and Vit. D

Weight-bearing exercises

Limit falls

Increase mobility

Stop smoking/reduce drinking

Bisphosphonates (bind to calcium hydroxyapatite crystals and reduce activity of osteoclasts)

(or strontium ranelate, as bisphosphonates can cause oesophagitis)