1 - Biochemical Disorders of Bone

Question 1

What is osteoporosis?

Answer 1

A quantitative defect of bone characterised by reduced bone mineral density and increased porosity

Question 2

According to WHO, what bone mineral density is classified as…

• Osteopenia (intermediate stage)
• Osteoporosis

Answer 2

Osteopenia: 1-2.5 standard deviations below mean peak value

Osteoporosis: >2.5 standard deviations below mean peak value

Question 3

What are the two types of primary osteoporosis?

Answer 3

Type 1: Post-menopausal osteoporosis

Type 2: Osteoporosis of old age

Question 4

What are the causes of secondary osteoporosis?

Answer 4

• Corticosteroid use
• Alcohol abuse
• Malnutrition
• Chronic disease
• Endocrine disorders

Question 5

How is osteoporosis diagnosed?

Answer 5

DEXA scanning to measure bone mineral density

Question 6

Although osteoporosis cannot be treated, what treatments can be used to slow progression?

Answer 6

• Exercise + good diet + sun exposure
• Calcium and vitamin D supplements
• Bisphosphonates
• Desunomab

Question 7

Which intervention has shown the greatest efficacy for osteoporosis?

Answer 7

Bisphosphonates

Question 8

In osteoporosis, serum bone chemistry is normal/abnormal

Answer 8

Normal

Question 9

What is osteomalacia?

Answer 9

A qualitative defect of bone characterised by abnormal softening of the bone due to deficient osteoid mineralization

Question 10

What is Rickett’s?

Answer 10

Osteomalacia in children resulting in deformities of the growing skeleton

Question 11

What are the principal causes of osteomalacia?

Answer 11

• Calcium deficiency
• Vitamin D deficiency
• Phosphate deficiency

Question 12

What may cause these deficiencies that lead to osteomalacia?

Answer 12

Malnutrition
Malabsorption
Lack of sunlight
Hypophosphataemia
Chronic kidney disease

Question 13

Describe the following parameters of serum bone biochemistry in osteomalacia…

• Calcium
• Serum phosphate
• Serum alkaline phosphatase

Answer 13

• Calcium: low
• Serum phosphate: low
• Serum alkaline phosphatase: high

Question 14

How is osteomalacia treated?

Answer 14

Vitamin D therapy

Calcium and phosphate supplementation

Question 15

What does hyperparathyroidism involve?

Answer 15

Overactivity of the parathyroid glands with high levels of parathyroid hormone (PTH)

Question 16

What are the causes of...
- Primary
- Secondary
- Tertiary
... hyperparathyroidism?

Answer 16

• Primary: benign adenoma, hyperplasia, malignant neoplasm
• Secondary: physiological overproduction of PTH secondary to hypocalcaemia
• Tertiary: chronic secondary hyperparathyroidism which will not improve with biochemical correction

Question 17

What does overproduction of PTH cause?

Answer 17

Hypercalcaemia

Question 18

What are the symptoms of hypercalcaemia?

Answer 18

fatigue, depression, bone pain, myalgia, nausea, thirst, osteoporosis

Question 19

What 2 lytic lesions can be caused by hyperparathyroidism?

Answer 19

• Brown tumours

- Osteitis fibrosa cystica

Question 20

What is renal dystrophy?

Answer 20

The typical bone changes seen in chronic kidney disease

These include osteomalacia, sclerosis of bone and calcification of soft tissues

Question 21

What is Paget’s disease?

Answer 21

A chronic bone disorder resulting in thickened, brittle and mis-shapen bones

Question 22

Which bones are commonly affected by Paget’s disease?

Answer 22

Pelvis
Femur
Skull
Tibia

Question 22

Which bones are commonly affected by Paget’s disease?

Answer 22

Pelvis
Femur
Skull
Tibia

Question 22

Which bones are commonly affected by Paget’s disease?

Answer 22

Pelvis
Femur
Skull
Tibia

Question 22

Which bones are commonly affected by Paget’s disease?

Answer 22

Pelvis
Femur
Skull
Tibia