Biochemical disorders of bone Flashcards Preview

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Flashcards in Biochemical disorders of bone Deck (41):
1

What is osteoporosis?

A quantitative defect of bone characterised by reduced bone mineral density and increased porosity i.e. the bone is of normal quality, there is just not enough of it

2

What is the risk associated with osteoporosis?

Increased risk of fracture with little or no trauma

3

What is the definition of osteoporosis on bone mineral density scan?

Less than 2.5 standard deviations below the mean peak value of young adults of same race and sex

4

What is osteopenia?

An intermediate stage where bone mineral density is between 1 to 2.5 standard deviations below mean peak value

5

What is type 1 osteoporosis?

Post‐Menopausal Osteoporosis with an exacerbated loss of bone in the post‐menopausal period

6

What increases risk & severity of type 1 osteoporosis?

Early menopause
White/Caucasian
Lack of exercise
Smoking
Alcohol abuse
Poor diet

7

What is type 2 osteoporosis?

Osteoporosis of old age with a greater decline in bone mineral density than expected

8

What fractures are particularly likely with type 1 osteoporosis?

Colles fractures
Vertebral insufficiency fractures

9

What increases risk & severity of type 2 osteoporosis?

White/Caucasian
Lack of exercise
Smoking
Alcohol abuse
Poor diet
Lack of vitamin D/sun exposure
Chronic disease

10

Which fractures are particularly associated with type 2 osteoporosis?

Vertebral fractures
Femoral neck fractures

11

What conditions can osteoporosis occur secondary to?

Corticosteroid use
Alcohol abuse
Malnutrition
Chronic disease e.g. CKD, malignancy, rheumatoid arthritis
Endocrine disorders e.g. Cushing's, hyperthyroidism, hyperparathyroidism

12

What happens to the levels of serum calcium and phosphate in osteoporosis?

They remain the same

13

What pharmacological treatments can be used to try and prevent further fragility in osteoporosis?

Calcium & vitamin D supplements
Bisphosphonates
Desunomab
Strontium

14

What are the names of some bisphosphonates and how do they help in osteoporosis?

Alendronate, risedronate, etidronate
Reduce osteoclastic resorption

15

What is desunomab?

A monoclonal antibody which reduces osteoclast activity

16

How does strontium help in osteoporosis?

Increases osteoblast replication and reduces resorption

17

What is osteomalacia?

A qualitative defect of bone with abnormal softening of the bone due to deficient mineralization of osteoid (immature bone) secondary to inadequate amounts of calcium and phosphorus

18

What is Ricket's?

Osteomalacia in children: abnormal softening of bone due to inadequate amounts of calcium and phosphorus, resulting in deformity of the growing skeleton

19

What are the main causes of osteomalacia and rickets?

Insufficient calcium absorption from the intestine because of lack of dietary calcium or a deficiency of or resistance to the action of vitamin D
Phosphate deficiency caused by increased renal losses

20

What are some of the more specific causes of osteomalacia and ricket's?

Malnutrition (Ca & vit D)
Malabsorption (low vit D absorption)
Lack of sunlight exposure
Hypophosphateamia (re‐feeding syndrome, alcohol abuse – impairs phosphate absorption, malabsorption, renal tubular acidosis)
Long term anticonvulsant use
Chronic kidney disease (reduced phosphate resorption & failure of activation vitamin D)

21

What are some of the presenting complaints of osteomalacia & rickets?

Bone pain in femur, pelvis or spine
Bone deformity (particularly in rickets)
Fractures easily
Symptoms of hypocalcaemia

22

What are some of the symptoms of hypocalcaemia?

Paraesthesiae
Muscle cramps
Irritability
Fatigue
Seizures
Brittle nails

23

What serum bone biochemistry abnormalities can be seen in osteomalacia?

Low calcium
Low serum phosphate
High serum alkaline phosphatase

24

What is the treatment for osteomalacia and rickets?

Vitamin D and calcium supplements

25

What is hyperparathyroidism?

Overactivity of the parathyroid glands with high levels of parathyroid hormone

26

What are the causes of primary hyperparathyroidism?

Benign adenoma
Hyperplasia
Malignant neoplasia

27

What does high levels of hyperparathyroid hormone result in?

Hypercalcaemia

28

What are some of the symptoms of hypercalcaemia?

Fatigue
Depression
Bone pain
Myalgia
Nausea
Thirst
Polyuria
Renal stones
Osteoporosis

29

What does biochemistry show in hyperparathyroidism?

High levels of PTH
High levels of calcium
Phosphate normal or low

30

What are the causes of secondary hyperparathyroidism?

Secondary to hypocalcaemia:
Vitamin D deficiency
CKD

31

What is tertiary hyperparathyroidism?

A condition seen in patients with chronic secondary hyperparathyroidism (usually CKD) who develop an adenoma which will continue to produce PTH despite biochemical correction

32

What are some of the complications of hyperparathyroidism?

Fragility fractures
Lytic lesions in bone known as Brown tumours or osteitis fibrosa cystica which may need skeletal stabilisation

33

What is the treatment for hyperparathyroidism?

Removal of adenomatous gland
Treatment of underlying cause e.g. vitamin D supplementation

34

How is high levels of serum calcium treated?

As an emergency:
Iv fluid
Bisphosphonates
Calcitonin

35

What is Paget's disease?

A chronic disorder which results in thickened, brittle and misshapen bones

36

What is the pathological process in Paget's disease?

Increased osteoclast activity results in abnormally increased bone turnover
Osteoblasts try to correct this, forming new bone but failing to remodel the bone sufficiently
This results in increased thickness of bone with low density

37

How might Paget's disease present?

Asymptomatic
Incidental finding on Xray
Arthritis
Pathologic fractures
Deformity
Pain
High output cardiac failure (due to increased blood flow through pagetic bone

38

Which bones are commonly affected by Paget's disease?

Pelvis
Femur
Skill
Tibia
Ear ossicles

39

What are the radiographic features of Pagets disease

Enlarged bone
Thickened cortices
Coarse, thickened trabeculae
Mixed areas of lysis and sclerosis

40

What does biochemistry blood tests show in Paget's disease?

Serum alk. phos. raised
Calcium normal
Phosphorus normal

41

How is Paget's disease treated?

Bisphosphonates
Calcitonin if extensive lytic disease