Disorders of Bone

Question 1

What characterises osteoporosis?

Answer 1

Low bone mass and micro-architectural destruction, producing an increased risk of fracture.

Question 2

What is the role of osteoclasts?

Answer 2

Bone resorption

Question 3

What is the role of osteoblasts?

Answer 3

Bone formation

Question 4

What factors influence bone mass density?

Answer 4

Weight
Sex hormones
Diet
Exercise levels

Question 5

What are the most common sites for an osteoporotic bone fracture?

Answer 5

Neck of femur
Distal radius
Vertebral body
Humeral neck

Question 6

What is an example of a fracture common in young people?

Answer 6

Colles’ fracture (caused by FOOSH)

Question 7

What is an example of a fracture common in the elderly?

Answer 7

Vertebral fracture (often with minimal trauma)

Question 8

What is a potential complication of a vertebral fracture?

Answer 8

Thoracic kyphosis - this will result in height loss.

Question 9

What is osteopenia?

Answer 9

A bone mineral density that is > 1 and <2.5 standard deviations below the young adult mean.

Question 10

What is osteoporosis?

Answer 10

A bone mineral density that is >2.5 standard deviations below the young adult average.

Question 11

In which patients is a DEXA scan indicated?

Answer 11

Those over 50, with a low-trauma fracture/deemed to be high-risk.

Question 12

What are causes of secondary osteoporosis?

Answer 12

Cushing’s disease
Coeliac disease
COPD
CKD

Question 13

What lifestyle changes can improve outcomes for those with osteoporosis?

Answer 13

High-intensity strength training
Low-impact weight-bearing exercise
Avoidance of smoking/alcohol excess
Falls prevention
Increased calcium intake

Question 14

What pharmacological management options exist for osteoporosis?

Answer 14

HRT
Selective oestrogen modulators
Testosterone replacement (for young men)
Bisphosphonates

Question 15

What is the first-line therapy in osteoporosis?

Answer 15

Bisphosphonates

Question 16

If bisphosphonates are contraindicated, what can be given?

Answer 16

Zoledronic acid
Denosumab

Question 17

What is a rare complication of Paget’s disease?

Answer 17

Osteosarcoma

Question 18

What genetic bone condition also causes blue sclera?

Answer 18

Osteogenesis imperfecta

It is a disorder of type 1 collagen, and follows an autosomal dominant inheritance pattern.

Question 19

What should always be considered as a potential cause of repeated fractures during childhood?

Answer 19

Non-accidental injury

Question 20

What is calcium metabolism dependent on?

Answer 20

Vitamin D

Question 21

What symptoms are associated with hypercalcaemia?

Answer 21

Bone pain
Kidney stones
Abdominal pain
Psychological disturbances

Question 22

What are the 2 most common causes of hypercalcaemia?

Answer 22

Primary hyperparathyroidism
Malignancy

Question 23

How may primary hyperparathyroidism present?

Answer 23

Raised serum calcium
Raised/Normal serum PTH
Raised urinary calcium

Question 24

Why can malignancy cause hypercalcaemia?

Answer 24

Metastatic bone destruction
Release of PTH-related peptide from a solid tumor

Question 25

How is hypercalcaemia treated?

Answer 25

Give 4-6L of 0.9% saline, within 24 hours. May also give a loop diuretic/bisphosphonates (will lower calcium levels in a few days).

Question 26

What type of scan can be performed to locate a parathyroid adenoma?

Answer 26

Sestamibi scan

Question 27

When is a parathyroidectomy performed?

Answer 27

End organ damage (e.g. osteoporosis, or gastric ulcer) Very high calcium levels Those under 50 eGFR <60ml/min

Question 28

What is primary hyperparathyroidism?

Answer 28

A primary overactivity of the parathyroid gland, caused by high calcium, and high PTH levels.

Question 29

What is secondary hyperparathyroidism?

Answer 29

A physiological response to low calcium/vitamin D levels (causing high PTH).

Question 30

What is tertiary hyperparathyroidism?

Answer 30

When the parathyroid gland becomes autonomous due to years of overactivity (causes very high levels of PTH and calcium).

Question 31

What condition is almost always seen in those with a MEN1/MEN2 syndrome?

Answer 31

Parathyroid adenoma

Question 32

What is familial hypocalciuric hypercalcaemia (FHH)?

Answer 32

A condition where serum calcium levels are high, although levels within the urine are low. It is the result of calcium-sensing receptors becoming insensitive, leading to continuously high PTH levels. Usually this is asymptomatic, and will follow an autosomal dominant pattern of inheritance.

Question 33

What are symptoms of hypocalcaemia?

Answer 33

Paraesthesia Muscle cramps/tetany Muscle weakness Fits Bronchospasm Chovstek's sign Prolonged QT

Question 34

How is acute hypocalcaemia treated?

Answer 34

Give IV calcium gluconate, 10ml 10% over 10 mins - this will prevent cardiac/respiratory arrest.

Question 35

What are causes of hyperparathyroidism?

Answer 35

Congenital abnormalities (e.g. DiGeorge Syndrome) Destruction Autoimmune disease Hypomagnesemia Iron overload Idiopathic

Question 36

What are causes of hypomagnesemia?

Answer 36

Alcohol Thiazide-like diuretics PPIs GI upset Pancreatitis Malabsorption

Question 37

Why does hypomagnesemia cause low serum calcium?

Answer 37

As magnesium is required to release calcium from the intracellular compartment.

Question 38

How does pseudohypoparathyroidism present?

Answer 38

Low calcium Raised PTH Due to the development of PTH resistance (a genetic defect of GNAS1).

Question 39

How does pseudo-pseudohypoparathyroidism present?

Answer 39

Normal calcium levels Patient will only have symptoms of pseudohypoparathyroidism - no deranged bloods to match clinical picture.

Question 40

What symptoms are associated with pseudohypoparathyroidism?

Answer 40

Bone abnormalities Obesity Subcutaneous calcification Learning difficulties Brachdactyly

Question 41

What is vitamin D deficiency known as in children?

Answer 41

Rickett's

Question 42

What is vitamin D deficiency known as in adults?

Answer 42

Osteomalacia

Question 43

How does osteomalacia present?

Answer 43

Low calcium Muscle wasting Dental defects Tender bones

Question 44

How can chronic renal disease cause vitamin D deficiency?

Answer 44

As 1-hydroxylase enzymes will not be able to carry out their function.