Biochemical Disorders of Bone Flashcards
What is the most significant difference in investigation findings between osteoporosis and osteomalacia?
Osteoporosis - normal calcium and phosphate levels
Osteomalacia - low calcium and phosphate levels
What condition presents with Looser’s Zones (psuedofractures) on XR?
Osteomalacia
What is osteomalacia known as when it presents in children?
What is the most notable presentation of this condition?
Rickett’s
Bow shaped legs
What causes osteomalacia?
Abnormal softening of bone due to insufficient mineralisation of osteoid - secondary to low levels of calcium and phosphate
Poor calcium levels - can be due to low levels of vit D = poor absorption
What is osteoporosis?
What defines it?
Decreased bone density and increased pores
Bone density of less than 2.5 standard deviations below the mean
What are the 2 types of osteoporosis?
Type 1 = post-menopausal (oestrogen is protective against osteoporosis)
Type 2 = old age
What condition is sustained corticosteroid use associated with?
Osteoporosis
What is first line treatment for osteoporosis?
What is their MoA?
What is their common side effect?
Bisphosphates - alendronate
Reduce osteoclast activity
Reflux and oesophageal erosions
How is osteoporosis diagnosed?
DEXA bone scan
What condition can cause hypercalcaemia as a result of increased bone breakdown leading to bone pain?
Hyperparathyroidism - increased levels of PTH (parathyroid hormone)
What is Paget’s disease?
What causes the bone to be weak?
An abnormality in bone turnover
-> sclerotic weakened bone due to mosaic pattern of rebuilding bone (more porous and less stable structure)
Paget’s disease is most commonly asymptomatic but when it does present how may it appear?
Thickened bone in axial skeleton (larger hats)
Warm skin to touch (increased metabolism of bone)
What is osteopenia?
An intermediate stage before osteoporosis
1-2.5 standard deviations below the mean
What bones are most likely to be affected by Paget’s disease?
- Skull
- Spine
- Pelvis
What biochemistry would be different in Paget’s disease?
Raised ALP
How is Paget’s disease managed (be specific with drug names)?
Bisphosphonates (if raised ALP) - PAMIDRONATE/ALIDRONATE
NSAIDS/other analgesias
Long term use of corticosteroids is a strong risk factor for osteoporosis. If they were to fracture a bone what would be seen on XR?
Exuberant callus formation
corticosteroid induced osteoporosis
What is the common side effect of biphosphates?
Oesphagitis - similar process of taking them to doxycycline
Can also cause osteonecrosis of the jaw - much rarer though
A reduction in bone marrow density on Xray is seen in what condition?
Osteoporosis
What is the name for the rare condition in which there is a defect in osteoclast function.
What does this result in?
Osteopetrosis
Hard and dense bone which is prone to fracture
