osteomalacia + rickets Flashcards
what is osteomalacia / rickets
Osteomalacia describes softening of the bones secondary to low vitamin D levels that in turn lead to decreased bone mineral content. If this occurs in growing children it is referred to as rickets, with the term osteomalacia preferred for adults.
- leading to low Ca + hydroxyapitite mineralisation of bone
What are the 5 causes of osteomalacia?
1) HyperPTH
2) Vit D deficiency
3) CKD/Renal failure
4) Liver Failure
5) Anticonvulsant drugs
can be inherited
Symptoms of Rickets? (3)
Skeletal deformities:
- knocked knees
- bow legs
- wide epiphyses
Treatment for Osteomalacia? (2)
- Vit D replacement (calcitriol)
- Increase dietary intake (D3 tablets + eggs)
Symptoms of osteomalacia? (3)
- Fractures
- Proximal weakness
- Difficulty weight bearing
Osteomalacia vs Rickets? (2) anatomy
Osteomalacia = After epiphyseal fusion
Rickets = Before epiphyseal fusion
How does Vitamin D deficiency cause osteomalacia? (3)
- Most common cause
- Due to malabsorption/reduced intake/poor sunlight
- Results in decreased absorption of calcium from gut and decreased reabsorption in renal pct
Investigations to diagnose osteomalacia? (3)
- BM biopsy = incomplete mineralisation
- Bloods:
Increased PTH
Decreased serum Ca2+
Decreased 25-hydroxyvit D (best marker)
X ray = Looser’s zones (defective mineralisation)
How does liver dysfunction cause osteomalacia?
Reduced activation of vitamin D (25-hydroxylation)
How does hyperPTH cause osteomalacia? (2)
- Ca2+ released from bone so less available for mineral formation
- Seconadary reason is due to vit D deficiency
How does CKD/renal disease cause osteomalacia?
Reduced activation of vitamin D (1-alpha-hydroxylation)
How can anticonvulsive drugs cause osteomalacia?
Increase CYP450 metabolism of vitamin D
Draw out the Vitamin D pathway (4)
IBD + CKD + liver disease
IBD - less absorption from food
CKD + liver - less activation
look for in patients
darker skin
doesn’t leave the house
cold climates
covered skin
