Osteomalacia Flashcards
What is osteomalacia?
Condition with defective bone mineralisation causing ‘soft’ bones resulting from insufficient vitamin D.
What is this a presentation of?
Dark-skinned individual, muscle aches and weakness, abnormal fractures, spends a lot of time indoors.
Osteomalacia
What is the condition associated with osteomalacia called in children?
Rickets
Why are patients with darker skin more predisposed to osteomalacia?
Require a longer period of sun exposure to generate the same quantity of vitamin D.
In which disorders is vitamin D deficiency more common?
- Malabsorption disorders (e.g. IBS)
2. CKD
Why are patients with CKD more likely to be vitamin D deficient?
Because the kidneys activate vitamin D.
What does vitamin D do when active?
Increases calcium and phosphate absorption from the gut and kidneys, regulating bone turnover and promoting bone resorption.
What is the effect of vitamin D deficiency on PTH?
Decreases calcium which causes a secondary hyperparathyroidism, increasing resorption from bones and worsening condition.
What are Looser zones in osteomalacia?
Fragility fractures that go partially through bone.
What are the ranges for serum 25-hydroxyvitamin D deficiency/insufficiency?
- <25 nmol/L - deficiency
- 25-50 nmol/L - insufficiency
- > 75 - optimal
What happens to serum calcium, phosphate, ALP, and PTH in vitamin D deficiency?
- Calcium and phosphate low
- ALP may be high
- PTH may be high (secondary hyperparathyroidism)
What might an X-ray show in vitamin D deficiancy?
Osteopenia (more radiolucent bones)
What does a DEXA scan show in vitamin D deficiency?
Low bone mineral density
What is the treatment for vitamin D deficiency?
Cholecalciferol or alfacalcidol, acute high dose, then maintenance dose for life. Only maintenance dose for insufficiency.
