osteomalacia Flashcards
what is osteomalacia
- defective bone mineralisation
- causes soft bones
- caused by vitamin D deficiency
roles of vitamin D
- calcium and phosphate absorption in the intestines
- calcium and phosphate reabsorption in kidneys
conditions making patients more at risk of vitamin D deficiency
IBD - less absorption in intestines
CKD - less reabsorption in kidneys
how does vitamin D deficiency directly lead to bone destruction
low vitamin D - less calcium absorption and reabsorption
increases PTH release
bone destruction
presentation
may be asymptomatic
- fatigue
- bone pain
- muscle weakness
- muscle aches
- abnormal / pathological features
in patient presentation - what to look out for
- dark skin
- low exposure to sunlight
- vegan / diet
- colder climates
investigations
serum 25-hydrodeoxyvitaminD
< 25 - deficiency
25-50 - insufficiency
xray - osteopenia - translucent bands / loosers zones
DEXA - low bone mineral density
raised serum alkaline phosphatase
low calcium
low phosphate
BM biopsy = incomplete mineralisation
whats found on an xray
translucent bands
loosers zones
treatment
colecalciferol
- Increase dietary intake (D3 tablets + eggs)
causes
1) HyperPTH
2) Vit D deficiency
3) CKD/Renal failure
4) Liver Failure
5) Anticonvulsant drugs
symptoms
- Fractures
- Proximal weakness
- Difficulty weight bearing
osteomalacia vs rickets
Osteomalacia = After epiphyseal fusion
Rickets = Before epiphyseal fusion
How does liver dysfunction cause osteomalacia?
Reduced activation of vitamin D (25-hydroxylation)
How can anticonvulsive drugs cause osteomalacia?
Increase CYP450 metabolism of vitamin D
draw out vitamin D activation pathway
secondary hyperparathyroidism due to chronic kidney disease
chronic kidney disease
- reduced phosphate excretion because tubules damaged
- reduced vitD activation
- so, therefore, reduced Ca absorption
- inc PTH release
- hypocalcaemia
- hyperphosphataemia
- elevated alkaline phosphatase
- elevated PTH
presentation
- A waddling gait
- Proximal muscle weakness
- Generalised bone and joint tenderness
- Signs of hypocalcaemia (e.g. tetany, carpopedal spasm)
- Spinal deformities e.g. kyphoscoliosis
foods rich in vitamin D
1️⃣ Oily Fish 🐟
2️⃣ Egg Yolks 🍳
3️⃣ Fortified Dairy & Plant Milk 🥛
4️⃣ Mushrooms 🍄
5️⃣ Cod Liver Oil 🥄
level of vitamin D deficiency and insufficiency
< 25 - deficiency
25-50 - insufficiency
whats found on bone marrow biposy
incomplete mineralisation
