Osteomalacia

Question 1

What is osteomalacia?

Answer 1

Osteomalacia is a metabolic bone disease characterised by incomplete mineralisation of the underlying mature organic bone matrix (osteoid) following growth plate closure in adults. 

(In osteoporosis, bone mass decreases, but the ratio of bone mineral to bone matrix is normal. In osteomalacia, the ratio of bone mineral to bone matrix is low.)

Question 2

What are the causes of osteomalacia?

Answer 2

1. Rickets → disorder of impaired mineralisation of cartilaginous growth plates (only occurs in children)
2. Vitamin D Deficiency → reduced exposure to sunlight, low dietary intake, reduced intestinal absorption (coeliac disease, chronic pancreatitis)
3. Defective Vitamin D Metabolism → liver cirrhosis, CKD
4. Drugs → anticonvulsants

Question 3

What are the presenting symptoms of osteomalacia?

Answer 3

• Bone pain & tenderness
• Pathological fractures → occur with mild trauma. Especially femoral neck.
• Proximal Myopathy → muscle weakness, spasms, cramps. May lead to waddling gait.
• Fatigue
• Symptoms of Hypocalcaemia (due to vit D deficiency) → tetany, muscle twitching, paraesthesia, arrhythmias (CATs go Numb)

Question 4

What investigations are used to diagnose/ monitor osteomalacia?

Answer 4

1. Bloods
   - low vitamin D levels
   - low calcium and low phosphate
   - raised ALP
   - raised PTH (secondary hyperparathyroidism)
2. May see Looser Zones (pseudofractures) on X-Ray

Question 5

How is osteomalacia managed?

Answer 5

Treat Vitamin D deficiency:
- Vitamin D Supplementation (+ calcium if dietary calcium is inadequate) ⇒ Ergocalciferol/Colecalciferol (+Calcium Carbonate/Calcium Citrate)

Question 6

What complications may arise from osteomalacia?

Answer 6

• pseudofractures
• hypercalcaemia
• secondary hyperparathyroidism