Osteomalacia and Rickett's

Question 1

What is osteomalacia?

Answer 1

Osteomalacia is a qualitative bone defect with abnormal softening of the bone due to deficient mineralisation of osteoid (Immature bone), secondary to inadequate calcium and phosphorus (Caused by vitamin D deficiency)

Question 2

What is Rickett’s?

Answer 2

Osteomalacia occurring in children, which has subsequent effects on the growing skeleton

Question 3

What are some causes of hypophosphataemia?

Answer 3

• Re-feeding syndrome
• Alcohol abuse (Impairs phosphate absorption)
• Malabsorption
• Renal tubular acidosis

Question 4

What are soem conditions and factors that can predispose to osteomalacia?

Answer 4

• Long term anticonvulsants
• Chronic kidney disease
• X-linked hypophosphataemia
• Vitamin D resistant Rickett’s

Question 5

How does normal vitamin D prevent osteomalacia?

Answer 5

Vitamin D stimulates absorption of calcium from the GI tract, kidney and bone

It also induces osteoblasts to release osteocalcin

Question 6

Describe how vitamin D deficiency can lead to osteomalacia

Answer 6

Vitamin D deficiency ->

Hypocalcaemia and elevated PTH ->

Increased calcium absorption, osteoclastic activity and release of Ca2+ from bone ->

Impaired mineralisation of newly formed osteoid (Thick osteoid seams) + reduction in renal calcium loss + increase in renal excretion of phosphate ->

Impaired bone mineralisation + partially mineralised bone remodelling

Question 7

What are some presentations of osteomalacia and Rickett’s?

Answer 7

Bone pain (Pelvis, spine, femur)
Symptoms of hypocalcaemia
Pathological fracture

Question 8

What are some symptoms of hypocalcaemia?

Answer 8

• Parasthaesia
• Muscle cramps
• Irritability
• Fatigue
• Seizures
• Brittle nails

Question 9

What are some signs on osteomalacia and Rickett’s?

Answer 9

Bone deformity
Proximal myopathy
Dental defects

Question 10

What are some investigations required in osteomalacia and Rickett’s?

Answer 10

X-ray
Blood testing

Question 11

What will blood testing show in osteomalacia and Rickett’s?

Answer 11

Reduced calcium
Reduced serum phosphates
Increased serum ALP

Question 12

What will X-ray show on osteomalacia and Rickett’s?

Answer 12

Pseudofractures (Looser’s zones) - Pubic rami, proximal femur, ulna and ribs

Poor coptic-medullar differentiation

Question 13

How is osteomalacia and Rickett’s managed?

Answer 13

Management involves vitamin D therapy with calcium and phosphate supplementation:

• D3 tablets (400-800IU per day after loading with 3200IU per day for 12 weeks) - calcitriol (1-25 dehydroxycholecalciferol), alfacalcidol (1⍺ hydroxycholecalciferol)
• Combined vitamin D and calcium tablets e.g. adcal D3