Osteomalacia

Question 1

What is it?

Answer 1

Osteomalacia is a condition where there is defectivebone mineralisation causing “soft” bones.

This results from insufficientvitamin D. It presents with weak bones, bone pain, muscle weakness and fractures.

Question 2

What is this condition called when it occur before the growth plates fuse (children)?

Answer 2

Rickets

Question 3

What is Vitamin D ? Where is it produced?

Answer 3

Vit D is a hormone made by the skin from cholestrol in response to UV light

Pt with darker skin need more sun exposure to produce the same quantity of vit D

A standard diet does not contain adequate levels of vit D to compensate for lack of sun exposure.

Question 4

What does vit D do in the body?

Answer 4

• essential incalcium andphosphate absorption from theintestines anddecreased excretion from kidneys
• responsible for regulating bone turnover and increased Calcitriol promotes bone reabsorption to boost the serum calcium level

Question 5

What happens when deficient in vit D?

Answer 5

• Insufficient Vit D leads to low calcium and phosphate in blood- lost in kidney and gut
• This will lead to defective bone mineralisation.
• Low calcium causes Secondary hyperparathyroidism- PT gland tries to raise calcium level by increasing secretion of PTH
• Parathyroid hormone stimulates increased reabsorption from the bones- increases the problem

Question 6

Causes of deficiency?

Answer 6

• Reduced sun exposure without vit D supplementation
• Malabsorption disorders (eg. IBD) more likely to cause
• CKD- kidneys need to metabolise vit D into its active form

Question 7

Risk factors for vit D deficiency

Answer 7

• Darker skin
• Low exposure to sunlight
• live in colder climates
• spend a lot of time indoors

Question 8

Symptoms of osteomalacia

Answer 8

• Fatigue
• Bone pain
• Muscle weakness
• Muscle aches
• Pathological or abnormal fractures

Question 9

What tests would you order?

Answer 9

• Serum 25-hydroxyvitamin D
• Serum calcium - low
• Serum phosphate - low
• Serum alkaline phosphatase- may be high
• Parathyroid hormone- may be high (secondary hyperparathyroidism)
• X-rays- can show osteopenia (more radiolucent bones)
• DEXA scan shows low bone mineral density

Question 10

management ?

Answer 10

Supplementary vitamin D (colecalciferol) and calcium carbonate