Osteomalacia

Question 1

What is osteomalacia?

Answer 1

Osteomalacia is a condition where defective bone mineralization causes ‘soft’ bones, typically resulting from vitamin D deficiency. The same process in children is known as rickets.

Question 2

What is the role of vitamin D in bone health?

Answer 2

Vitamin D is essential for calcium and phosphate absorption in the intestines and reabsorption in the kidneys. It regulates bone turnover and promotes bone reabsorption to increase serum calcium levels.

Question 3

What causes osteomalacia?

Answer 3

Osteomalacia is caused by insufficient vitamin D, leading to low serum calcium and phosphate, impairing bone mineralization. This results in weakened, soft bones.

Question 4

What are the risk factors for vitamin D deficiency and osteomalacia?

Answer 4

• Darker skin (requires more sun exposure)
• Low sun exposure or living in colder climates
• Malabsorption disorders (e.g., inflammatory bowel disease)
• Chronic kidney disease
• Low dietary intake of vitamin D

Question 5

What are the typical symptoms of osteomalacia?

Answer 5

• Fatigue
• Bone pain
• Muscle weakness
• Muscle aches
• Pathological fractures (bones break easily)

Question 6

What are Looser zones?

Answer 6

Looser zones are fragility fractures that partially go through the bone, commonly seen in osteomalacia.

Question 7

How is osteomalacia diagnosed?

Answer 7

• Serum 25-hydroxyvitamin D test:
  < 25 nmol/L = vitamin D deficiency
  25–50 nmol/L = vitamin D insufficiency
• Lab findings:
  Low serum calcium and phosphate
  High serum alkaline phosphatase
  High parathyroid hormone (secondary hyperparathyroidism)
• Imaging:
  X-rays may show osteopenia
  DEXA scan shows low bone mineral density

Question 8

What is the first-line treatment for osteomalacia?

Answer 8

The first-line treatment is colecalciferol (vitamin D₃). A loading dose is followed by a maintenance dose.

Question 9

What are loading doses for colecalciferol in osteomalacia treatment?

Answer 9

• 50,000 IU once weekly for 6 weeks
• 4000 IU daily for 10 weeks

Question 10

What is the maintenance dose for vitamin D after the loading regime?

Answer 10

The maintenance dose is 800-2000 IU per day, depending on patient needs.

Question 11

What should be checked 1 month after the loading dose of vitamin D for osteomalacia?

Answer 11

Check the serum calcium to assess for:
* Low calcium (calcium deficiency)
* High calcium (in primary hyperparathyroidism or other conditions like cancer, sarcoidosis, tuberculosis)