Osteomalacia Flashcards
What is osteomalacia?
A condition where defective bone mineralisation causes ‘soft’ bone
What does ‘osteo’ mean and what does ‘-malacia’ mean?
‘Osteo’ means bone, and ‘-malacia’ means soft
What is the primary cause of osteomalacia?
Insufficient vitamin D
What condition does insufficient vitamin D cause in children?
Rickets
How is vitamin D created in the body?
Created from cholesterol by skin in response to UV radiation
How can vitamin D be obtained aside from synthesis in the skin?
Obtained from food as a fat-soluble vitamin
What is the function of vitamin D?
Calcium and phosphate absorption in intestines and reabsorption in kidneys
What are risks associated with low vitamin D levels?
Malabsorption disorders
What does low vitamin D lead to?
Low calcium and phosphate, leading to defective bone mineralisation → osteomalacia
What is the effect of low calcium levels in the body?
Increased PTH (secondary hyperparathyroidism) promotes calcium reabsorption from bone
What are common clinical features of osteomalacia?
- Fatigue
- Bone pain
- Muscle weakness
- Muscle aches
- Pathological or abnormal fractures
What are looser zones in osteomalacia?
Fragility fractures going partially through bone
What is the test for serum 25-hydroxyvitamin D levels indicating vitamin D deficiency?
> 25nmol/L indicates vitamin D deficiency
What serum level range indicates vitamin D insufficiency?
25-50nmol/L
What other tests may show abnormalities in osteomalacia?
- Low calcium
- Low phosphate
- High alkaline phosphatase
- High parathyroid hormone
What imaging techniques are used in the investigation of osteomalacia?
- X-rays → osteopenia
- DEXA → low bone mineral density
What is the treatment for osteomalacia?
Colecalciferol (vitamin D3)
What is a common loading dose of colecalciferol for osteomalacia?
50,000 once daily for 6 weeks
What is a common maintenance dose of colecalciferol?
800-20,000 daily
