Osteomalacia

Question 1

Define 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.

Question 2

Explain the aetiology/risk factors of osteomalacia.

Answer 2

Dietary calcium and vitamin D deficiency
Chronic kidney disease
Limited sunlight exposure
Inherited disorders of vitamin D and bone metabolism
Hypophosphatasia
Anticonvulsant therapy

Question 3

Summarise the epidemiology of osteomalacia.

Answer 3

In the US and Europe, more than 40% of the adult population older than age 50 years are vitamin D deficient, this being the most prominent cause of osteomalacia. In developing countries, such as Tibet and Mongolia, vitamin D deficiency leading to clinical rickets is reported in 60% of infants.

Question 4

Recognise the presenting symptoms of osteomalacia. Recognise the signs of osteomalacia on physical examination.

Answer 4

Old age
Vitamin D and calcium deficient diets
Lack of sunlight exposure
Fractures
Malabsorption syndromes
Diffuse bone pain and tenderness
Proximal muscle weakness
Family history of osteomalacia
Waddling gait

Question 5

Identify appropriate investigations for osteomalacia and interpret the results.

Answer 5

Serum calcium level
Serum 25-hydroxyvitamin D level
Serum phosphate level
Serum urea and creatinine
Intact PTH
Serum alkaline phosphatase
24-hour urinary calcium