What is Osteomalacia

Osteomalacia is the adult counterpart of rickets in children. Both of these conditions are caused by a defect in vitamin D availability or metabolism. Osteomalacia is characterised by poor bone formation, resulting in weakened bone.

Statistics on Osteomalacia

Rickets and osteomalacia are bone diseases that occur worldwide; however, in developed countries they rarely occur as a result of dietary deficiency. The incidence of osteomalacia is approximately 1 in 1000 people.

Risk Factors for Osteomalacia

Risk of osteomalacia is increased by:

  • Inadequate dietary intake of vitamin D, for instance due to lactose intolerance
  • Inadequate exposure to sunlight (ultraviolet radiation), which produces vitamin D in the body (increased risk in elderly people who are housebound)
  • Malabsorption of vitamin D by the intestines
  • Inherited or acquired disorders of vitamin D metabolism
  • Advanced renal disease
  • Phosphate depletion associated with low dietary intake of phosphates
  • Certain medications such as those used to treat epilepsy

Progression of Osteomalacia

In adults, the vitamin D deficiency results in abnormal bone formation, which is weaker than healthy bone. There is increased risk of fractures, which tend to affect the vertebral bodies in the spine and the neck of femur. If osteomalacia persists, it may result in lower density bone and subsequently osteoporosis.

How is Osteomalacia Diagnosed?

Diagnosis is made on the basis of clinical and physical findings and further tests. Tests include:

  • Blood tests to measure calcium, phosphate and vitamin D levels in the blood
  • X-rays of the pelvis, spine and long bones which may show reduced bone density and changes characteristic of osteomalacia
  • Bone biopsy if the above tests are inconclusive.

Prognosis of Osteomalacia

Prognosis is good if underlying causes of vitamin D deficiency are addressed. Patients should be encouraged to eat a balanced diet and ensure adequate sun exposure.

How is Osteomalacia Treated?

Treatment should be aimed at correcting any underlying cause where possible. Osteomalacia due to poor intake is reversed by ensuring adequate diet, sunlight exposure and vitamin D and calcium supplements if necessary.

Osteomalacia References

  1. Kumar and Clark. Clinical Medicine, 5th ed. WB Saunders, Toronto (2002).
  2. Apley, Solomon. Concise system of orthopaedics and fractures, 2nd ed. Arnold, London (2001).
  3. Cotran, Kumar, Collins. Robbins Pathological Basis of Disease, 6th ed. WB Saunders, United States of America (1999).
  4. Kline M. Osteomalacia and Renal osteodystrophy. eMedicine 2001 [available online @ http://www.emedicine.com/radio/topic500.htm]