Osteomalacia – Weak Bones

Osteomalacia is a condition of low mineralisation of bone after growth has ceased. If it occurs in children and adolescents, it is called rickets. Untreated osteopenia may result in osteoporosis, the condition in which the bone mass is reduced to such a level that the skeletal integrity is lost.

Causes

Osteomalacia results from abnormal calcium and phosphorus metabolism caused by an abnormality of vitamin D, leading to development of weaker bones and increased risk of fracture and deformity. Usually there is an identifiable underlying cause.

If there is reduced sunlight exposure, the prevalence of dietary deficient osteomalacia is higher in women as compared to men.

There is either vitamin D deficiency due to inadequate diet and insufficient sunlight exposure (as vitamin D is synthesized in the skin on sun exposure) or a defect in conversion of vitamin D to its active form in the kidney (renal osteomalacia). In the latter form renal osteodystrophy may occur, which is a complex bone abnormality. Osteomalacia may also occur in association with tumors (though rarely).

Symptoms

Easy fracture, deformity (spine), bone pain (diffuse) and proximal muscle weakness are the most common symptoms.

There may be signs of some underlying disease such as poor nutrition, renal failure, malabsorption or liver disease.

Diagnosis

X-ray of bones shows osteopenia and pseudo-fractures. Serum calcium and phosphate may be low with an elevated alkaline phosphatase. Serum 25-hydroxyvitamin D is usually depressed. Bone biopsy shows reduced bone mineral and increased osteoid.

Treatment

Treatment for deficiency of vitamin D is by oral or intramuscular vitamin D supplements. Vitamin D analogues and/or Calcium can also be given.

Prognosis

If the diagnosis and treatment happen before complications such as bone deformity or fracture arise, osteomalacia may have a good prognosis. However, the underlying cause is significant, be it dietary or any other underlying disease. Lack of exposure to sunlight and/or poor diet indicates a self-neglect.