21st July 2023

Osteomalacia

Osteomalacia is a disease of reduced bone mineralisation in adults; this is known as rickets disease in children. The most common cause is vitamin D deficiency which can lead to other electrolyte deficiencies and pH imbalances. Vitamin D is obtained from both diet and sunlight and is metabolised in the liver and kidneys. Therefore, risk factors include conditions that would impair vitamin D absorption in the GI tract, or vitamin D activation in the liver and renal system. Atypical causes include drug induced (due to the induction of liver enzymes), vitamin D resistance and tumour induced osteomalacia.

Investigations include blood tests to assess vitamin D levels, renal profile, bone profile, electrolytes, and parathyroid hormone. Vitamin D, serum Calcium and phosphate would be low. ALP and PTH would be elevated. Abnormal renal function and or electrolytes may suggest other underlying causes, such as chronic renal failure or renal tubular acidosis.

An X-ray will show signs of pseudo fractures, such as Looser zones and codfish vertebrae (concavity of the vertebral bodies).

Osteomalacia presents vague symptoms, including fatigue, generalised bone pain, muscle weakness, proximal myopathy, waddling gait, cramps, muscle spasms and paraesthesia.

Lifestyle modifications such as increased exposure to sunlight and eating food rich in calcium and vitamin D play a role in preventing osteomalacia. However, pharmacological intervention is required if the vitamin D deficiency is severe or results in symptoms. This involves treatment with a loading dose of vitamin D followed by a maintenance regime. Calcium supplementation will be required if serum calcium levels are low; this can be given in a combined formulation with Vitamin D. Additionally, managing any underlying causes of vitamin D deficiency is important.