Osteomalacia

Osteomalacia is a disorder of bone mineralization and is due to a lack of vitamin D. Vitamin D is a prohormone formed by the action of UV radiation on the vitamin’s precursor (7-dehydrocholesterol) in the skin. It undergoes two hydroxylation steps to become an active hormone. The commonest cause of osteomalacia is vitamin D deficiency due to a lack of UVB skin exposure. Other causes include malabsorption (coeliac disease and pancreatic insufficiency), obesity, and chronic kidney disease. The typical symptoms of osteomalacia are non-specific bone pain, proximal myopathy, fatigue, and polyarthralgia. This chapter addresses the causes, diagnosis, and management of osteomalacia.