The diagnosis of rickets or osteomalacia may be suspected from the presence of a painful deforming bone disease that is associated with characteristic abnormalities of serum chemistry. In patients with malabsorption or dietary deficiency of vitamin D, serum 25-hydroxyvitamin D is an important measurement since it reflects the major transport form of vitamin D in the circulation. It is also a good parameter of gut absorption of vitamin D. X-Rays may be characteristic in children with rickets and in some adult patients with osteomalacia who develop pseudofractures. However, pseudofractures are uncommon, and in patients in whom osteomalacia is suspected on clinical or radiological grounds, it may be