Osteomalacia / Rickets
Vitamin D deficiency results in myopathy (proximal weakness) and musculoskeletal aches and pains and children are often miserable. Rickets can result in classical signs of bow legs and swollen joints. Radiographs may show widened metaphyses. The causes may be due to malabsorption (e.g coeliac disease, inflammatory bowel disease), dietary deficiency, inadequate sun exposure, renal disease and drugs (e.g. antiepileptic drugs). There are also inherited forms.
Investigations include bone chemistry (serum calcium, phosphate, alkaline phosphatase, parathyroid hormone and 25 hydroxyvitamin D). The threshold for vitamin D deficiency in asymptomatic individuals is controversial.