Rickets and osteomalacia

This chapter describes definition, etiology, pathophysiology, diagnosis, treatment and prevention of nutritional rickets and osteomalacia. Rickets and osteomalacia (from Greek osteon and malakia, bone softness) are diseases characterized by hypomineralization of bone matrix. Rickets occurs only in children (before epiphyseal closure) and additionally leads to abnormal growth plate development, stunting, and bone deformities. The causes of osteomalacia and rickets are similar and can be classified according to underlying mechanisms: Vitamin D deficiency or resistance; calcium deficiency independent of vitamin D; hypophosphatemic disorders; and mineralization inhibitors. Patients with rickets and osteomalacia related to vitamin D deficiency typically have very low serum 250-hydroxyvitamin D (25OHD) concentrations, that is below 15 to 30?nmol/L. Vitamin D deficiency rickets responds to small doses of vitamin D. Nutritional osteomalacia may be treated with remarkably low doses of calcium and vitamin D.