Nutritional aspects of metabolic bone disease in the newborn.

Correspondence to: Dr Steven Ryan. Metabolic bone disease (MBD) in the newborn predominantly affects preterm neonates, although there are a few reports of babies with congenital rickets after maternal vitamin D deficiency. Features of MBD in preterm neonates include radiological abnormalities such as fractures, rickets, and osteoporosis; biochemical features such as raised blood alkaline phosphatase activity or hypophosphataemia; skeletal deformity such as rib cage softening and altered head shape; and diminished linear growth velocity. MBD can arise from insufficient dietary minerals (calcium and or phosphorus), too little collagen, or abnormal collagen. MBD mainly arises from dietary mineral deficiency in the newborn, although copper deficiency, as a result of abnormal collagen metabolism, has also been implicated. It is difficult to differentiate these two processes, because they often occur in the same patient. The pathology ofMBD in preterm neonates shows generalised skeletal mineralisation, a reduction in the amount of osseous tissue (osteoporosis), and a disordered metaphyseal cartilage plate similar to that seen in classic rickets. I