Neonatal osteopenia

**Definition:** Metabolic bone disease is a common complication in very low birthweight (VLBW) preterm infants. The smallest, sickest infants are at greatest risk. Progressive osteopenia with demineralized bones and, occasionally, pathologic fractures may develop. The major cause is inadequate intake of calcium and phosphorus to meet the requirements for growth. Poor intake of vitamin D is an additional risk factor. Contributing factors include prolonged parenteral nutrition, vitamin D and calcium malabsorption, intake of unsupplemented human milk, immobilization, and urinary calcium losses from long-term diuretic use.

**Long definition:** The transfer of calcium and phosphorus from mother to fetus occurs throughout pregnancy, but 80% occurs during the third trimester. Premature birth interrupts this process, with rickets developing when the premature infant does not have an adequate supply of calcium and phosphorus to support mineralization of the growing skeleton.