Incidence of metabolic bone disease in preterm infants of birth weight

Abstract

Preterm infants are exposed to a higher risk of developing Metabolic Bone Disease (MBD) with an increased bone fragility, a higher fracture risk and a long-term reduced linear growth and childhood height. Monitoring bone growth has become mandatory in neonatology. Several risk factors have been identified among the population of extremely low birth weight infants, but we still do not know which is the real incidence of MBD since its evaluation is not routinely performed worldwide. The aim of this study was to evaluate the incidence of MBD in preterm infants and in those suffering from bronchopulmonary dysplasia (BPD). Prospective evaluation of patients who developed BPD (BPD group) versus infants who did not develop it (no-BPD group). We examined, in preterms <1.250g, the metacarpus bone transmission time (mc-BTT) at birth, 21 days and 36 weeks of gestational age (GA) together with biochemical markers of bone status. We included 135 patients, 55 with BPD. BPD patients received less total proteins in the first two weeks and less energy in the first month of life (p=0.007 and p<0.001 respectively). BPD patients had a worse growth velocity at two weeks of age (12.36±7.86 vs 16.59±7.05g/kg/day, p=0.001). At 21 days, BPD patients had lower phosphatemia (1.65±0.031mmol/L vs 1.85±0.034mmol/L, p=0.007) and higher alkaline phosphatase levels (411.62±135.31IU/l vs 338.98±102.20IU/l, p=0.005). BPD patients had significantly worse mc-BTT at 36weeks GA (0.45±0.06 vs 0.50±0.08μsec, p<0.001) and a higher incidence of MBD (60% vs 34%; p=0.012). BPD infants are a special subset of patients among preterms who receive, in the first month of life, a lower energy intake than patients without BPD. BPD patients have a suboptimal bone growth and a higher incidence of MBD. Monitoring growth, bone status and optimizing nutritional intakes need to be further improved in preterm infants with BPD.