Metabolic Bone Disease in preterm newborn: an update on nutritional issues

Metabolic bone disease: a continued challenge in extremely low birth weight infants

BACKGROUND

Metabolic bone disease (MBD) is an important prematurity-related morbidity, but remains inadequately investigated in extremely low birth weight (ELBW) infants, the group most at risk. The objective was to describe the incidence and associated risk factors of MBD in ELBW infants.

METHODS

Retrospective analysis of all ELBW infants admitted between January 2005 and December 2010 who survived > 8 weeks. MBD was defined as the presence of osteopenia or rickets in radiographs.

RESULTS

Of the 230 infants included in the study, 71 (30.9%) developed radiological evidence of MBD (cases) of which 24/71 (33.8%) developed spontaneous fractures. MBD and fractures were noted at mean postnatal ages of 58.2 ± 28 and 100.0 ± 61 days, respectively. Compared with controls, cases were smaller at birth (664.6 ± 146 g vs 798.1 ± 129 g), more premature (25.0 ± 1.8 vs 26.4 ± 1.9 weeks), more frequently associated with mechanical ventilation, chronic lung disease, parenteral nutrition days, cholestasis, furosemide, postnatal steroids, and antibiotics use (all P < .01). Cases had lower average weekly intake of calcium, phosphorous, vitamin D, protein, and calories during the first 8 weeks of life compared with controls. Cases with MBD, compared with controls, had higher mortality (14.1 vs 4.4%) and longer hospital stay (140.2 ± 51 vs 101.0 ± 42 days; P < .01).

CONCLUSIONS

MBD remains an important morbidity in ELBW infants despite advances in neonatal nutrition. Further research is needed to optimize the management of chronic lung disease and early nutrition in ELBW infants.

Inside the "fragile" infant: pathophysiology, molecular background, risk factors and investigation of neonatal osteopenia

Current research in bone mineral metabolism reveals many aspects of osteopenia occurred in premature infants. This review examines not only the pathophysiological and molecular mechanisms of newborn osteopenia but also the risk factors and investigation. Osteopenia of premature infants has increased incidence among other diseases of prematurity. Identification of risk factors is essential for monitoring of osteopenia. Some of the risk factors include low birth weight, prematurity, long term administration of drugs such as corticosteroids, methyloxanthines, furosemide, abnormalities in vitamin D metabolism, poor maternal nutritional and mineral uptake etc. Neonatologists, pediatricians and endocrinologists should investigate premature, low birth weight infants that have high serum alkaline phosphatase and have at least one risk factor.

Parathyroid hormone levels in neonates with suspected osteopenia

AIM

The goal of this study is to describe secondary hyperparathyroidism in extremely low birthweight (ELBW) neonates and their response to enteral calcium carbonate (CaCO(3)) supplementation.

METHODS

A retrospective case series was conducted on extremely low birth infants, <1000 g birthweight, who survived hospitalisation, had no major congenital anomalies and had all their care in our institution

RESULTS

During this 6-year period, 231 ELBW infants survived hospitalisation at our institution. Of the 231 patients, parathyroid hormone (PTH) levels were performed in 66 of these patients (29%) and were elevated in 54 patients (82% of those tested). The timing of this testing was sporadic and was often performed after recognising osteopenia on radiography. Of the 54 patients with high PTH levels, 44 (81%) were treated with CaCO(3) and PTH levels were monitored while on therapy. The average duration of therapy was 41 ± 28 days, with 64% of PTH levels returning to normal before discharge.

CONCLUSIONS

PTH is a major hormone responsible for bone resorption, and serum levels may be a useful marker in identifying ELBW neonates at risk for metabolic bone disease. ELBW neonates with secondary hyperparathyroidism may benefit from enteral supplementation with CaCO(3). Further studies are needed to better evaluate the incidence, timing and potential treatment of hyperparathyroidism in ELBW infants.

Efficacy of intermediate-dose oral erythromycin on very low birth weight infants with feeding intolerance

BACKGROUND

Erythromycin is generally used as a prokinetic agent for the treatment of feeding intolerance in preterm infants; however, results from previous studies significantly vary due to different medication dosages, routes of administration, and therapy durations. The effectiveness and safety of intermediate-dose oral erythromycin in very low birth weight (VLBW) infants with feeding intolerance was examined in this study.

METHODS

Between November 2007 and August 2009, 45 VLBW infants with feeding intolerance, who were all at least 14 days old, were randomly allocated to a treatment group and administered 5mg/kg oral erythromycin every 6hours for 14 days (n=19). Another set of randomly selected infants was allocated to the control group, which was not administered erythromycin (n=26).

RESULTS

The number of days required to achieve full enteral feeding (36.5±7.4 vs. 54.7±23.3 days, respectively; p=0.01), the duration of parenteral nutrition (p<0.05), and the time required to achieve a body weight ≥2500g (p<0.05) were significantly shorter in the erythromycin group compared with the control group. The incidence of parenteral nutrition-associated cholestasis (PNAC) and necrotizing enterocolitis (NEC) ≥ stage II after 14 days of treatment were significantly lower (p<0.05) in the erythromycin group. No significant differences were observed in terms of the incidences of sepsis, bronchopulmonary dysplasia, or retinopathy of prematurity. No adverse effects were associated with erythromycin treatment.

CONCLUSIONS

Intermediate-dose oral erythromycin is effective and safe for the treatment of feeding intolerance in VLBW infants. The incidences of PNAC and ≥ stage II NEC were significant lower in the erythromycin group.

Fetal and neonatal bone health: update on bone growth and manifestations in health and disease

The neonatal period is classically described as the first 28 days of life, but owing to the fact that changes in skeletal tissue occur at a somewhat slower pace than those of other organ systems, events of the first few months are considered herein. Neonatal bone health is a problem of growing interest and concern because of the increasing recognition of its impact upon childhood, adolescent and even adult bone health. Osteoporosis in adulthood often has its roots in childhood and some forms may be prevented by proper attention to neonatal and childhood bone health. The premature infant likely suffers lifelong decreased bone mineral density as a result of its early birth and lack of adequate mineral stores that are typically present in full-term infants. Adequate embryogenesis, growth and development of the skeletal system are multifactorial and under the influence of a host of genes, growth factors and enzymes. The evaluation of skeletal dysplasias and their recognition are beyond the scope of this paper and will not be considered in this discussion. Here the focus will be on the adequacy of mineralization and metabolic aspects of the growth and development of the fetal and neonatal skeleton, the effect of birth, both preterm and term, maternal illness and health as well as infant diseases.

Calcium absorption in very low birth weight infants with and without bronchopulmonary dysplasia

OBJECTIVE

To evaluate the effects of early bronchopulmonary dysplasia (BPD) on calcium (Ca) metabolism and growth in very low birth weight (VLBW) infants.

STUDY DESIGN

A dual-tracer, stable isotope method was used to assess Ca absorption in VLBW infants. Infants with early BPD received energy-dense feedings and mild fluid restriction.

RESULTS

Sixteen of 41 preterm infants were classified as having early BPD. Fractional Ca absorption (early BPD, 58.4 ± 4.6% versus no early BPD, 50.3 ± 4.0%, P = .2), total Ca absorption (early BPD, 127 ± 14 mg/kg/d versus no early BPD, 104 ± 9 mg/kg/d, P = .9), and Ca retention (early BPD, 99.6 ± 10.0 mg/kg/d versus no early BPD, 91.0 ± 9.8 mg/kg/d, P = .2) were similar among groups. There was no significant difference in weight gain, linear growth, or head circumference growth between groups.

CONCLUSIONS

The ability of VLBW infants with early BPD and fluid restriction to grow and accrete calcium is similar to those without early BPD. The use of high caloric density feedings in VLBW infants with early BPD can help achieve bone and overall growth outcomes close to those achievable in utero.