Enteral calcium, phosphate and vitamin D requirements and bone mineralization in preterm infants

Nutritional requirements and feeding recommendations for small for gestational age infants

We define the small for gestational age (SGA) infant as an infant born ≥ 35 weeks' gestation and <10th percentile on the Fenton Growth Chart. Policy statements from many organizations recommend mother's own milk for SGA infants because it meets most of their nutritional requirements and provides short- and long-term benefits. Several distinct patterns of intrauterine growth restriction are identified among the heterogeneous grouping of SGA infants; each varies with regard to neonatal morbidities, requirements for neonatal management, postnatal growth velocities, neurodevelopmental progress, and adult health outcomes. There is much we do not know about nutritional management of the SGA infant. We need to identify and define: infants who have "true" growth restriction and are at high risk for adverse metabolic outcomes in later life; optimal growth velocity and "catch-up" growth rates that are conducive with life-long health and well being; global approaches to management of hypoglycemia; and an optimal model for postdischarge care. Large, rigorously conducted trials are required to determine whether aggressive feeding of SGA infants results in improved nutritional rehabilitation, growth, and neurodevelopmental outcomes. Before birth, maternal supplementation with specific nutrients reduces the rate and severity of growth restriction and may prevent nutrient deficiency states if infants are born SGA. After birth, the generally accepted goal is to provide enough nutrients to achieve postnatal growth similar to that of a normal fetus. In addition, we recommend SGA infants be allowed to "room in" with their mothers to promote breastfeeding, mother-infant attachment, and skin-to-skin contact to assist with thermoregulation.

Fractures in hospitalized children

Hospitalized children have multiple risk factors for fragility fractures, related to disease pathophysiology, treatments, nutritional status and immobilization. Recognition and treatment of these risk factors are important to prevent morbidity associated with fractures and to promote current and future bone health. Many knowledge gaps remain regarding the ideal nutrition, physical activity, and medication regimens needed to optimize bone health and reduce the risk of fractures over the life course. This article reviews the pathogenesis, risk factors, treatment and prevention strategies for fractures in hospitalized infants and children.

Bone mineral density and osteoporosis after preterm birth: the role of early life factors and nutrition

The effects of preterm birth and perinatal events on bone health in later life remain largely unknown. Bone mineral density (BMD) and osteoporosis risk may be programmed by early life factors. We summarise the existing literature relating to the effects of prematurity on adult BMD and the Developmental Origins of Health and Disease hypothesis and programming of bone growth. Metabolic bone disease of prematurity and the influence of epigenetics on bone metabolism are discussed and current evidence regarding the effects of breastfeeding and aluminium exposure on bone metabolism is summarised. This review highlights the need for further research into modifiable early life factors and their effect on long-term bone health after preterm birth.

High incidence of rickets in extremely low birth weight infants with severe parenteral nutrition-associated cholestasis and bronchopulmonary dysplasia

Risk factors for rickets of prematurity have not been re-examined since introduction of high mineral formula, particularly in ELBW infants. We analyzed the incidence and the risk factors of rickets in extremely low birth weight (ELBW) infants. As a retrospective case-control study from 2004 to 2008, risk factors were analyzed in 24 patients with rickets versus 31 patients without. The frequency of rickets in ELBW infants was 24/55 (44%). Infants with rickets were diagnosed at 48.2 ± 16.1 days of age, and improved by 85.3 ± 25.3 days. By radiologic evaluation, 29% were grade 1 rickets, 58% grade 2 and 13% grade 3. In univariate analysis, infants with rickets had significantly higher incidence of patent ductus arteriosus, parenteral nutrition associated cholestasis (PNAC), severe PNAC and moderate/severe bronchopulmonary dysplasia (BPD). In multiple regression analysis, after adjustment for gestation and birth weight, rickets significantly correlated with severe PNAC and with moderate/severe BPD. Serum peak alkaline phosphatase levels were significantly elevated in rickets (P < 0.001). In ELBW infants, the incidence of rickets of prematurity remains high and the incidence of severe PNAC and moderate/severe BPD was significantly increased 18 and 3 times, respectively.

Tactile/kinesthetic stimulation (TKS) increases tibial speed of sound and urinary osteocalcin (U-MidOC and unOC) in premature infants (29-32weeks PMA)

Preterm delivery (<37 weeks post-menstrual age) is associated with suboptimal bone mass. We hypothesized that tactile/kinesthetic stimulation (TKS), a form of infant massage that incorporates kinesthetic movement, would increase bone strength and markers of bone accretion in preterm infants. Preterm, AGA infants (29-32 weeks) were randomly assigned to TKS (N=20) or Control (N=20). Twice daily TKS was provided 6 days per week for 2 weeks. Control infants received the same care without TKS treatment. Treatment was masked to parents, health care providers, and study personnel. Baseline and week two measures were collected for tibial speed of sound (tSOS, m/sec), a surrogate for bone strength, by quantitative ultrasound (Sunlight8000) and urine markers of bone metabolism, pyridinium crosslinks and osteocalcin (U-MidOC and unOC). Infant characteristics at birth and study entry as well as energy/nutrient intake were similar between TKS and Control. TKS intervention attenuated the decrease in tSOS observed in Control infants (p<0.05). Urinary pyridinium crosslinks decreased over time in both TKS and CTL (p<0.005). TKS infants experienced greater increases in urinary osteocalcin (U-MidOC, p<0.001 and unOC, p<0.05). We conclude that TKS improves bone strength in premature infants by attenuating the decrease that normally follows preterm birth. Further, biomarkers of bone metabolism suggest a modification in bone turnover in TKS infants in favor of bone accretion. Taken together, we speculate that TKS improves bone mineralization.

Hypercalcemia in extremely low birth weight neonates

Hypercalcemia is rare in neonates but may be associated with hypophosphatemia in Extremely low birth weight (ELBW) neonates who are on parenteral nutrition without adequate phosphate supplementation.

Metabolic bone disease of prematurity and secondary hyperparathyroidism

AIM

To illustrate, via case histories, the importance of laboratory investigations for the early diagnosis and management of metabolic bone disease (MBD).

METHODS

We report three cases of extreme premature infants with MBD.

RESULTS

These three infants had several risk factors for MBD of prematurity: very low birthweight, delayed enteral feeds, cholestatic liver disease, intolerance of fortification, the use of glucocorticoids and diuretics. Serum alkaline phosphatase and parathyroid hormone (PTH) were elevated despite relatively normal calcium and phosphate levels. These parameters were corrected with additional supplementation of calcium, phosphate and vitamin D.

CONCLUSIONS

Infants born extremely prematurely have significant calcium and phosphate depletion by the time they reach full term compared with the normal fetal accretion rate. This is exacerbated if there is poor tolerability to feeds where extra calcium and phosphate could not be added either by additives or via human milk fortifier. Serum calcium and phosphate levels may be normal despite inadequate intake or stores due to the counter-regulatory effect of PTH. In infants at risk of MBD, testing serum alkaline phosphatase, vitamin D and PTH with calcium and phosphate may assist in the monitoring and management of MBD.

Daily physical activity in low-risk pre-term infants: positive impact on bone strength and mid-upper arm circumference

BACKGROUND

Prevention of pre-term osteopenia is important because it results in ventilator dependency, fractures in long bones, softening of the ribs or respiratory failure due to bone breaks in newborns.

AIM

The aim of this study was to evaluate the changes in bone strength and anthropometric indices of very low birth-weight (VLBW) pre-term infants undergoing daily physical activity.

SUBJECTS AND METHODS

Forty VLBW and low-risk pre-term infants (n intervention group = 20, n control group = 20) with a birth weight of 800-1600 g and gestational age of 26-32 weeks were recruited. Pre-term infants in the control group were provided with standard nursing care whereas those in the intervention group received a daily physical activity programme in addition to standard nursing care during the study. Before and after the study, anthropometric indices and tibial speed of sound (SOS) values were measured.

RESULTS

In this study the tibial SOS values were found to be increased in the intervention group (p < 0.001) and decreased in the control group (p = 0.002). The increase in percentage of the mid-upper arm circumference of infants was significantly higher in the intervention group than in the control group (p < 0.001).

CONCLUSION

A daily physical activity programme increased SOS values of the tibia and mid-upper arm circumference in VLBW pre-term infants.

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.

Enteral nutrient supply for preterm infants: commentary from the European Society of Paediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition

The number of surviving children born prematurely has increased substantially during the last 2 decades. The major goal of enteral nutrient supply to these infants is to achieve growth similar to foetal growth coupled with satisfactory functional development. The accumulation of knowledge since the previous guideline on nutrition of preterm infants from the Committee on Nutrition of the European Society of Paediatric Gastroenterology and Nutrition in 1987 has made a new guideline necessary. Thus, an ad hoc expert panel was convened by the Committee on Nutrition of the European Society of Paediatric Gastroenterology, Hepatology, and Nutrition in 2007 to make appropriate recommendations. The present guideline, of which the major recommendations are summarised here (for the full report, see http://links.lww.com/A1480), is consistent with, but not identical to, recent guidelines from the Life Sciences Research Office of the American Society for Nutritional Sciences published in 2002 and recommendations from the handbook Nutrition of the Preterm Infant. Scientific Basis and Practical Guidelines, 2nd ed, edited by Tsang et al, and published in 2005. The preferred food for premature infants is fortified human milk from the infant's own mother, or, alternatively, formula designed for premature infants. This guideline aims to provide proposed advisable ranges for nutrient intakes for stable-growing preterm infants up to a weight of approximately 1800 g, because most data are available for these infants. These recommendations are based on a considered review of available scientific reports on the subject, and on expert consensus for which the available scientific data are considered inadequate.

Nephrocalcinosis in preterm neonates

The prevalence of nephrocalcinosis (NC) in preterm neonates in recent reports is 7-41%. The wide range in prevalence is a consequence of different study populations and ultrasound equipment and criteria, in addition to a moderate interobserver variation. NC in preterm neonates has a multifactorial aetiology, consisting of low gestational age and birth weight, often in combination with severe respiratory disease, and occurs as a result of an imbalance between stone-promoting and stone-inhibiting factors. A limited number of histological studies suggest that calcium oxalate crystals play an important role in NC in premature neonates. In 85% of children resolution of NC occurs in the first years of life. Prematurity, per se, is associated with high blood pressure, relatively small kidneys, and (distal) tubular dysfunction. In addition, NC in preterm neonates can have long-term sequelae for glomerular and tubular function. Long-term follow-up of blood pressure and renal function of prematurely born children, especially with neonatal NC, is recommended. Prevention of NC with (low) oral doses of citrate has not resulted in a significant decrease in the prevalence of NC; a higher citrate dosage deserves further study. Future research pertaining to prevention of NC in preterm neonates is crucial.

Comparação entre duas dietas à base de leite humano em relação ao crescimento e à mineralização óssea de recém-nascidos de muito baixo peso

OBJETIVO: Comparar a eficácia e tolerabilidade de duas dietas à base de leite humano (LH) acrescido de fórmula láctea (PreNan®) ou complemento nutricional especial (FM 85®) na promoção do crescimento pôndero-estatural, mineralização óssea e tempo de hospitalização de recém-nascidos de muito baixo peso (RNMBP). MÉTODO: Foram constituídos, por sorteio, dois grupos de crianças acompanhadas a partir do 15º dia de vida, até atingir o peso de alta (2000±20g): Grupo A, 14 RNMBP receberam LH+FM 85® (5g/100mL LH); Grupo B, 11 RNMBP receberam LH+PreNan® 19% em volumes iguais. Foram avaliados: peso, comprimento, perímetro cefálico e prega cutânea tricipital média esquerda, calculando-se os incrementos de peso e o tempo para atingir 2000g. Foram dosados: cálcio, fósforo, magnésio e creatinina séricos e urinários e fosfatase alcalina sérica, calculando-se as taxas de reabsorção tubular de fósforo (%TPR). A mineralização óssea foi avaliada por meio de técnicas radiológicas padronizadas. RESULTADOS: 11 RNMBP de cada grupo completaram o estudo. Ambas as dietas foram bem toleradas e os índices antropométricos e dosagens séricas iniciais não apresentaram diferenças entre os grupos. Os incrementos de peso do Grupo B foram superiores aos do Grupo A e a fosfatase alcalina sérica do Grupo A foi maior que do Grupo B no final da observação. Não houve diferenças entre os grupos quanto à %TPR; mineralização óssea e tempo de hospitalização. CONCLUSÕES: Ambas as dietas foram bem toleradas. O leite humano enriquecido com PreNan® 19% volume a volume (v/v) se mostrou mais eficiente em relação ao ganho de peso e ao metabolismo ósseo em comparação ao leite humano acrescido de FM 85®.

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

Osteopenia, a condition characterised by a reduction in bone mineral content, is a common disease of preterm babies between the tenth and sixteenth week of life. Prematurely born infants are deprived of the intrauterine supply of minerals affecting bone mineralization.The aetiology is multifactorial: inadequate nutrients intake (calcium, phosphorus and vitamin D), a prolonged period of total parenteral nutrition, immobilisation and the intake of some drugs.The diagnosis of metabolic bone disease is done by biochemical analysis: low serum levels of phosphorus and high levels of alkaline phosphatase are suggestive of metabolic bone disease. The disease can remain clinically silent or presents with symptoms and signs of rachitism depending on the severity of bone demineralisation.An early nutritional intervention can reduce both the prevalence and the severity of osteopenia.This article reviews the pathophysiology of foetal and neonatal bone metabolism, focuses on the nutrient requirements of premature babies and on the ways to early detect and treat osteopenia.

Quantitative ultrasound (QUS): a useful tool for monitoring bone health in preterm infants?

Preterm infants are at risk of osteopenia and metabolic bone disease (MBD) of prematurity. There is a need for simple, reliable methods to detect and monitor this condition.

AIMS

The aims were first to describe longitudinal changes in speed of sound (SOS) measured using quantitative ultrasound (QUS; Sunlight Omnisense, Israel) in preterm neonates: and second to determine whether SOS predicts the development of MBD.

METHODS

SOS was measured in the tibia in 99 preterm infants (mean (SD)) gestation 29.7 (3.6) weeks; birthweight 1340 (550) g, with longitudinal measurements in 75. SOS z-scores were generated for gestation and sex. Clinical data were recorded.

RESULTS

Baseline SOS (but not SOS z-score) was positively associated with gestational age. SOS and SOS z-score fell with age. In multivariate models, peak ALP, minimum phosphate concentrations and markers of illness severity were not predictors of the fall in SOS z-score, and baseline SOS measurements did not predict the development of high peak ALP or low phosphate.

INTERPRETATION

Speed of sound measurements fell with age in all infants, but we found no evidence that this measurement could predict biochemical indicators of MBD. We cannot exclude the possibility that this technique could be useful in monitoring the response to interventions designed to improve bone health in this population.

Maternal-administered physical activity enhances bone mineral acquisition in premature very low birth weight infants

OBJECTIVE

To determine if physical activity delivered by an infant's mother would be as effective in promoting bone mineral acquisition in preterm very low birth weight (VLBW) infants as the same intervention administered by a trained therapist.

PATIENTS AND METHODS

Preterm VLBW infants were randomized to receive daily physical activity administered by the infant's mother (MOM, n=11) or a trained therapist (OT, n=11), or control (n=11). Physical activity consisted of range of motion movements against passive resistance to all extremities for 5 to 10 min daily. All infants were fed mother's milk with fortification to 24 kcal oz(-1). Dual energy x-ray of the forearm bone area (BA, cm(2)), mineral content (BMC, g), and density (BMD, g/cm(2)) and measurement of bone formation (bone-specific alkaline phosphatase, BAP) and resorption (urine pyridinium crosslinks of collagen, Pyd) were obtained at study entry and at 2.0 kg of body weight.

RESULT

Forearm BA and BMC gains were greater in MOM and OT infants compared to the control infants despite similar postnatal growth rate and nutrient intake. Serum BAP levels decreased in controls but remained unchanged in MOM and OT infants. Urine Pyd levels were similar at baseline to 2.0 kg for all groups. These findings suggest greater bone growth and mineral acquisition in MOM and OT infants than control infants.

CONCLUSION

This study demonstrates that a physical activity program administered by the infant's own mother is as equally effective as therapist-administered physical activity in promoting greater bone growth and mineral acquisition in preterm VLBW infants.