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

Role of fibroblast growth factor-23 as an early marker of metabolic bone disease of prematurity

PURPOSE

Metabolic bone disease of prematurity (MBDP) remains a significant cause of morbidity in extremely premature newborns. In high-risk patients, suspected diagnosis and subsequent treatment modifications, with limitations in terms of sensitivity and specificity, rely on low phosphorus levels and/or high levels of alkaline phosphatase (ALP). We investigated the potential of fibroblast growth factor-23 (FGF23) as an early marker for MBDP when measured at 3-4 weeks of life in at-risk patients.

METHODS

A single-center prospective observational non-interventional study including preterm newborns of both sexes, with a gestational age of less than 32 weeks and/or a birth weight of less than 1500 g. In the standard biochemical screening for MBDP performed between 3 and 4 weeks of life within a nutritional profile, the determination of FGF23 was included along with other clinical and metabolic studies. The study was conducted at Marqués de Valdecilla University Hospital in Santander, Spain, from April 2020 to March 2021. Participants provided informed consent. Biochemical analyses were conducted using various platforms, and follow-up evaluations were performed at the discretion of neonatologists. Patients at high risk for MBDP received modifications in treatment accordingly. The sample was descriptively analyzed, presenting measures of central tendency and dispersion for continuous variables, and absolute numbers/percentages for categorical ones. Tests used included t-tests, Mann‒Whitney U tests, chi-square tests, logistic regressions, Pearson correlation, and ROC curve analysis (IBM SPSS Statistics version 19). Significance level: P < 0.05.

RESULTS

In the study involving 25 at-risk premature newborns, it was found that 20% (n = 5) were diagnosed with MBDP. Three of these patients (60%) were identified as high-risk based on standard biochemical evaluation at 3-4 weeks of age, while the other two patients (40%) were diagnosed in subsequent weeks. However, in all 5 patients, measurement of FGF23 levels would allow for early identification and optimization of treatment before other markers become altered. Low levels of FGF23 at 3-4 weeks, even with normal phosphorus and ALP levels, indicate the need for modifications in nutritional supplementation.

CONCLUSIONS

MBDP remains a significant concern in extremely premature newborns. Current diagnostic methods rely on limited biochemical markers. Early detection of low FGF23 levels enables timely interventions, potentially averting demineralization.

Biomarkers and Biochemical Indicators to Evaluate Bone Metabolism in Preterm Neonates

The purpose of the present study was to evaluate the concentrations of some bone turnover markers in preterm neonates with uncomplicated clinical course in the first month of life. Samples from 13 preterm neonates were collected at three different times: at birth (T0) from umbilical cord blood (UCB); and at 15 (T1) and 30 (T2) days of life from peripheral blood (PB). The concentrations of calcium (Ca), phosphate (P), total alkaline phosphatase (ALP), Collagen Type 1 Amino-terminal Propeptide (PINP), osteocalcin (OC), Collagen Type 1 Carboxyl-Terminal Telopeptide (CTX) and Leptin were assessed. A statistically significant difference for ALP concentration at birth versus T1 and T2 was found. An evident increase in the median concentrations of CTX, OC and PINP from T0 to T2 were observed. A significant difference was also found for Leptin concentration at T0 compared to T1. In preterm infants, in the absence of acute or chronic medical conditions and without risk factors for metabolic bone disease (MBD) of prematurity, there is a significant increase in bone turnover markers during the first month of life. The knowledge of the variations in these markers in the first weeks of life, integrated by the variations in the biochemical indicators of bone metabolism, could help in recognizing any conditions at risk of developing bone diseases.

Neurodevelopment Outcomes in Very-Low-Birth-Weight Infants with Metabolic Bone Disease at 2 Years of Age

Metabolic bone disease (MBD) predominantly affects preterm infants, particularly very-low-birth-weight (VLBW) infants weighing <1500 g. However, there are limited reports on MBD and neurodevelopmental outcomes. This study aimed to analyze the risk factors for MBD and understand its impact on neurodevelopmental outcomes at 2 years of corrected age. Overall, 749 VLBW infants weighing <1350 g at birth were enrolled. Exclusion criteria were major congenital abnormalities, chromosomal abnormalities, and loss of follow-up on the Bayley Scales of Infant Development, Third Edition (BSID-III) test at 24 months of corrected age. Infants were retrospectively assessed by a trained case manager using the BSID-III test at 6, 12, and 24 months old. Infants were categorized as with or without MBD according to radiographic signs. Of those enrolled, 97 VLBW infants were diagnosed with MBD, compared to 362 VLBW infants without MBD. The proportion of infants that completed three follow-ups was 86%. At the assessment at 2 years of age, infants with MBD had lower and more significant differences in motor, language, and cognitive composites. MBD is associated with poor neurodevelopmental outcomes in cognitive, motor, and language composites for VLBW infants at 24 months of corrected age.

Asymptomatic Infant Rib Fractures Are Primarily Non-abuse-Related and Should Not Be Used to Assess Physical Child Abuse

Finding infant rib fractures was for many years an almost undisputed proof that physical child abuse took place. Yet, these rib fractures are virtually always occult and asymptomatic and are only identified when looked for, usually with X-rays, from physical child abuse accusations related to, e.g., suspicion of the shaken baby syndrome. In a recent systematic literature review (searched in Cochran, Embase, PubMed and Sociological Abstracts), Güvensel questioned the diagnostic accuracy of rib fractures to be caused by abuse, due to lack of sufficient scientific evidence. Further, there is currently a world-wide disagreement between physicians considering themselves child abuse specialized, and physicians that explore non-abuse-related symptoms that may mimic physical abuse, which, it is hoped, will significantly reduce current unjustified child abuse diagnoses. In an attempt to help resolving this disagreement, we hypothesize that the probability of physical child abuse-related infant rib fractures is significantly lower than the probability of all other possible non-abuse-related causes of occult asymptomatic infant rib fractures, e.g., from birth trauma, prematurity, osteogenesis imperfecta, hypermobile Ehlers-Danlos Syndrome, severe chronic placental pathology (e.g., massive perivillous fibrin depositions and severe chronic histiocytic intervillositis), and vitamin-D deficiency. As method, we attempted to assess the incidence of these various causes of infant rib fractures, in the Netherlands and the USA. The results are that the estimated Dutch and USA physical abuse-related infant rib fracture incidences are at least about 250 and 45 times lower than the sum of all the non-abuse-related estimates. Because these latter rib fractures are occult and asymptomatic, it is likely that (many) more could be out there. In conclusion, occult asymptomatic rib fractures develop perinatally, virtually always as birth trauma, in infants with sufficiently weak bones due to vitamin D deficiency, transmitted by their vitamin D deficient pregnant mothers. This group also includes cortical rib cracks due to deformation forces, with an estimated 186/100,000 incidence. And, despite obvious uncertainties in all estimated incidences, we provided strong evidence that our hypothesis has relevance, implying that the abundant occult asymptomatic rib fractures, when found in infants, should not be used to assess potential physical child abuse.

Calcium and Phosphorus: All You Need to Know but Were Afraid to Ask

Inadequate intake of calcium and phosphorus during the perinatal period can result in metabolic bone disease (MBD), characterized by decreased bone mass, altered bone mineralization, and increased risk for fractures. Preterm neonates have higher risk of developing MBD. Treating MBD involves ensuring adequate calcium and phosphorus intake, early fortification, and vitamin D supplementation. Health care providers should closely monitor nutrient intake, postnatal growth, and screening of preterm neonates at risk for MBD. This review summarizes the critical roles of calcium and phosphorus in regulating bone physiology, how they regulate bone formation and resorption, and their influence on overall bone health.

Effects of early introduction of solid foods on nutrient intake in preterm infants during their 1st year of life: a secondary outcome analysis of a prospective, randomized intervention study

Very low birth weight (VLBW) infants have higher nutritional needs even after hospital discharge. However, data concerning current nutrient intakes at different time points after the introduction of solid foods and whether dietary reference values are being met are scarce. To adress this issue, this secondary analysis of a prospective, two-arm interventional study in 177 VLBW infants 21 investigates dietary intake comparing early and late (early: 10-12 weeks corrected for gestational age, late: 16-18 weeks corrected for gestational age) introduction of standardized complementary food during the first year of life. Nutritional intake was assessed using self-reported monthly 3-day dietary records from 3 until 12 months, corrected for gestational age. The time point of the introduction of solid foods did not influence nutrient intake, but the early introduction of solids tended toward a higher proportional intake of protein and carbohydrates and a lower intake of fat as a percentage of total energy) during the 1st year of life, corrected for gestational age. The results of this study indicate that this standardized feeding concept was sufficient for zinc, calcium, and phosphorus intake. However, dietary iron and vitamin D intakes did not meet the recommendations. Thus, prolonged iron supplementation should be considered beyond the introduction of meat and vitamin D supplementation at least until 12 months, corrected for gestational age.

Trial registration number

ClinicalTrials.gov: NCT01809548.

Risk factors for metabolic bone disease of prematurity: A meta-analysis

Objective

To investigate the risk factors for metabolic bone disease of prematurity (MBDP), and to provide a reference for the prevention of MBDP.

Methods

The databases including China Biomedical Literature Service System, China National Knowledge Infrastructure, Wanfang Data, and Weipu Periodical Database, PubMed, Web of Science, Embase, Cochrane Library and other databases were searched for studies on the risk factors for MBDP published up to June 18, 2021. RevMan 5.3 and Stata 14.1 software were used to perform a Meta analysis.

Results

A total of 15 articles were included, including 13 case-control studies, 1 current investigation, and 1 retrospective cohort study. There were 1,435 cases in the case group and 2,057 cases in the control group, with a total sample size of 3,492 cases. Meta analysis showed that risk factors for MBDP include birth weight <1000g (OR = 6.62, 95%CI: 2.28–19.25), gestational age <32 weeks (OR = 2.73, 95%CI: 1.07–6.95), septicemia (OR = 2.53, 95%CI: 1.69–3.79), parenteral nutrition time (OR = 4.04, 95%CI: 1.72–9.49), cholestasis (OR = 3.50, 95%CI: 1.49–8.23), intrauterine growth retardation (OR = 6.89, 95%CI: 3.81–12.44), while the birth weight(OR = 0.44, 95%CI: 0.21–0.90) and gestational age (OR = 0.57, 95%CI: 0.44–0.73)are the protective factors of MBDP.

Conclusion

Factors like birth weight <1000g, gestational age <32 weeks, septicemia, parenteral nutrition time, cholestasis, and intrauterine growth retardation may increase the risk of metabolic bone disease of prematurity.

Vitamin D, bone density, and nephrocalcinosis in preterm infants: a prospective study

BACKGROUND

Vitamin D (VitD) supplementation is recommended by the American Academy of Pediatrics (AAP) for preterm infants to improve bone density. Complications of VitD supplementation include hypercalciuria and nephrocalcinosis (NC). NC has been reported in 7-64% infants < 32 weeks gestational age (GA) or < 1500 g birth weight (BW). The relationships between VitD supplementation, serum 25-hydroxy VitD levels, bone density, hypercalciuria and development of NC in preterm infants are not well established.

METHODS

Prospective, observational cohort study of 56 infants with GA ≤ 32 weeks or BW ≤ 1800 g. Demographics, dietary intakes, serum 25-hydroxy VitD levels and weekly urinalyses were collected until 40 weeks corrected GA or discharge. Bone mineral density (BMD) and content (BMC) were assessed using dual-energy X-ray absorptiometry (DEXA) scan. NC was identified by kidney ultrasound.

RESULTS

56 infants received on average 447 IU/day of VitD with average serum 25-hydoxy VitD level 39.6 ng/mL. DEXA scan showed average BMD 0.13 g/cm² and BMC 35.8 g. 23/56 (41%) infants were diagnosed with NC. Infants with NC had lower GA (p < 0.01) and BW (p < 0.01) and increased presence of calcium oxalate crystals (78% vs. 36%) (p = 0.002). There were no differences in VitD intake, urine calcium/creatinine ratios or BMD and BMC in infants with versus without NC.

CONCLUSIONS

VitD supplementation per AAP guidelines resulted in acceptable serum 25-hydroxyVitD levels, but no improvement in BMD or BMC compared to previously reported values. However, infants receiving recommended amounts born at earlier GA and lower BW are at increased risk of NC. VitD supplementation and serum levels should be closely monitored in this high-risk population. A higher resolution version of the Graphical abstract is available as Supplementary information.

Sex-Specific Effects of Nutritional Supplements for Infants Born Early or Small: An Individual Participant Data Meta-Analysis (ESSENCE IPD-MA) II: Growth

Neonatal nutritional supplements may improve early growth for infants born small, but effects on long-term growth are unclear and may differ by sex. We assessed the effects of early macronutrient supplements on later growth. We searched databases and clinical trials registers from inception to April 2019. Participant-level data from randomised trials were included if the intention was to increase macronutrient intake to improve growth or development of infants born preterm or small-for-gestational-age. Co-primary outcomes were cognitive impairment and metabolic risk. Supplementation did not alter BMI in childhood (kg/m²: adjusted mean difference (aMD) -0.11[95% CI -0.47, 0.25], p = 0.54; 3 trials, n = 333). Supplementation increased length (cm: aMD 0.37[0.01, 0.72], p = 0.04; 18 trials, n = 2008) and bone mineral content (g: aMD 10.22[0.52, 19.92], p = 0.04; 6 trials, n = 313) in infancy, but not at older ages. There were no differences between supplemented and unsupplemented groups for other outcomes. In subgroup analysis, supplementation increased the height z-score in male toddlers (aMD 0.20[0.02, 0.37], p = 0.03; 10 trials, n = 595) but not in females, and no significant sex interaction was observed (p = 0.21). Macronutrient supplementation for infants born small may not alter BMI in childhood. Supplementation increased growth in infancy, but these effects did not persist in later life. The effects did not differ between boys and girls.

Hormonal regulation of biomineralization

Biomineralization is the process by which organisms produce mineralized tissues. This crucial process makes possible the rigidity and flexibility that the skeleton needs for ambulation and protection of vital organs, and the hardness that teeth require to tear and grind food. The skeleton also serves as a source of mineral in times of short supply, and the intestines absorb and the kidneys reclaim or excrete minerals as needed. This Review focuses on physiological and pathological aspects of the hormonal regulation of biomineralization. We discuss the roles of calcium and inorganic phosphate, dietary intake of minerals and the delicate balance between activators and inhibitors of mineralization. We also highlight the importance of tight regulation of serum concentrations of calcium and phosphate, and the major regulators of biomineralization: parathyroid hormone (PTH), the vitamin D system, vitamin K, fibroblast growth factor 23 (FGF23) and phosphatase enzymes. Finally, we summarize how developmental stresses in the fetus and neonate, and in the mother during pregnancy and lactation, invoke alternative hormonal regulatory pathways to control mineral delivery, skeletal metabolism and biomineralization.

Update on Calcium and Phosphorus Requirements of Preterm Infants and Recommendations for Enteral Mineral Intake

Background: With current Ca and P recommendations for enteral nutrition, preterm infants, especially VLBW, fail to achieve a bone mineral content (BMC) equivalent to term infants. During the first 3 years, most notably in light at term equivalent age (<−2 Z score) VLBW infants’ BMC does not catch up. In adults born preterm with VLBW or SGA, lower adult bone mass, lower peak bone mass, and higher frequency of osteopenia/osteoporosis have been found, implying an increased risk for future bone fractures. The aim of the present narrative review was to provide recommendation for enteral mineral intake for improving bone mineral accretion. Methods: Current preterm infant mineral recommendations together with fetal and preterm infant physiology of mineral accretion were reviewed to provide recommendations for improving bone mineral accretion. Results: Current Ca and P recommendations systematically underestimate the needs, especially for Ca. Conclusion: Higher enteral fortifier/formula mineral content or individual supplementation is required. Higher general mineral intake (especially Ca) will most likely improve bone mineralization in preterm infants and possibly the long-term bone health. However, the nephrocalcinosis risk may increase in infants with high Ca absorption. Therefore, individual additional enteral Ca and/or P supplementations are recommended to improve current fortifier/formula mineral intake.

Overview of Important Micronutrients Supplementation in Preterm Infants after Discharge: A Call for Consensus

Preterm infants have a lower level of nutrient body stores and immature body systems, resulting in a higher risk of malnutrition. Imbalanced complementary feeding could lead to further risk of nutritional deficits and excesses. However, evidence on their nutritional requirements following hospital discharge is limited. When planning complementary feeding, appropriate micronutrient intake should be considered for their critical role in supporting various body functions. This narrative review summarizes the need for iron, zinc, vitamin D, calcium, phosphate and long-chain polyunsaturated fatty acids (LCPUFAs) supplementation in preterm infants during complementary feeding. Regarding iron and vitamin D, the scientific community is reaching an agreement on supplementation in some categories of prematures. On the contrary, there is still not enough evidence to detail possible recommendations for LCPUFAs, zinc, calcium and phosphorus supplementation. However, these micronutrients are paramount for preterms' health: LCPUFAs can promote retinal and brain development while calcium and phosphorus supplementation is essential to prevent preterms' metabolic bone disease (MBD). Waiting for a consensus on these micronutrients, it is clear how the knowledge of the heterogeneity of the prematures population can help adjust the nutritional planning regarding the growth rate, comorbidities and comprehensive clinical history of the preterm infant.

Modified Serum ALP Values and Timing of Apparition of Knee Epiphyseal Ossification Centers in Preterm Infants with Cholestasis and Risk of Concomitant Metabolic Bone Disease of Prematurity

The usefulness of serum alkaline phosphatase (ALP) and phosphorous in screening and monitoring of metabolic bone disease of prematurity (MBDP) still has some limitations, especially in preterm infants with concomitant conditions such as cholestasis. We aimed to assess a modification of serum ALP (M-ALP) as a biomarker for MBDP in preterm infants, and the use of ultrasound monitoring for the apparition of knee ossification centers as marker of bone mineralization. Biochemical and clinical registers were taken from 94 preterm newborns <32 weeks. A significant correlation existed between serum ALP and direct bilirubin (DB), expressed by the regression equation: M-ALP (IU/L) = 302.1 + 96.9 (DB (mg/dL)). The ratio ALP/M-ALP > 1 was demonstrated to be more specific (87.5%) in the diagnosis of MBDP than the cut-off value of serum ALP > 500 IU/L (62.5%). ALP/M-ALP > 1 showed 100% sensitivity and specificity for the diagnosis of MBDP, and a good correlation with specific bone ALP (B-ALP). Patients with the knee nucleus by post-menstrual week 37 had lower B-ALP compared to patients with no nucleus, and no patients with MBDP presented the nucleus by the 40th week. In the absence of reliable specific B-ALP, reinterpreting serum ALP values by M-ALP plus monitoring of knee ossification centers contribute to better management of MBDP in preterm infants with cholestasis.

Metabolic Bone Disease in Premature Neonates: An Unmet Challenge

Metabolic bone disease (MBD) is an important cause of morbidity in premature, very low birth weight (VLBW) and sick infants and, if left undiagnosed, may lead to structural deformities and spontaneous fractures. MBD is defined as impaired bone mineralization in a neonate with lower than expected bone mineral levels in either a fetus or a neonate of comparable gestational age and/or weight, coupled with biochemical abnormalities with or without accompanying radiological manifestations. MBD has been reported to occur in 16% to 40% of extremely low birth weight neonates and presents by 6-16 weeks after birth. Insufficient calcium and phosphorous stores during the phase of accelerated growth predispose to MBD in neonates along with the use of some medications such as caffeine or steroids, prolonged parenteral nutrition and chronic immobilization. Enhanced physical activity in preterm infants facilitates bone mineralization and weight gain. Biochemical abnormalities tend to worsen significantly, as the severity of disease progresses. These abnormalities may include hypocalcemia, hypophosphatemia, hyperphosphatasia and secondary hyperparathyroidism. In addition, urinary phosphate wasting and hypovitaminosis D can be additional complications. Conversely, biochemical abnormalities may not be accompanied by rachitic changes. Newer diagnostic modalities include non-invasive bone densitometry by quantitative ultrasound over the mid-tibial shaft. The management of MBD includes adequate calcium, phosphorous and vitamin D supplementation, along with optimum nutrition and physical activity. Similarly, preventive strategies for MBD should target nutritional enhancement in combination with enhanced physical activity. MBD usually results in preventable morbidity in preterm and VLBW neonates. Treatment consists of optimum nutritional supplementation and enhanced physical activity.

Hypophosphatemia as an Early Metabolic Bone Disease Marker in Extremely Low-Birth-Weight Infants After Prolonged Parenteral Nutrition Exposure

BACKGROUND

Early metabolic bone disease (MBD) detection is important in preterm infants to decrease long-term consequence. We aim to explore the early MBD biochemical marker in extremely low-birth-weight (ELBW) infants.

METHODS

Retrospective cohort study of 95 preterm infants born in a tertiary care-level neonatal intensive care unit between January 2015 and June 2018, with birth weight <1000 g. Thirty-five infants were "nothing by mouth" for >14 days and categorized as the high-risk group; the remaining 60 were categorized as the control group. Mineral intake in the first 14 days and the trend of serum calcium (Ca), phosphorus (P), and alkaline phosphatase (ALP) levels were compared in both groups.

RESULTS

The Ca and P supplementation in the first 2 weeks of life were inadequate in both groups. Compared with the control group, significantly lower serum P (mg/dL) levels were noted in the high-risk group on weeks 2 (3.65 ± 1.2 vs 4.67 ± 1.45; P < .001), 4 (3.21 ± 0.95 vs 5.83 ± 1.18; P < .0001), and 6 (3.94 ± 1.1 vs 6.22 ± 0.78; P <.0001). There was no significant difference in the serum Ca level, and significantly higher ALP (U/L) levels were found up until 2 months of life in the high-risk group (458.36 ± 189.02 vs 335.7 ± 111.51; P < .014).

CONCLUSION

Hypophosphatemia developed as early as 2 weeks old in high-risk preterm infants because of inadequate supplementation. Neither the serum Ca or ALP levels were affected. Thus, the routine monitoring of serum P level should be started 2 weeks after birth for early MBD detection in extremely ELBW infants.

Do preterm bones still break? Incidence of rib fracture and osteopenia of prematurity in very low birth weight infants

AIM

Extremely premature babies are at risk of osteopenia of prematurity (OOP) as bone mineralisation in utero increases exponentially after 24 weeks gestation. Our aim was to assess the bone health of very low birth weight (VLBW) infants. We wanted to establish the incidences of OOP and rib fracture. We also looked at which biochemical markers best predicted OOP. Bone health in this vulnerable population is an important aspect of management which should not be overlooked.

METHODS

This was an observational study which included all VLBW infants, born in a national maternity hospital, over a 5-year period. All X-rays performed on these infants were reviewed. Data were also collected on biochemical markers associated with bone health. The medical records of infants with rib fractures were reviewed looking for causes of bone fragility.

RESULTS

Of the 609 VLBW infants included in the study, only two cases of definitive rib fractures were found. This represents a rib fracture incidence of 3 per 1000. Thirty-nine percent of VLBW babies showed radiological evidence suggestive of OOP.

CONCLUSION

Our findings show a lower rate of rib fracture in preterm infants compared to previous evidence. We also showed that these fractures were not evident on the final X-ray prior to discharge. This implies that when an ex-preterm infant presents to the emergency department with a rib fracture there should be an even higher suspicion for non-accidental injury than previously thought.

The Effect of Daily Exercise Program on Bone Mineral Density and Cortisol Level in Preterm Infants with Very Low Birth Weight: A Randomized Controlled Trial

PURPOSE

This randomized controlled double-blinded experimental study was carried out to determine the effects of the daily exercise program on bone mineral density and cortisol level in preterm infants with VLBW matched for birth weight, gestation week, and gender.

DESIGN AND METHODS

The study was carried out with preterm infants (n = 24) hospitalized in the NICU of a tertiary hospital. Ethical committee approval, institutional permission, parental written consent were obtained. A daily exercise program was implemented in preterm infants in the exercise group for 30 days, once a day, and continuing for 7-10 min. Before and after the study the following were evaluated in preterm infants in the exercise and control group: anthropometric measurements, tibia speed of sound (SOS) for bone mineral density, serum cortisol levels.

RESULTS

Serum cortisol levels (p = 0.05) were decreased, bone SOS values in the exercise group were increased (p = 0.009), after the study. The difference between pre-, post-study bone SOS and serum cortisol values of infants in the exercise group were high (p > 0.05). Percentage increases in anthropometric values in the exercise group were higher than the control group after the study (for all; p > 0.05).

CONCLUSIONS

The daily exercise program has positive effect on bone SOS and serum cortisol values in preterm infants. Neonatal nurses can implement the daily exercise program in clinical practice. Trial registration numberClinicaltrials.govNCT03773679.

Association of Protein and Vitamin D Intake With Biochemical Markers in Premature Osteopenic Infants: A Case-Control Study

Osteopenia in preterm infants (OP) remains an important challenge and is largely dependent on nutritional post-natal intake of factors influencing bone mineralization. We conducted a prospective case-control study to evaluate the importance of protein and vitamin D intake in OP among neonates with birth weight <1,250 g. Simultaneous serum parathyroid hormone (PTH), alkaline phosphatase (ALP), calcium (Ca), phosphorus (P), vitamin D and protein levels were measured during the first six post-natal weeks. At 6 weeks of age, OP was evaluated using wrist radiographs. Comparisons were analyzed using multivariate linear regression, receiver operating characteristic curves, χ2 and Wilcoxon Rank Sum. Of the 26 premature infants enrolled, 13 developed radiographic OP. Daily protein intake (coef = -0.40, p = 0.001) and vitamin D concentrations (21 ± 5.7 ng/ml) were significantly lower in the OP group compared to non-OP subjects. ALP concentration exceeding 619 IU/L, sensitivity of 76.9% and specificity of 75%, was predictive of OP at 6 weeks post-natally. PTH levels were higher at 6 weeks in OP subjects (193 ± 102.5 pg/ml, p < 0.001) compared to non-OP subjects. The findings in this study support the role of vitamin D and protein intake in the development of OP in VLBW infants and inform future practice and research on best practices for OP management.

Prematurity Does Not Increase Early Childhood Fracture Risk

OBJECTIVE

To evaluate the impact of prematurity on fracture by age 5, controlling for medications and comorbidities of prematurity.

STUDY DESIGN

We performed a retrospective cohort study of infants born in Military Treatment Facilities in 2009-2010 with ≥5 years of follow-up care. Gestational age, low birth weight, comorbidities of prematurity (osteopenia, necrotizing enterocolitis, chronic lung disease, and cholestasis) and fractures were identified by International Classification of Disease, 9th Edition, codes. Pharmaceutical records identified treatment with caffeine, diuretics, postnatal corticosteroids, and antacids. Poisson regression analysis determined fracture rate by 5 years of life.

RESULTS

There were 65 938 infants born in 2009-2010 who received care in the military health system for ≥5 years, including 3589 born preterm; 165 born at ≤28^6/7 weeks of gestation, 380 born at 29-31^6/7 weeks of gestation, and 3044 born at 32-36^6/7 weeks of gestation. Preterm birth at any gestational age was not associated with fracture rate in adjusted models. The fracture rate was increased with cholestasis, proton pump inhibitor exposure, and male sex.

CONCLUSIONS

Prematurity was not associated with fracture rate. Neonatal cholestasis and proton pump inhibitor treatment were associated with increased fractures by age 5.

Metabolic Bone Disease of Prematurity: Diagnosis and Management

Metabolic Bone Disease (MBD) of prematurity is a multifactorial disorder commonly observed in very low birth weight (VLBW, <1,500 g) newborns, with a greater incidence in those extremely low birth weight (ELBW, <1,000 g). MBD is characterized by biochemical and radiological findings related to bone demineralization. Several antenatal and postnatal risk factors have been associated to MBD of prematurity, although the main pathogenetic mechanism is represented by the reduced placental transfer of calcium and phosphate related to preterm birth. The diagnosis of MBD of prematurity requires the assessment of several biochemical markers, radiological, and ultrasonographic findings. However, the best approach is the prevention of the symptomatic disease, based on the screening of subjects exposed to the risks of developing MBD. Regarding the subjects who need to be screened, there is a substantial agreement on the potential risk factors for MBD. On the contrary, different recommendations exist on the diagnosis, management and treatment of this disorder of bone metabolism. This review was aimed at: (1) identifying the subjects at risk for MBD of prematurity; (2) indicating the biochemical findings to take in consideration for the prevention of MBD of prematurity; (3) suggesting practical recommendations on nutritional intake and supplementation in these subjects. We searched for papers which report the current recommendations for biochemical assessment of MBD of prematurity and for its prevention and treatment. The majority of the authors suggest that MBD of prematurity is a disease which tends to normalize overtime, thus it is not mandatory to mimic the rate of mineral fetal accretion through parenteral or enteral supplementation. The optimization of total parenteral nutrition (TPN) and the early achievement of a full enteral feeding are important goals for the prevention and management of MBD of prematurity.

Acetylcholinesterase activity and bone biochemical markers in premature and full-term neonates

Background Almost 30% of the premature infants have low body weight and bone mineral density due to prematurity. There is no consensus of screening premature neonates for metabolic bone disease; therefore, it is important to investigate the use of bone biochemical parameters. Latest studies involved the activity of acetylcholinesterase as a mediator in bone remodeling. It is hypothesized that there is a possible correlation of bone biochemical biomarkers and acetylcholinesterase (AChE) activity in premature infants. Methods We studied 50 neonates (26 preterm with gestational age <32 weeks, 24 full-term). Clinical data (sex, gestational week) and anthropometric parameters (body weight) were recorded. We directly measured the bone biochemical markers in serum such as alkaline phosphatase (ALP), calcium (Ca), phosphorus (P), magnesium (Mg) and parathyroid hormone (PTH). In addition, we measured the AChE activity. Results ALP and parathyroid hormone levels were higher, but Ca, P and AChE were lower in premature neonates group compared with full-term ones. There is a significant positive correlation of gestational age with body weight, Ca and AChE. A significant negative correlation was observed for ALP and PTH with gestational age. Conclusions We found a gestational age-related increase of AChE activity. There were significant relationships between AChE activity with P and PTH.

Metabolic bone disease risk factors strongly contributing to long bone and rib fractures during early infancy: A population register study

Background

The aim of this study was to assess the incidence of fractures in infancy, overall and by type of fracture, its association with accidents, metabolic bone disease risk factors, and abuse diagnosis.

Methods

The design was a population-based register study in Sweden. Participants: Children born 1997–2014, 0–1 years of age diagnosed with fracture-diagnosis according to International Classification of Diseases (ICD10) were retrieved from the National Patient Register and linked to the Swedish Medical Birth Register and the Death Cause Register. Main outcome measures were fractures of the skull, long bone, clavicle and ribs, categorized by age (younger or older than 6 months), and accident or not.

Findings

The incidence of fractures during infancy was 251 per 100 000 infants (n = 4663). Major fracture localisations were long bone (44·9%), skull (31·7%), and clavicle (18·6%), while rib fractures were few (1·4%). Fall accidents were reported among 71·4%. One-third occurred during the first 6 months. Metabolic bone disease risk factors, such as maternal obesity, preterm birth, vitamin D deficiency, rickets, and calcium metabolic disturbances, had increased odds of fractures of long bones and ribs in early infancy (0–6 months): birth 32–36 weeks and long bone fracture [AOR 2·13 (95%CI 1·67–2·93)] and rib fracture [AOR 4·24 (95%CI 1·40–12·8)]. Diagnosis of vitamin D deficiency/rickets/disorders of calcium metabolism had increased odds of long bone fracture [AOR 49·5 (95%CI 18·3–134)] and rib fracture [AOR 617 (95%CI 162–2506)]. Fractures without a reported accident had higher odds of metabolic risk factors than those with reported accidents. Abuse diagnosis was registered in 105 infants, with overrepresentation of preterm births, multiple births and small-for-gestational age.

Interpretation

Metabolic bone disease risk factors are strongly associated with fractures of long bone and ribs in early infancy. Fracture cases with abuse diagnosis had a metabolic bone risk factor profile.

Risk factors analysis and prevention of metabolic bone disease of prematurity

The present study aims to analyze the risk factors for metabolic bone disease (MBD) of prematurity.A total of 238 preterm infants who were born at <34 weeks of gestation and were hospitalized for at least 6 weeks in the Department of Neonatology, Fujian Maternity and Children Hospital between January 1, 2011 and November 30, 2015 were enrolled in the study. Sixteen preterm infants diagnosed with MBD were selected as the case group, and 32 non-MBD preterm infants were matched 2:1 at admission into the study. The 2 groups were compared to examine the differences in maternal obstetric conditions, conditions during parturition, neonatal conditions, and neonatal diseases and treatments. The risk factors for MBD of prematurity were analyzed using t tests, χ tests, and a logistic regression model.The mean gestational age and birth weight of the case group were significantly lower (P < .05) than those of the control group. Compared with the control group, the case group had a significantly higher ratios of small-for-gestational-age infants, antenatal maternal corticosteroids use, sedative use, ventilator use, aminophylline use, diuretic use, liver function impairment, vitamin D (VitD) supplementation at more than 14 days of age, achievement of total enteral nutrition (TEN) beyond 28 days of age, and feeding intolerance.Logistic regression analysis showed that birth at <30 weeks of gestation, VitD supplementation at >14 days of age, and achievement of TEN beyond 28 days of age were independent risk factors for MBD (P < .05).Level of Evidence: IV.

Elemental formula associated hypophosphataemic rickets

OBJECTIVES

Hypophosphataemic rickets (HR) is usually secondary to renal phosphate wasting but may occur secondary to reduced intake or absorption of phosphate. We describe a series of cases of HR associated with the use of Neocate^®, an amino-acid based formula (AAF).

METHODS

A retrospective review of cases with HR associated with AAF use presenting to centres across the United Kingdom.

RESULTS

10 cases were identified, over a 9 month period, all associated with Neocate^® use. The age at presentation was 5 months to 3 years. The majority (8/10) were born prematurely. Gastro oesophageal reflux disease (6/10) was the most frequent indication for AAF use. Radiologically apparent rickets was observed after a median of 8 months (range 3-15 months) of exclusive Neocate^® feed. The majority (7/10) were diagnosed on the basis of incidental findings on radiographs: rickets (6/10) or fracture with osteopenia (5/10). All patients had typical biochemical features of HR with low serum phosphate, high alkaline phosphatase, normal serum calcium and 25 hydroxyvitamin D. However, in all cases the tubular reabsorption of phosphate (TRP) was ≥96%. Phosphate supplementation resulted in normalisation of serum phosphate within 1-16 weeks, and levels remained normal only after Neocate^® cessation. In patients with sufficient follow up duration (4/10), normalisation of phosphate and radiological healing of rickets was noted after 6 months (range: 6-8 months) following discontinuation of Neocate^®.

CONCLUSION

The presence of a normal TRP and resolution of hypophosphataemia and rickets following discontinuation of Neocate^® indicates this is a reversible cause likely mediated by poor phosphate absorption. Close biochemical surveillance is recommended for children on Neocate^®, especially in those with gastrointestinal co-morbidities, with consideration of a change in feed or phosphate supplementation in affected children.

Could low birth weight and preterm birth be associated with significant burden of hip osteoarthritis? A systematic review

BACKGROUND

Approaches for the prevention and treatment of hip osteoarthritis (OA) remain limited. There are recent data suggesting that low birth weight (LBW) and preterm birth may be risk factors for hip osteoarthritis. This has the potential to change the current paradigm of hip osteoarthritis prevention by targeting early life factors. The aim of this review was to examine the available evidence for an association of LBW and preterm birth with hip OA. The potential cost implications associated with total hip arthroplasty were also evaluated.

METHODS

Ovid Medline, EMBASE, and Cinahl were searched up until August 2017 using MeSH terms and key words. Methodological quality was evaluated using the National Heart Lung and Blood Institute (NHLBI) quality assessment tool. Qualitative evidence synthesis was performed to summarise the results. Bradford Hill's criteria for causation including the temporal relationship, consistency, strength of the association, specificity, dose-response relationship, and analogy were used to assess the evidence for causation. Economic modelling was used to calculate the potential economic burden associated with LBW or preterm birth related total hip arthroplasty using Australian data from 2012 to 2015.

RESULTS

Five studies, ranging from high to low quality, were included. Hip bone shape abnormalities examined included developmental hip dysplasia and immature hip, and hip osteoarthritis included osteophytes and total hip arthroplasty. A causal link between low birth weight or preterm birth and hip osteoarthritis was found. Of the 30,477 total hip arthroplasties performed for hip osteoarthritis in Australia in 2015, 5791 were estimated to be born preterm and 5273 with low birth weight. This equated to a potential total hip arthroplasty cost of AU$145,136,082 and AU$132,150,222 for these subgroups, respectively.

CONCLUSION

Available data suggest that low birth weight and preterm birth are associated with hip bone shape abnormalities and hip osteoarthritis requiring total hip arthroplasty, with a substantial associated financial burden. Given the current lack of effective treatment and prevention strategies for hip osteoarthritis, this offers a new avenue for reducing the future burden of hip osteoarthritis.

Vitamin D in pediatric age: consensus of the Italian Pediatric Society and the Italian Society of Preventive and Social Pediatrics, jointly with the Italian Federation of Pediatricians

Vitamin D plays a pivotal role in the regulation of calcium-phosphorus metabolism, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur.Besides its historical skeletal functions, in the last years it has been demonstrated that vitamin D directly or indirectly regulates up to 1250 genes, playing so-called extraskeletal actions. Indeed, recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious, allergic and autoimmune diseases. Thus, vitamin D deficiency may affect not only musculoskeletal health but also a potentially wide range of acute and chronic conditions. At present, the prevalence of vitamin D deficiency is high in Italian children and adolescents, and national recommendations on vitamin D supplementation during pediatric age are lacking. An expert panel of the Italian Society of Preventive and Social Pediatrics reviewed available literature focusing on randomized controlled trials of vitamin D supplementation to provide a practical approach to vitamin D supplementation for infants, children and adolescents.

Impact of Early Versus Late Diuretic Exposure on Metabolic Bone Disease and Growth in Premature Neonates

OBJECTIVES

This study aimed to determine whether there are differences in the incidence of metabolic bone disease (MBD) between preterm neonates first exposed to diuretics prior to 2 weeks of life versus those exposed after 2 weeks.

METHODS

This study was a retrospective analysis of premature neonates born at a tertiary care center between 2011 and 2015 who received either furosemide or chlorothiazide. The primary outcome was incidence of MBD. Secondary outcomes included growth, electrolyte disturbances, oxygen requirement, and length of stay.

RESULTS

A total of 147 patients were included. Early initiation (n = 90) and late initiation (n = 57) arms were balanced with respect to birth weight and gestational age. There was no difference in incidence of MBD in the early group (76%) versus the late group (65%; p = 0.164). Stratification by cumulative dose showed incidence of 85% in patients receiving ≥8 mg/kg of furosemide, compared with 68% and 64% of those in the <4 mg/kg and 4 to 7.9 mg/kg strata, respectively (p = 0.06). The early group experienced greater reductions in length-for-age growth during diuretic therapy (-70% versus -40%; p = 0.009). Electrolyte abnormalities were more prevalent in the early group. Although there was no difference in duration of mechanical ventilation, duration of supplemental oxygen requirement was reduced in the late group (75 versus 89 days; p = 0.003).

CONCLUSIONS

Timing of diuretic initiation did not affect incidence of MBD. Increased cumulative furosemide exposure may be associated with higher incidence. Patients first exposed to diuretics within 2 weeks of life are at higher risk for electrolyte abnormalities and reduced growth velocity.

Development and Evaluation of a Family of Human Face and Upper Airway Models for the Laboratory Testing of Orally Inhaled Products

Many orally inhaled products are supplied with a facemask instead of a mouthpiece, enabling aerosolized medication to be transferred from the inhaler to the lungs when the user lacks the capability to use a mouthpiece. Until recently, laboratory evaluation of an orally inhaled product-facemask was frequently undertaken by removing the facemask, treating the facemask adapter as being equivalent to a mouthpiece. Measurements of delivered drug mass were therefore subject to bias arising from the absence of dead volume, had the facemask been present. We have described the development of the Aerosol Delivery to an Anatomic Model (ADAM) infant, small child, and adult faces and upper airways, and their subsequent evaluation. Each model possesses physical features of appropriate size, and the soft tissues are also simulated. Rudimentary underlying bony structure is also present, because its purpose is only to provide support, enabling the mechanical response of the facial soft tissues when a facemask is applied to be realized. A realistic upper airway (nasopharynx for the infant model, naso- and oropharynx for the child and oropharynx for the adult models) is also incorporated, so that each model can be used to determine the mass of inhaled medication likely to penetrate as far as the lungs where therapy is intended to be applied. Measurements of the mass of pressurized metered-dose inhaler-delivered salbutamol at a filter distal to the upper airway of each model, simulating age-appropriate tidal breathing, were remarkably consistent, almost all being in the range 0.3 to 1.0 μg/kg across the model age ranges, when expressed as a fraction of body weight.

Clinical-laboratory findings of bone metabolism in healthy premature and full-term neonates: preliminary results

Premature infants are a major risk group for bone metabolic disorders. The purpose of this study is to clarify certain aspects of bone metabolism in healthy preterm and full-term neonates. Forty neonates (20 preterm and 20 full-term) were the material of the study. For each neonate demographic data (gender, gestational week) and anthropometric data (body weight) were recorded. Blood samples were collected and biochemical markers of bone metabolism (serum ALP, Ca, P, Mg) were immediately estimated. According to the results there is a statistically significant difference in average ALP of preterm neonates compared to full term neonates. Slightly higher values of Ca, P, Mg occurred in premature neonates while there was a statistically significant difference in the weeks of gestation and body weights between the two groups. It is typical in premature neonates the decrease in levels of ALP by the weeks of gestation and the stable levels of Ca. Gestational week seems to positively affect P and Mg levels in preterm neonates. Conclusively from our study's results arises that the week of gestation and not so much the body weight influence the alterations of bone biochemical biomarkers in healthy premature newborns. It seems that very premature neonates have high levels of serum ALP in decompensation of lower levels of Mg and P from all the newborns in this study. Therefore in very premature neonates, it is recommended to estimate serum ALP, Mg and P for assessment of bone turnover.

Calcium and phosphorus supplementation of human milk for preterm infants

BACKGROUND

Preterm infants are born with low skeletal stores of calcium and phosphorus. Preterm human milk provides insufficient calcium and phosphorus to meet the estimated needs of preterm infants for adequate growth. Supplementation of human milk with calcium and phosphorus may improve growth and development of preterm infants.

OBJECTIVES

To determine whether addition of calcium and phosphorus supplements to human milk leads to improved growth and bone metabolism of preterm infants without significant adverse effects.

SEARCH METHODS

We used the standard search strategy of the Cochrane Neonatal Review Group to search the Cochrane Central Register of Controlled Trials (CENTRAL; 2016, Issue 3), MEDLINE via PubMed (1966 to 14 April 2016), Embase (1980 to 14 April 2016) and the Cumulative Index to Nursing and Allied Health Literature (CINAHL; 1982 to 14 April 2016). We also searched clinical trials databases (11 May 2016) and the reference lists of retrieved articles for randomised controlled trials and quasi-randomised trials.

SELECTION CRITERIA

Randomised and quasi-randomised trials comparing supplementation of human milk with calcium and/or phosphorus versus no supplementation in hospitalised preterm infants were eligible for inclusion in this review.

DATA COLLECTION AND ANALYSIS

Two review authors (JB, JW) independently extracted data and assessed trial quality using standard methods of the Cochrane Neonatal Review Group. We reported dichotomous data as risk ratios (RRs) and continuous data as mean differences (MDs) with 95% confidence intervals (CIs). We used the Grading of Recommendations Assessment, Development and Evaluation (GRADE) approach to assess the quality of evidence.

MAIN RESULTS

This is an update of a 2001 review that identified no eligible trials. One trial including 40 infants met the inclusion criteria for this review. Using GRADE criteria, we judged the quality of the evidence as low owing to risk of bias (inadequate reporting of methods of randomisation, allocation concealment and/or blinding) and imprecision (wide confidence intervals and data from a single small trial). We found no evidence of a difference between calcium and phosphorus supplementation versus no supplementation for neonatal growth outcomes (weight, length, head circumference) at any time point reported (two, four or six weeks postnatal age). At six weeks postnatal age, supplementation with calcium/phosphorus was associated with a decrease in serum alkaline phosphatase concentration (MD -56.85 IU/L, 95% CI -101.27 to -12.43; one randomised controlled trial (RCT); n = 40 infants). Investigators provided no data on growth at 12 to 18 months, neonatal fractures, feed intolerance, breastfeeding or any of the prespecified childhood outcomes for this review (fractures, growth, neurodevelopmental outcomes).

AUTHORS' CONCLUSIONS

We identified one small trial including only 40 infants that compared supplementation of human milk with calcium and phosphorus versus no supplementation in hospitalised preterm infants. We judged the evidence to be of low quality and found no evidence of differences between groups for clinically important outcomes including growth and fractures. Although serum alkaline phosphatase concentration was reduced in the group receiving supplementation at six weeks postnatal age, this difference is unlikely to be of clinical significance. We conclude that evidence is insufficient to determine whether benefit or harm ensues when human milk is supplemented with calcium and/or phosphorus for the hospitalised preterm infant. We see no advantage of conducting further trials of this intervention because with the advent of multi-component human milk fortifier, supplementation of human milk with calcium and/or phosphorus alone is no longer common practice. Future trials should consider assessing effects of multi-component fortifiers with different mineral compositions on clinically important outcomes during the neonatal period and in later childhood.

Correlation between plasma levels of arginine and citrulline in preterm and full-term neonates: Therapeutical implications

BACKGROUND

Preterm neonates exhibit several deficiencies that endanger their lives. Understanding those disturbances will provide tools for the management of preterm neonates. The present work focuses on arginine and citrulline which has been flagged among the biochemical landmarks of prematurity.

METHODS

We examined blood samples of preterm newborns as compared with mature neonates to determine the levels of arginine and citrulline by capillary zone electrophoresis with laser induced fluorescence detection (CZE-LIFD).

RESULTS

Significantly lower levels of arginine and citrulline were found in preterm neonates than in mature neonates (P<.01). Interestingly there was a highly significant correlation between the two amino acids in mature neonates (P<.0001). Such correlation was present in preterm neonates too (P<.01). Pearson coefficient showed that 60% of the citrulline concentration depends on arginine concentration in mature neonates. Only 20% of the citrulline concentration depends on arginine concentration in preterm neonates. Although the ratio arginine/citrulline was lower in preterm neonates than in mature neonates the difference was not statistically significant.

CONCLUSIONS

These results suggest that less arginine is converted to citrulline to form nitric oxide in preterm than in full-term neonates. The result is discussed in terms of the immature enzymatic systems in the preterm neonate.

Calcium to phosphorus ratio, essential elements and vitamin D content of infant foods in the UK: Possible implications for bone health

Adequate intake of calcium and phosphorus in the appropriate ratio of 1-2:1 (Ca:P), in addition to magnesium and vitamin D, is vital for bone health and development of infants. In this feasibility study, the ratio of Ca:P in conjunction with vitamin D and other essential elements (Cu, Fe, K, Mg, Na, and Zn) in a range of commercial infant food products in the UK was investigated. The elemental analysis was carried out using inductively coupled plasma optical emission spectrometry, and vitamin D levels were determined using an enzyme-linked immunosorbent assay. The quantitative data were further evaluated, based on a standardised menu, to measure the total daily intake of an infant aged 7-12 months against the Reference Nutrient Intake. The results from the study show that the Ca:P ratio of the infant's total dietary intake was within the recommended range at 1.49:1. However, the level of intake for each of the nutrients analyzed, with the exception of sodium, was found to be above the Reference Nutrient Intake, which warrants further investigation in relation to both micronutrient interactions and in situations where the intake of fortified infant formula milk is compromised. Finally, as the study is the first to include consumption of infant snack products, the level of total calorie intake was also calculated in order to assess the total daily estimated energy intake; the results indicate that energy intakes exceed recommendations by 42%, which may have implications for obesity.

Serial serum alkaline phosphatase as an early biomarker for osteopenia of prematurity

Metabolic bone disease of prematurity is a condition characterized by reduction in bone mineral content (osteopenia). It is a problem faced by very low birth weight (VLBW) infants because of lack of fetal mineralization during the last trimester. Our aim was to assess serum alkaline phosphatase (ALP) level as an early biomarker for osteopenia in premature infants and to estimate an optimal cutoff value of serum ALP at which osteopenia is detected radiologically in premature newborns.This prospective study was conducted on a cohort of 120 newborn infants of both sex of ≤34 weeks' gestational age and <1500 g birth weight. Two blood samples, from each infant on at least 2 consecutive weeks, were reported for calcium, phosphorus, and ALP. Evidence of osteopenia was evaluated radiologically by performing wrist/knee x-ray.Sixteen infants (13.3%) had evidence of osteopenia in x-ray, whereas 104 infants (86.7%) were nonosteopenic and all the osteopenic infants were <1000-g birth weight. Birth weight and gestational age were significantly inversely related to serum ALP levels. Both samples showed statistically significantly higher mean ALP level in osteopenic than nonosteopenics (P < 0.001, and P < 0.001 respectively). There was no constant value of serum ALP related to radiologic evidence of osteopenia. However, the optimal cutoff value of serum ALP at which osteopenia is detected is 500 IU/L with 100% sensitivity and 80.77% specificity.High levels of ALP can be considered a reliable biomarker to predict the status of bone mineralization and the need for radiological evaluation in premature infants particularly those <1000-g birth weight and <32 weeks' gestation.

Effects of parenteral phosphorus dose restriction in preterm infants

BACKGROUND

In response to a national shortage of parenteral phosphorus solutions (2013), a hospital-wide phosphorus dose restriction strategies was implemented which included judicious use of phosphorus in preterm infants <1250 g birth weight and no parenteral phosphorus in preterm infants >1250 g birth weight unless they have a critically low phosphorus level.

OBJECTIVE

To study the effect of parenteral phosphorus dose restriction in preterm infants admitted to the neonatal intensive care unit.

METHODS

Preterm infants (≤35 weeks birth gestation and ≤2500 g birth weight) who received parenteral nutrition, survived >1 week and had no major congenital anomalies were studied. Clinical and laboratory data in the first 4 weeks of life of infants admitted during the parenteral phosphorus shortage (cases) were compared to infants who were admitted 6 months prior to the shortage (controls).

RESULTS

Twenty consecutive cases were compared to 40 consecutive controls. Cases had lower serum phosphorus levels, higher serum alkaline phosphatase levels, and need for greater inotropic support compared to controls. These differences were significant only in preterm infants with birth weight >1250 g, the group who received more parenteral phosphorus dose restriction while they were similar in preterm infants with birth weight <1250 g.

CONCLUSION

The modest effects of phosphorus dose restriction may become more clinically important if shortage is prolonged or severe or if it involves extreme preterm infants.

Bone status in preterm infant: influences of different nutritional regimens and possible markers of bone disease

OBJECTIVE

The objective of this study was to evaluate possible influences of parenteral nutrition on growth and bone development in preterms and to search for markers of bone status.

STUDY DESIGN

Metacarpus bone transmission time (mc-BTT) was performed at birth, 21 days and 36 weeks of gestational age (GA) in preterms, receiving two different nutritional regimens, together with biochemical analysis.

RESULT

A total of 234 patients were studied. Newborns with aggressive nutrition had significantly better growth rate and higher values of mc-BTT until discharge. Mc-BTT at day 21 correlates positively with nutritional intakes and phosphatemia; lower limb length positively correlated with mc-BTT (P<0.01). Newborns with low energy intake in the first week of life (<70 kcal kg(-1) per day) and low serum phosphate level (<1.4 mmol l(-1)) at 21 days had lower mc-BTT at 36 weeks of GA (P<0.01).

CONCLUSION

Aggressive parenteral intakes in preterms improve growth and bone status in the short-medium term, suggesting that early nutrition could influence bone development.

Cord Blood Ferritin and Fibroblast Growth Factor-23 Levels in Neonates

CONTEXT

Elevated levels of the phosphate-regulating hormone, fibroblast growth factor-23 (FGF-23) are associated with skeletal and cardiovascular disease. Levels of FGF-23 are elevated in neonates, but the mechanisms are poorly understood. Iron deficiency is a recently described stimulus for FGF-23 production.

OBJECTIVE

To test the hypothesis that lower fetal iron status, as measured by lower cord blood ferritin, is independently associated with elevated FGF-23 levels in neonates.

DESIGN AND PARTICIPANTS

This is a cross-sectional study of 64 full-term, healthy neonates.

SETTING

This study took place in a university-based, tertiary care center.

MAIN OUTCOME MEASURES

Plasma levels of second generation C-terminal FGF-23 (cFGF-23) and intact FGF-23 (iFGF-23).

RESULTS

Levels of cFGF-23 ranged from 108 to 7508 reference units (RU)/ml (median, 824 RU/ml), and iFGF-23 from undetectable (<8.5) to 135.4 pg/ml (median, <8.5 pg/mL). Ferritin ranged from 58 to 719 ng/ml (mean, 203 ng/ml). Lower cord blood ferritin levels were associated with higher cFGF-23 (r = −0.320; P = .014), but not iFGF-23 levels (r = −0.222; P = .082). In multivariate analyses adjusted for glycemic indices, maternal race, and parity, lower ferritin levels remained independently associated with higher cFGF-23 levels (B = −0.261, P = .01). In the full models, higher cord blood glucose and C-peptide levels were also independently associated with higher cFGF-23 levels.

CONCLUSIONS

cFGF-23, but not iFGF-23 levels, are elevated in cord blood of healthy term neonates and independently associated with lower serum ferritin and higher glycemic indices.

Metabolic bone disease in the preterm infant: Current state and future directions

Neonatal osteopenia is an important area of interest for neonatologists due to continuing increased survival of preterm infants. It can occur in high-risk infants such as preterm infants, infants on long-term diuretics or corticosteroids, and those with neuromuscular disorders. Complications such as rickets, pathological fractures, impaired respiratory function and poor growth in childhood can develop and may be the first clinical evidence of the condition. It is important for neonatologists managing such high-risk patients to regularly monitor biochemical markers for evidence of abnormal bone turnover and inadequate mineral intake in order to detect the early phases of impaired bone mineralization. Dual-energy X-ray absorptiometry has become an increasingly used research tool for assessing bone mineral density in children and neonates, but more studies are still needed before it can be used as a useful clinical tool. Prevention and early detection of osteopenia are key to the successful management of this condition and oral phosphate supplements should be started as soon as is feasible.

Daily physical activity in low-risk extremely low birth weight preterm infants: positive impact on bone mineral density and anthropometric measurements

The aim of this study was to evaluate the changes in bone mineral density and anthropometric indices of extremely low birth weight (ELBW) preterm infants undergoing daily physical activity. Twenty-eight low-risk ELBW preterm infants (intervention group = 14, control group = 14) with a birth weight of under 1000 g and gestational age of 26-32 weeks were recruited. Preterm 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. In this study, the tibial SOS values were found to be increased in the intervention group (+111.14 m/s) (p = 0.001) and decreased in the control group (-58.21 m/s) (p = 0.030). The increase in percentage of body weight, height, and tibial length of infants in the intervention group was significantly higher than in the control group (respectively; p = 0.002, p = 0,015, p < 0.001). A daily physical activity programme increased body weight, height, tibial length, and SOS values of the tibia in ELBW preterm infants.

Evaluation of bone metabolism in newborn twins using quantitative ultrasound and biochemical parameters

Metabolic bone disease (MBD) is one of the important complications of prematurity. Early and adequate nutritional interventions may reduce the incidence and potential complications of MBD. The present study aimed to evaluate bone metabolism in twins via biochemical parameters and quantitative ultrasound (QUS) and to compare the results between twin pairs. Moreover, twin infants were evaluated in terms of potential risk factors likely to have impact on MBD. Forty-three pairs of twins were included in the study. Serum calcium, phosphorus, magnesium, and alkaline phosphatase concentrations were assessed and bone mineral density was measured using QUS (speed of sound, SOS) at postnatal 30 d. Co-twin with the higher birth weight was assigned to Group 1 (n = 36) and the other twin was assigned to Group 2 (n = 36). Birth weight and head circumference were significantly higher in the infants of Group 1 compared with Group 2. No significant difference was found among the groups in terms of gender, history of resuscitation, length of stay in intensive care unit (ICU) or in the incubator, duration of total parenteral nutrition (TPN), type of nutrition, vitamin D use, biochemical parameters, and the SOS value. The factors likely to affect SOS, including type of pregnancy, maternal drug use, gender of infant, birth weight, head circumference at birth, gestational week, length of stay at the ICU, duration of TPN, type of nutrition, resuscitation, vitamin D use, and levels of calcium, phosphorus, magnesium, and alkaline phosphatase were entered into the model. The phosphorus level and the maternal drug use were found to be the factors that significantly reduced SOS, whereas pregnancy after assisted reproductive techniques was found to be a significant enhancing factor.

Differential low uptake of free vitamin D supplements in preterm infants: the Quebec experience

Background

Vitamin D is essential for bone mineralization, particularly in premature infants. For nearly 20 years, Quebec has offered a program of free vitamin D supplements via its public medication insurance plan Régie de l’Assurance Maladie du Québec (RAMQ). The objective of this study is to evaluate the number of preterm infants that obtained at least one bottle (50 doses) of vitamin D supplement through this program and to determine if uptake varied by gestational age.

Methods

This was a retrospective cohort study of preterm infants covered by RAMQ and born from 1998 to 2008; all infants had 1 year of follow-up data regarding supplement use. Data were extracted from the Quebec Pregnancy Cohort, a linked administrative database and were stratified by early (<34 weeks) or late gestational age premature infants. The number of infants obtaining supplements was the primary outcome and their characteristics were compared across gestational age groups. Predictors for participation (obtaining at least 1 bottle) or adherence (2 or more bottles) were identified via logistic regression (GEE).

Results

10288 infants were eligible; the percentage exposed to vitamin D was 24.5% (37.4%- early; 20.7%-late preterm infants, p < 0.001). The median number of bottles obtained was 2 for early and 1 for late preterms. For all premature infants, there was an apparent geometric decline in the infants obtaining subsequent bottles of supplements over the 12 month period. Additionally, there was a significant decline in program participation over time (OR = 0.90/year, 95% CI: 0.89-0.90) regardless of gestational age. Older or more educated mothers were positive predictors for participation. A prescription from a pediatrician significantly increased the odds of obtaining the supplement.

Conclusion

Early preterm infants were more likely to obtain the supplement post-discharge; uptake was low and decreased with time for both age categories. Specifically, targeting late preterm infants and young mothers with less education could improve vitamin D uptake.

Metabolic bone disease screening practices among U.S. neonatologists

Preterm, low-birth-weight neonates are predisposed to metabolic bone disease (MBD). This survey aimed to assess screening, diagnostic, and treatment practices in U.S. level IIIB/IIIC neonatal intensive care units (NICUs). A 29-question anonymous online survey was e-mailed to American Academy of Pediatrics Perinatal Section members. 338 neonatologists, representing 246 IIIB/IIIC NICUs, responded. 86% reported MBD screening. Screening was primarily based on gestational age (71%), with thresholds <26 to <36 weeks. Other criteria included birth weight (64%), total parenteral nutrition duration (48%), X-ray findings (56%), diuretic use (41%), and exclusive breast-feeding (9.6%). Almost universally, diagnosis was based on elevated alkaline phosphatase, most commonly >500 U/L (58.6%). 52% used X-ray for diagnosis. Treatment included human milk fortification (83%), vitamin D (67%), calcium (65%), and phosphorus (65%) supplementation. Our survey confirms widespread awareness of MBD but highlights lack of consensus regarding definition, screening, and treatment. Further research is needed to develop and optimize strategies to prevent, recognize, and manage MBD.

Parathyroid hormone as a marker for metabolic bone disease of prematurity

OBJECTIVE

To compare parathyroid hormone to alkaline phosphatase as a serologic marker for metabolic bone disease (MBD) in preterm infants.

STUDY DESIGN

An 18-month prospective observational study in neonates with birth weight < 1250 g. Simultaneous serum parathyroid hormone (PTH), alkaline phosphatase (ALP), calcium (Ca) and phosphorus (P) were measured at scheduled intervals during hospitalization. At 6 weeks of age, MBD was evaluated using knee radiographs. Comparisons were analyzed using multivariate logistic regression, receiver operating characteristic (ROC) curves, χ² and Student t-test.

RESULT

Fourty-nine infants were included in the study: 7 with severe and 42 with mild MBD. Using ROC curves, at 660 U l⁻¹ ALP had a sensitivity of 29% and specificity of 93% for severe MBD, while a cutoff point of 180 pg ml⁻¹ gave PTH a sensitivity of 71% and specificity of 88%. Infants with severe bone disease had a lower birth weight, 21-day serum P, an increased use of glucocorticoids and caffeine, and more likely to have major neonatal morbidities.

CONCLUSION

PTH is an early marker with better sensitivity than ALP in screening for MBD. At 3 weeks chronologic age, a PTH level > 180 mg dl⁻¹ or a P level <4.6 pg ml⁻¹ yielded a sensitivity of 100% and specificity of 94% for severe MBD [corrected].

Metabolic bone disease and bone mineral density in very preterm infants

OBJECTIVES

To evaluate bone mineral density (BMD) in preterm neonates at discharge and identify the optimum cutoff values for serum alkaline phosphatase (ALP) and phosphorus (P) concentrations to diagnose the severity of metabolic bone disease of prematurity.

STUDY DESIGN

A total of 336 preterm neonates (≤ 31 weeks' gestation and birth weight ≤ 1500 g) were prospectively evaluated for BMD before discharge using dual-energy X-ray absorptiometry.

RESULTS

BMD reference values (at ALP ≤ 500 IU/L) were measured in 279 patients. BMD was classified as poor (<10th percentile) at <0.068 g/cm(2), fair (10th-25th percentile) at 0.068-0.081 g/cm(2), good (25th-75th percentile) at 0.081-0.112 g/cm(2), and very good (>75th percentile) at >0.112 g/cm(2). Increased BMD was associated with a higher birth weight, short duration of parenteral nutrition, and the absence of small for gestational age status, patent ductus arteriosus, intraventricular hemorrhage, and other clinical variables. Metabolic bone disease of prematurity was absent (ALP ≤ 500 IU/L) in 279 cases (83.0%), mild (ALP >500 IU/L and P ≥ 4.5 mg/dL) in 46 cases (13.7%), and severe (ALP >500 IU/L and P <4.5 mg/dL) in 11 cases (3.3%).

CONCLUSIONS

A BMD >0.068 g/cm(2) at discharge indicated a 90.3% probability of not developing metabolic bone disease of prematurity. The factors independently associated with increased BMD included higher birth weight, short duration of parenteral nutrition, absence of intraventricular hemorrhage, exclusive feeding of fortified breast milk, and older age at discharge.