Skeletal changes in preterm infants

Radiological insights into pediatric undernutrition: Early detection, complications, and a structured evaluation approach

Despite a decade of significant growth in economic conditions of South Asian countries, people continue to suffer from the pervading problem of malnutrition. High prevalence of child undernutrition despite unprecedented economic growth in these nations have a multifactorial etiology including fetal malnutrition and status of women, inadequate feeding practices in infant and young child, poor household sanitation and untargeted health schemes. The diagnosis and management of malnutrition and its various complications require a multidisciplinary approach and radiologists have a potentially important, albeit currently underutilized, role in early detection, identifying the other clinical mimics such as endocrinal and genetic disorders, and detection of key complications. In this review, we apprise the radiological aspects of PEM and micro-nutritional deficiency and their complications. We also provide a comprehensive structured evaluation scheme for evaluation of a suspected malnourished child.

Implementation of Parenteral Nutrition Formulations with Increased Calcium and Phosphate Concentrations and Its Impact on Metabolic Bone Disease in Preterm Infants: A Retrospective Single-Centre Study

Background: Metabolic Bone Disease of Prematurity (MBDP) is common in extremely preterm infants (≤28 weeks gestation). Parenteral nutrition (PN) with higher calcium (Ca) and phosphorus (P) concentration started soon after birth may improve bone health in preterm infants. We compared the effect of two standard PN formulations on the incidence of MBDP and explored the predictive ability of biochemical markers for diagnosing MBDP. Methods: This retrospective study included eligible preterm infants ≤ 28 weeks gestation. Infants in group 1 (January 2016-December 2017) received PN 1 formulation with lower Ca (1.6 mmol/kg/day) and P concentration (1.4 mmol/kg/day). Infants in group 2 (June 2018-May 2020) received PN 2 formulation with higher Ca (2.3 mmol/kg/day) and P concentration (1.8 mmol/kg/day). We reviewed the biochemical and radiological investigations performed for diagnosing MBDP. Results: The incidence of MBDP reduced from 82.8% (77/93) in group 1 to 47.3% (27/57) in group 2. Grade 2-3 MBDP reduced significantly from 14% in group 1 to none in group 2 (p < 0.01). Serum phosphate < 1.5 mmol/L had a sensitivity of 79% and specificity of 77%, and alkaline phosphatase > 500 U/L showed a sensitivity of 72% and specificity of 71% for diagnosing radiological MBDP. There was no increase in hypercalcemia, hypophosphatemia or nephrocalcinosis from PN 2 formulation. Conclusions: A higher Ca and P concentration in PN reduced MBDP and eliminated grade 2-3 MBDP in our cohort without an increase in adverse events. Low serum phosphate and high serum alkaline phosphatase were the best predictors for diagnosing MBDP.

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.

A Multidisciplinary and a Comprehensive Approach to Reducing Fragility Fractures in Preterm Infants

With advances in neonatal care, bone fractures prior to discharge from the hospital in preterm infants receiving contemporary neonatal care, are rare. Nevertheless, such fractures do occur in very low birth weight and extremely low birth weight infants who go on to develop metabolic bone disease of prematurity (MBDP), with or without secondary hyperparathyroidism. MBDP is a multifactorial disorder arising from the disruption of bone mass accrual due to premature birth, postnatal immobilisation, and loss of placental oestrogen resulting in bone loss, inadequate provision of bone minerals from enteral and parenteral nutrition, and medications that leach out bone minerals from the skeleton. All of these factors lead to skeletal demineralisation and a decrease in bone strength and an increased risk of fractures of the long bones and ribs. Secondary hyperparathyroidism resulting from phosphate supplements, or enteral/parenteral feeds with a calcium-tophosphate ratio of < 1.3:1.0 leads to subperiosteal bone resorption, cortical thinning, and further skeletal weakening. Such fractures may occur from routine handling and procedures such as cannulation. Most fractures are asymptomatic and often come to light incidentally on radiographs performed for other indications. In 2015, we instituted a comprehensive and multidisciplinary Neonatal Bone Health Programme (NBHP), the purpose of which was to reduce fragility fractures in highrisk neonates, by optimising enteral and parenteral nutrition, including maintaining calcium-tophosphate ratio ≥1.3:1, milligram to milligram, biochemical monitoring of MBDP, safe-handling of at-risk neonates, without compromising passive physiotherapy and skin-to-skin contact with parents. The at-risk infants in the programme had radiographs of the torso and limbs at 4 weeks and after 8 weeks from enrolment into the program or before discharge. Following the introduction of the NBHP, the bone fracture incidence reduced from 12.5% to zero over an 18-month period.

Prenatal and Neonatal Bone Health: Updated Review on Early Identification of Newborns at High Risk for Osteopenia

Bone health starts with maternal health and nutrition, which influences bone mass and density already in utero. The mechanisms underlying the effect of the intrauterine environment on bone health are partly unknown but certainly include the 'foetal programming' of oxidative stress and endocrine systems, which influence later skeletal growth and development. With this narrative review, we describe the current evidence for identifying patients with risk factors for developing osteopenia, today's management of these populations, and screening and prevention programs based on gestational age, weight, and morbidity. Challenges for bone health prevention include the need for new technologies that are specific and applicable to pregnant women, the foetus, and, later, the newborn. Radiofrequency ultrasound spectrometry (REMS) has proven to be a useful tool in the assessment of bone mineral density (BMD) in pregnant women. Few studies have reported that transmission ultrasound can also be used to assess BMD in newborns. The advantages of this technology in the foetus and newborn are the absence of ionising radiation, ease of use, and, above all, the possibility of performing longitudinal studies from intrauterine to extrauterine life. The use of these technologies already in the intrauterine period could help prevent associated diseases, such as osteoporosis and osteopenia, which are characterised by a reduction in bone mass and degeneration of bone structure and lead to an increased risk of fractures in adulthood with considerable social repercussions for the related direct and indirect costs.

Diagnostic markers of metabolic bone disease of prematurity in preterm infants

Due to the higher birth rate of preterm infants and improvements in their management, metabolic bone disease of prematurity (MBDP) has a high incidence and is attracting attention. However, clear indicators for the early diagnosis of MBDP are lacking. We aimed to explore simple and feasible early warning indicators for diagnosing MBDP. Our study collected case data of premature infants from two medical centers in Chongqing from January 2020 to February 2022. According to the inclusion and exclusion criteria, data from 136 cases were collected. The correlation between 14 variables in each case and the occurrence of MBDP was analyzed. According to area under the receiver operating characteristic curve (AUROC) analysis, the best cutoff value for each variable was determined. Potential predictors were selected, and Least Absolute Shrinkage and Selection Operator (LASSO) regression analysis was used to establish the association of two models with MBDP, whose results were used to develop a diagnostic nomogram. Furthermore, a model decision curve was analyzed. Four predictors were selected from 14 clinical variables by LASSO regression, and Model I was established, including the following characteristics: height (>36 cm), head circumference (≤29.49 cm), total serum calcium (Ca) (>2.13 mmol/L), and alkaline phosphatase (ALP) (>344 U/L) levels. A single predictor, the ALP level (>344 U/L), was used to establish Model II. The AUROC values of the two models were 0.959 for Model I and 0.929 for Model II. In conclusion, in this study, two diagnostic models of MBDP were developed using four combinations of predictors and ALP as a single predictor. Both models showed good sensitivity and specificity for the early diagnosis of metabolic bone disease (MBD), and an ALP level of 344 U/L was defined as a simple and effective diagnostic threshold. In future studies, using larger samples, diagnostic threshold values of ALP for premature infants of different ages should be established, and internal and external validations are needed to improve the adaptability of the current model.

Sodium Glycerophosphate Use in Parenteral Nutrition Improves Mineral Metabolism in Extremely Low Birth Weight Infants

OBJECTIVE

To evaluate the clinical effect of sodium glycerophosphate (NaGP) in parenteral nutrition solutions on mineral metabolism in extremely low birth weight (ELBW) infants.

STUDY DESIGN

NaGP was introduced for use in place of potassium phosphate (K₃PO₄) in January 2018; this retrospective cohort study included 95 ELBW infants treated with K₃PO₄ between January 2015 and December 2017 and 77 infants treated with NaGP between August 2018 and January 2021. Mineral intake over the first 14 days; changes in serum calcium, phosphorus, sodium, and alkaline phosphatase (ALP) levels over the first 1-3 months; and the rates of electrolyte imbalance and clinical morbidity were compared. High-risk infants who had nil per os (NPO) status for >14 days and prolonged parenteral nutrition exposure were further analyzed as a subgroup.

RESULTS

The use of NaGP instead of K₃PO₄ significantly increased Ca and P intake, but intakes remained below the recommended range (Ca, 64-140 mg/kg/day; P, 50-108 mg/kg/day). Compared with levels in the K₃PO₄ group, the NaGP group had significantly higher serum Ca and P levels after day 14 and lower ALP levels after day 56. In the subgroup analysis, the NaGP group had significantly lower incidences of hypophosphatemia, hyponatremia, bronchopulmonary dysplasia, and ALP >500 IU/L.

CONCLUSIONS

Although the administration of NaGP instead of K₃PO₄ in parenteral nutrition regimens still did not provide adequate Ca and P intake for ELBW infants, higher intake significantly improved serum Ca and P levels, especially in ELBW infants with prolonged parenteral nutrition exposure.

Don't Forget the Bones: Incidence and Risk Factors of Metabolic Bone Disease in a Cohort of Preterm Infants

Metabolic bone disease of prematurity (MBD) is a condition of reduced bone mineral content (BMC) compared to that expected for gestational age (GA). Preterm birth interrupts the physiological process of calcium (Ca) and phosphorus (P) deposition that occurs mostly in the third trimester of pregnancy, leading to an inadequate bone mineralization during intrauterine life (IUL). After birth, an insufficient intake of Ca and P carries on this alteration, resulting in overt disease. If MBD is often a self-limited condition, in some cases it could hesitate the permanent alteration of bone structures with growth faltering and failure to wean off mechanical ventilation due to excessive chest wall compliance. Despite advances in neonatal intensive care, MBD is still frequent in preterm infants, with an incidence of 16−23% in very-low-birth-weight (VLBW, birth weight <1500 g) and 40−60% in extremely low-birth-weight (ELBW, birth weight <1000 g) infants. Several risk factors are associated with MBD (e.g., malabsorption syndrome, parenteral nutrition (PN), pulmonary bronchodysplasia (BPD), necrotizing enterocolitis (NEC), and some chronic medications). The aim of this study was to evaluate the rate of MBD in a cohort of VLBWI and the role of some risk factors. We enrolled 238 VLBWIs (107 male). 52 subjects were classified as increased risk (G1) and 186 as standard risk (G2) according to serum alkaline phosphatase (ALP) and phosphorus (P) levels. G1 subjects have lower GA (p < 0.01) and BW (p < 0.001). Moreover, they need longer PN support (p < 0.05) and invasive ventilation (p < 0.01). G1 presented a higher rate of BPD (p = 0.026). At linear regression analysis, BW and PN resulted as independent predictor of increased risk (p = 0.001, p = 0.040, respectively). Preventive strategies are fundamental to prevent chronic alteration in bone structures and to reduce the risk of short stature. Screening for MBD based on serum ALP could be helpful in clinical practice to identify subjects at increased risk.

The incidence of osteopenia of prematurity in preterm infants without phosphate supplementation: A prospective, observational study

To meet their requirements for bone mineralization, it is recommended that preterm infants receive nutritional support containing calcium and phosphate. There are no clear data on the incidence of osteopenia of prematurity (OFP) in preterm infants without phosphate supplementation.This study aimed to investigate the incidence of OFP in preterm infants without phosphate supplementation and its relationship with the duration of parenteral nutrition (PN).This was a prospective and observational study.This study included 30 infants aged <32 gestational weeks and weighed <1500 g at birth. All infants received PN according to a standard protocol, beginning on day 1 with calcium, without phosphate. Starting from the first day of life, all infants received human milk without fortifiers. Oral vitamin D (400 IU/d) was administered when enteral nutrition reached 100 mL/kg/d.The diagnosis of OFP was based on radiographs that were taken of both wrists. Serum alkaline phosphatase (ALP) was measured 3 times: at the start of PN (ALP 1), at the end of PN (ALP 2), and at discharge or the expected due date (ALP 3). Radiographs were obtained on the same day as ALP 3. The duration of PN was analyzed in the presence of OFP using receiver operating characteristic curve analysis.Among the 30 infants, 13 (43%) were diagnosed with OFP. The duration of PN was significantly longer in the OFP group than in the group without OFP (16 vs 12 days; P < .05). The provision of PN for >15 days significantly increased the risk of OFP (odds ratio, 5.40; 95% confidence interval, 1.12-26.04; P = .035).We found a high incidence of OFP in preterm infants without phosphate supplementation. An association was found between the duration of PN and the incidence of OFP. Further research is needed to prevent the development of osteopenia in preterm infants.

Associated neonatal and maternal factors of osteopenia of prematurity in low resource setting: A cross-sectional study

Objective

Determining neonatal and maternal factors that are associated with the incidence of OFP.

Methods

This study employed a cross-sectional design, in which the participants were identified for clinical variables (sex, gestational age, birth weight, etc.), neonatal morbidity (sepsis, necrotizing enterocolitis (NEC), etc.), and maternal risk factors (premature rupture of membranes, preeclampsia, etc.). The data were analyzed using Chi-square test, independent t-test, and logistic regression test with p < 0.05.

Results

The birth weight ranged from 800 to 1495 g (1219 ± 225 g), of which 5 newborns (17%) were <1000 g. The gestational age ranged from 27 to 32 weeks, with a mean of 29 ± 1.5 weeks. The signs of OFP were observed in 13 (43%) infants, of which 2 (15%) OFP infants had a birth weight <1000 g. There was significant difference in parenteral nutrition duration (p = 0.018), onset of vitamin D supplementation (p = 0.019), and ALP level (p = 0.012) of infants between the OFP group and the non-OFP group. The variables associated with the incidence of OFP were parenteral nutrition duration >15 days (OR = 5.4; 95% CI 1.120-26.044; p = 0.036), ALP level >500 U/L (OR = 2.889; 95% CI 1.703-4.900; p = 0.014), and PROM (OR = 5.4; 95% CI 1.039-28.533; p = 0.045).

Conclusion

The lack of phosphate intake, prolonged parenteral nutrition, ALP level >500 U/L, onset of vitamin D supplementation, and premature rupture of membranes are associated with the incidence of OFP.

Evaluation of radiologic evidence of metabolic bone disease in very low birth weight infants at fourth week of life

AIM

The aim of this study is to determine the incidence of metabolic bone disease (MBD) and assess the risk factors for development radiologic evidence of MBD.

METHODS

Preterm infants with gestational age ≤32 weeks and birth weight ≤1500 g were included in this prospective study. Metabolic bone disease was defined as hypophosphatemia (phosphorus levels <4 mg/dl), ALP levels >450 U/L, or radiologic findings of MBD at four weeks of age.

RESULTS

The study included 254 infants (gestational age: 29 (27-30) weeks, birth weight: 1130 g (960-1300)). Metabolic bone disease was diagnosed in 96 patients (37%); 48 infants had only radiologic evidence of MBD, 24 infants had only biochemical diagnosis of MBD, and 24 infants had both radiologic evidence of MBD and biochemical diagnosis of MBD.

CONCLUSIONS

Our results showed that radiologic evidence of MBD existed in some infants with normal biochemical results. That finding may guide further development of screening programs for MBD.

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.

Appropriate Phosphorus Intake by Parenteral Nutrition Prevents Metabolic Bone Disease of Prematurity in Extremely Low-Birth-Weight Infants

BACKGROUND

Metabolic bone disease (MBD) is a common disorder in extremely low-birth-weight (ELBW) infants. However, no studies have investigated whether high-dose calcium (Ca) and phosphorus (P) supplementation by parenteral nutrition (PN) prevents MBD in ELBW infants. This study aimed to identify the effect of PN on MBD in ELBW infants.

METHODS

We retrospectively analyzed ELBW infants who were admitted between April 2011 and March 2017. ELBW infants were divided into the low-P group (n = 22) and the high-P group (n = 26) according to the dose of parenteral P supply. Biochemical and radiological markers of MBD and treatments were analyzed.

RESULTS

Mean daily parenteral intake of Ca and P in the first week was significantly higher in the high-P group than in the low-P group (both P ≤ .001). Serum alkaline phosphatase (ALP) levels were significantly higher in the low-P group than in the high-P group in the first month. ELBW infants in the low-P group received alfacalcidol much more frequently than those in the high-P group. There was a trend of a higher rate of x-ray changes in the low-P group than in the high-P group. No infants developed bone fractures.

CONCLUSION

Appropriate P intake by PN is required to ensure high Ca intake, reduce ALP levels in the first month, and prevent MBD from hyperparathyroidism and does not worsen x-ray findings in ELBW infants.

Screening for Metabolic Bone Disease of prematurity

Metabolic bone disease (MBD) of prematurity remains a significant comorbid condition in preterm, low birth weight infants. As the majority of in utero calcium (Ca) and phosphorus (Phos) accretion occurs during the third trimester, many of these children have inadequate mineral stores and are at risk for deficiencies of Ca and Phos. While fortification of formula has allowed for increased mineral delivery to premature infants, intestinal immaturity prevents optimal absorption. This is compounded by immobilization, delayed establishment of enteral feeds, long term parenteral nutrition and medications that may alter mineral levels. Over time, biochemical changes occur and accompany MBD, with poor bone mineralization during this period increasing the risk for complications such as osteopenia, rickets and fractures. Screening is largely based on risk factors, but despite the 2013 AAP Consensus Statement, there remains significant variation in screening practices across institutions. A combination of laboratory and radiologic testing is often used to diagnose and manage MBD of prematurity, but there exists a lack of consensus on which screening tests and thresholds to use. This is in part related to a lack of normative data and clinical trials for preterm infants, and a result, a lack of evidence-based guidelines on the diagnosis and timing of potential treatment. Biochemical markers, such as serum Phos, alkaline phosphatase (ALP) and parathyroid hormone (PTH), have shown some benefit in the diagnosis of MBD in some studies, but have not always been reproducible. Radiographs may identify different degrees of skeletal changes, but these changes may not be detected until later in MBD development. Other modalities, such as DXA and ultrasound, have also been used, but these may be limited by lack of standards in preterm infants or lack of availability in some centers. Further research, more specifically clinical trials, are needed to determine which combination of tests can detect MBD at its earliest, in order to promote early treatment and prevent short- and long-term complications of MBD.

History, epidemiology and prevalence of neonatal bone mineral metabolic disorders

The evolutionary patterns of human migration and historical pre/post-industrial revolution have changed the face of bone metabolic disease through past centuries. Cultural, religious, and lifestyle practices continue to alter nutritional recommendations for this expanding diagnosis. Likewise, modern advancements in the field of neonatology and, more specifically, aggressive nutritional management of premature infants have shaped the epidemiology of neonatal bone metabolism over the past two decades. Decreased use of long-term parenteral nutrition, early fortification of enteral nutrition, and stringent American Academy of Pediatrics (AAP) practice guidelines instituting early supplementation of vitamin D have attributed to improved bone mineralization outcomes in both term and preterm infants. Nevertheless, neonatal bone mineral metabolic disorders remain prevalent. In this review, we provide an in-depth look at the diagnoses, therapeutics, and subset populations-both genetic and non-genetic-affected by neonatal bone mineral metabolic disorders.

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.

Caffeine is a risk factor for osteopenia of prematurity in preterm infants: a cohort study

Background

Caffeine, the most commonly used medication in Neonatal Intensive Care Units, has calciuric and osteoclastogenic effects.

Methods

To examine the association between the cumulative dose and duration of therapy of caffeine and osteopenia of prematurity, a retrospective cohort study was conducted including premature infants less than 31 weeks and birth weight less than 1500 g. Osteopenia of prematurity was evaluated using chest X-rays on a biweekly basis over 12 weeks of hospitalization.

Results

The cohort included 109 infants. 51% had osteopenia of prematurity and 8% had spontaneous rib fractures. Using the generalized linear mixed model, caffeine dose and duration of caffeine therapy showed a strong association with osteopenia of prematurity. Steroids and vitamin D were also significantly correlated with osteopenia of prematurity while diuretic use did not show a statistically significant effect.

Conclusion

The cumulative dose and duration of therapy of caffeine, as well as steroid are associated with osteopenia of prematurity in this cohort. Future studies are needed to confirm these findings and determine the lowest dose of caffeine needed to treat effectively apnea of prematurity.

Feasibility of quantitative ultrasonography for the detection of metabolic bone disease in preterm infants - systematic review

Metabolic bone disease of prematurity is characterised by disordered bone mineralisation and is therefore an increased fracture risk. Preterm infants are especially at risk due to incomplete in utero bone accretion during the last trimester. Currently, diagnosing metabolic bone disease mainly relies on biochemistry and radiographs. Dual-energy x-ray absorptiometry and quantitative ultrasound (US) are used less frequently. However, biochemical measurements correlate poorly with bone mineralisation and although scoring systems exist for metabolic bone disease, radiographs are subjective and do not detect early features of osteopenia. Dual energy x-ray absorptiometry is the reference standard for determining bone density in older children and adults. However, challenges with this method include movement artefact, difficulty scanning small and sick infants and a lack of normative data for young children. Quantitative US has a relatively low cost, is radiation-free and portable, and may hence be suitable for assessing bone status in preterm infants. This review aims to provide an overview of the use of quantitative US in detecting metabolic bone disease in preterm infants.

Growth and Bone Mineralization of Very Preterm Infants at Term Corrected Age in Relation to Different Nutritional Intakes in the Early Postnatal Period

Preterm infants often have a reduced bone mineral content (BMC) with increased risk of metabolic bone disease. After birth it is difficult to supply calcium (Ca) and phosphorus (P) comparable to the high fetal accretion rate. It is not known whether high supplementation of minerals in the early postnatal period improves growth and bone mineralization. The aim of this study was to evaluate growth and bone mineralization at term corrected age (TCA) in very and extremely preterm infants who received different enteral Ca and P intakes during the first 10 days of life. Infants (n = 109) with birth weights below 1500 g were randomly assigned to one of three groups that differed in the nutritional protocols delivered until day 10: Group A, mother’s own milk (MOM) and donor milk (unfortified); Group B, MOM (unfortified) and preterm formula; Group C, MOM (start fortification >50 mL/day) and preterm formula. Due to the earlier commencement of fortification, Group C received higher intakes of calcium and phosphorus and protein (p < 0.001) until day 10. At TCA weight, length, BMC and bone mineral density (BMD), measured by dual-X-ray absorptiometry, were not different between the groups. Nutritional intake of P was positively associated with length (β; (95% confidence interval (CI): 0.20 (0.001; 0.393); p-value = 0.048), whereas Ca intake was negatively associated with BMC (−1.94 (−2.78; −1.09); p-value < 0.001). A small interaction between Ca and P intake was only found for BMD (0.003 (0.00002; 0.00006); p-value = 0.036). The volume of human milk per kg provided during the first 10 days was positively associated with BMC (β; (95% CI): 0.013 (0.002; 0.023); p < 0.017). Higher intakes of Ca and P during the first 10 days, as provided in this study, did not improve bone mineralization at term corrected age.

Risk factors of metabolic bone disease of prematurity

OBJECTIVE

To identify the factors that increase risk of metabolic bone disease of prematurity (MBD).

STUDY DESIGN

A retrospective case-control study of infants born between January 2013-April 2014 with gestation age <30weeks and birth weight <1000g. MBD was defined as serum alkaline phosphatase above 500U/L and characteristic radiographic changes. Information was obtained on the presence of specific comorbidities.

RESULTS

Of 76 infants evaluated, 40 met criteria for MBD. Median gestational age was 25weeks in both groups (p=0.512). Median birth weight of infants with MBD was significantly lower than that of controls (560 vs. 765g, p<0.01). Longer period of parenteral nutrition and dexamethasone use was observed in MBD group. Cholestasis was associated with the highest likelihood of MBD (OR 16.6, 95% CI 4.8-56.9). Seizures (OR 5.2, 95% CI 1.3-20.5) and the prolonged use of diuretics (OR 2.6, 95% CI 1.0-7.0) also significantly increased the likelihood of MBD. Only cholestasis remained significant (OR 9.6, 95% CI 2.1-45.3) after multiple regression analysis.

CONCLUSION

Cholestasis is a significant risk factor for the development of MBD. Our future studies will be directed towards determining the causal relationship between cholestasis and MBD.

Metabolic bone disease in preterm infants: Relationship between radiologic grading in the wrist and serum biochemical markers

PURPOSE

To assess the relationship between radiographic findings of metabolic bone disease (MBD) and serum biochemical markers in preterm infants.

MATERIALS AND METHODS

A total of 159 preterm infants were included in this study. Two readers reviewed the wrist radiography for grading according to MBD severity. We recorded the levels of alkaline phosphatase (ALP) and phosphorous (P) immediately after birth, on the same day of the first wrist radiography (ALP-s, P-s), the highest/lowest ALP/P levels before the first wrist radiography (ALP-hb/P-lb) and during follow-up (ALP-h/P-l). For analysis, the patients were first subdivided into 4 groups according to MBD severity, and were then divided into 2 groups according to MBD presence or absence.

RESULTS

Of the 159 patients, 94, 39, 19, and 7 infants were classified into grades 0,1, 2, and 3. Analysis according to severity showed that ALP-s, ALP-hb, and ALP-h differed between grades 0-1 and 2-3 (all P<0.001); P-lb differed between grades 0 and 2 (P=0.001); and P-l differed between grades 0 and 2 or 3 (P<0.001 or P=0.001). Moreover, ALP-s, ALP-hb, ALP-h, P-s, P-lb, and P-l differed according to the presence or absence of MBD (P<0.001). ALP-h showed the largest area under the curve value (0.752, 95% confidence interval=0.676-0.828, P<0.001). The optimal cut-off value of ALP-h was 473.5U/L. The sensitivity and specificity were 81.5% and 47.9%. ALP-h was measured at 6.9±5.3 weeks after birth.

CONCLUSION

Taking the wrist radiography with reference to an ALP level measured at around 6.9 weeks after birth could be helpful for screening of MBD in preterm infants, unless a fracture is clinically suspected.

Assessment of Adequacy of Supplementation of Vitamin D in Very Low Birth Weight Preterm Neonates: A Randomized Controlled Trial

OBJECTIVES

To compare the effect of 400 IU and 1000 IU vitamin D for 6 weeks in very low birth weight preterm neonates.

DESIGN

Randomized, double-blinded controlled trial in a teaching hospital.

PARTICIPANTS

Fifty very low birth weight preterm neonates.

INTERVENTION

Vitamin D 400 IU/day (Group 1) or 1000 IU/day (Group 2).

OUTCOME MEASURES

Change in serum calcium, phosphate, alkaline phosphatase (ALP), 25-hydroxy vitamin D (25-OHD), parathormone, incidence of skeletal hypomineralization and growth.

RESULTS

After 6 weeks of supplementation, the mean serum calcium and 25-OHD levels were significantly higher (p  <  0.001 each), while ALP and parathormone levels significantly lower (p  <  0.001 each) in group 2. Skeletal hypomineralization was lesser and growth better in group 2.

CONCLUSION

Vitamin D supplementation in a dose of 1000 IU/day is more effective in maintaining serum calcium, phosphate, ALP, 25-OHD and parathormone levels with lower incidence of skeletal hypomineralization and better growth.

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.

Postnatal Changes in Humerus Cortical Bone Thickness Reflect the Development of Metabolic Bone Disease in Preterm Infants

Objective. To use cortical bone thickness (CBT) of the humerus to identify risk factors for the development of metabolic bone disease in preterm infants. Methods. Twenty-seven infants born at <32 weeks of gestational age, with a birth weight of <1,500 g, were enrolled. Humeral CBT was measured from chest radiographs at birth and at 27-28, 31-32, and 36-44 weeks of postmenstrual age (PMA). The risk factors for the development of osteomalacia were statistically analyzed. Results. The humeral CBT at 36-44 weeks of PMA was positively correlated with gestational age and birth weight and negatively correlated with the duration of mechanical ventilation. CBT increased with PMA, except in six very early preterm infants in whom it decreased. Based on logistic regression analysis, gestational age and duration of mechanical ventilation were identified as risk factors for cortical bone thinning. Conclusions. Humeral CBT may serve as a radiologic marker of metabolic bone disease at 36-44 weeks of PMA in preterm infants. Cortical bones of extremely preterm infants are fragile, even when age is corrected for term, and require extreme care to lower the risk of fractures.

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.

Assessment of the place of tubular reabsorption of phosphorus in the diagnosis of osteopenia of prematurity

AIM

In this study, we aimed to investigate the utility of tubular reabsorption of phosphorus in the diagnosis of osteopenia of prematurity in addition to biochemical markers.

MATERIALS AND METHOD

Premature babies with a gestational age of ≤32 weeks and/or a birth weight of ≤1 500 g who were hospitalized in the neonatal intensive care unit between June 2009 and March 2011 were included in the study. These babies were evaluated at the 40th gestational week and serum calcium, phosphorus, alkaline phosphatase, urea, creatinine, urinary calcium and phosphorus levels were measured and tubular reabsorption of phosphorus was determined. The subjects who had bone graphy findings and/or an alkaline phosphatase level of >400IU/L and a phosphorus value of <3.5 mg/dL were considered osteopenic. The levels of tubular reabsorption of phosphorus of the osteopenic patients were compared with the ones of the non-osteopenic patients. The study was initiated after obtaining ethics committee approval (date: 04.29.2009/213).

RESULTS

During the study period, a total of 698 premature babies were hospitalized in our neonatology unit. A diagnosis of osteopenia of prematurity was made in 24 of 190 subjects who met the study criteria. The level of tubular reabsorption of phosphorus was compared with the serum calcium, phosphorus and alkaline phosphatase levels measured at the 40th gestational week and alkaline phosphatase was found to be significantly increased in the group with a high tubular reabsorption of phosphorus (≥%95). When the subjects with a phosphorus level of <3.5 mg/dL and an alkaline phosphatase level of >499 IU were compared with the newborns who were found to have a tubular reabsorption of phosphorus of ≥%95 for the objective of evaluating the specificity and sensitivity of tubular reabsorption of phosphorus, the sensitivity, specificity, positive predictive value and negative predictive value of tubular reabsorption of phosphorus in the diagnosis of osteopenia were found to be 27%, 82%, 17% and 89%, respectively. When the osteopenic and non-osteopenic patients were compared in terms of the levels of tubular reabsorption of phosphorus, no statistically significant difference was found.

CONCLUSIONS

It was thought that it was not appropriate to use tubular reabsorption of phosphorus alone in the diagnosis of osteopenia of prematurity.

Comparing the Effects of Two Feeding Methods on Metabolic Bone Disease in Newborns with Very Low Birth Weights

Introduction:

Bone metabolic disease is an important issue in newborns with very low birth weight. The 80 percent of the transport of calcium (Ca) and phosphor (P) from mother to fetus takes place in the third trimester of pregnancy. This transport process is impaired with the preterm delivery of the newborn. On the other side, breast milk and formula are not competent resources to supply sufficient amounts of Ca and P to meet the requirements of the preterm newborn, thereby a greater reduction in the storage of these minerals. The current study has been done with the purpose of comparing the effects of two feeding methods on the indices of metabolic bone disease in newborns with very low birth weights (VLBW).

Materials and Methods:

The study design was cohort and the study was done on a total of 58 newborns with very low birth weights in Kashan Shahid Beheshti Hospital. The newborns were divided into two groups with 29 placed in the group of alternate feeding on preterm formula (preNan) and the other 29 placed in the group of breast milk and preterm formula (preNan). Eventually, the indices of bone metabolic disease were measured in both groups and were statistically analyzed.

Results:

The difference between the mean serum levels of Ca in different weeks and also between the two groups were significant (p=0.001). However, the changes in mean serum level of P in the two groups were not significant (P=0.151). The comparison of serum levels of alkaline phosphatase between the two groups indicated that their difference was significant and that they had been influenced by the feeding method (P=0.001). The serum level of bicarbonate, when compared between the two groups, was found to make a significant difference (P=0.001). The difference between the two feeding methods in precipitating rickets and osteopenia was not significant.

Conclusion:

According to the findings of current study, feeding on preterm formula (preNan) is associated with better and more desirable results, though the occurrence of rickets in the two groups had no significant difference.

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.

Vitamin D and skeletal growth and development

Vitamin D is critical to bone mineral metabolism and to the growth and development of the skeleton. Optimizing vitamin D status could be one of the cornerstones to optimize skeletal growth and achieving the maximum peak bone mass soon after the completion of adolescence. Maximizing peak bone mass is considered to be the key to primary prevention of osteoporosis. There is controversy, however, about what constitutes a healthy vitamin D status based on the most abundant circulating metabolite of vitamin D, namely 25 hydroxyvitamin D (25 OHD) in plasma or serum; and even the value of 25 OHD that should be used to define vitamin D deficiency. We reviewed the recent data on circulating 25 OHD concentrations and its relationship with skeletal growth in apparently healthy children and in those with nutritional vitamin D deficiency.

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

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

Selected macro/micronutrient needs of the routine preterm infant

Requirements for optimal nutrition, especially for micronutrients, are not well defined for premature infants. The "reference fetus," developed by Ziegler et al,(1) has served as a model to define nutritional needs and studies designed to determine nutrient requirements. Revision of nutrient requirements and provision of optimal nutrition may lead to improved outcomes in preterm infants. Appropriate provision of nutrients also may help prevent nutritional disorders, such as metabolic bone disease and anemia. In this review, we discuss calcium, phosphorus, magnesium, vitamin D, iron, and copper, and define optimal intakes based on the available published data.

Parathyroid hormone levels in neonates with suspected osteopenia

AIM

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

Detecting rickets in premature infants and treating them with calcitriol: experience from two cases

A premature infant is a baby born before 37 weeks of gestation. Rickets is a bone disease characterized by growth retardation due to the expansion of the hypertrophic chondrocyte layer of the growth plate and a failure to mineralize bone. Consequently, the bone is soft and permits marked bending and distortion. Although the incidence of rickets in preterm infants is lower due to improvements in health care and nutrition, there are still infants at high risk for this disease. However, few reports are available regarding the treatment of rickets in premature infants. Furthermore, published case studies on experiences with using calcitriol as a potential therapeutic for rickets in premature infants are very rare. Herein, we describe the detection of rickets in premature infants and our experience with calcitriol treatment in two premature infants. We recommended the use of oral calcitriol at a dose of 0.03-0.125 μg/kg/day, in addition to an appropriate formula that provides an adequate amount of calcium and phosphate intake. One patient was prescribed calcitriol for 40 days and the other for 37 days. The two infants gradually recovered and were discharged without any obvious side effects. It is recommended that alkaline phosphatase levels be monitored within 1 month after birth in premature infants with a birth weight of <1000 g. Infants presenting with high alkaline phosphatase levels are candidates for a long bone survey.

The validity of biochemical markers in metabolic bone disease in preterm infants: a systematic review

To establish the validity of biochemical markers of metabolic bone disease (MBD) in preterm infants.

CONCLUSION

There is insufficient evidence that any of the frequently used serum measurements are valid biochemical markers of MBD in preterm infants. Increased urinary calcium concentration may be a valid biochemical marker, but more research is necessary to confirm this.

Serial measurements of serum alkaline phosphatase for early prediction of osteopaenia in preterm infants

AIM

Osteopaenia commonly occurs in preterm infants; however, its diagnosis is often delayed when based on radiological findings. The aim of this study was to examine whether serial measurements of bone turnover markers are useful for early prediction of osteopaenia in preterm infants.

METHODS

Premature infants of ≤ 34 weeks gestation were enrolled. Serum alkaline phosphatase (ALP), bone form ALP (BALP), calcium and inorganic phosphate were concurrently measured biweekly from 3 weeks post-natal age until 40 weeks post-conceptional age. Radiographic examination of the forearm was performed at term age. Osteopaenia was defined as positive radiographic findings according to Koo's criteria.

RESULTS

Of the 46 premature infants completing the follow-up study at term age, 18 showed osteopaenia in radiographic examination. Serum ALP was highly correlated with BALP (R(2) = 0.93, P < 0.001). Infants who had osteopaenia showed a higher level of ALP and BALP after 3 weeks post-natal age than those who had no osteopaenia. ALP concentration exceeding 700 IU/L at 3 weeks post-natal age was predictive of osteopaenia at term age (sensitivity 73% and specificity 73%) and so did for the predictive value of BALP concentration exceeding 95 ug/L (sensitivity 73% and specificity 80%). BALP measures provided no greater benefit of diagnostic performance than ALP in early detection of osteopaenia. Furthermore, premature infants with osteopaenia showed similar levels of calcium and inorganic phosphatase concentration compared with those without.

CONCLUSION

Serum ALP concentration exceeding 700 IU/L at 3 weeks post-natal age can predict the risk of osteopaenia in preterm infants.

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®.

High frequencies of elevated alkaline phosphatase activity and rickets exist in extremely low birth weight infants despite current nutritional support

Background

Osteopenia and rickets are common among extremely low birth weight infants (ELBW, <1000 g birth weight) despite current practices of vitamin and mineral supplementation. Few data are available evaluating the usual course of markers of mineral status in this population. Our objectives in this study were to determine the relationship between birth weight (BW) and peak serum alkaline phosphatase activity (P-APA) in ELBW infants and evaluate our experience with the diagnosis of rickets in these infants.

Methods

We evaluated all ELBW infants admitted to Texas Children's Hospital NICU in 2006 and 2007. Of 211 admissions, we excluded 98 patients who were admitted at >30 days of age or did not survive/stay for >6 weeks. Bone radiographs obtained in 32 infants were reviewed by a radiologist masked to laboratory values.

Results

In this cohort of 113 infants, P-APA was found to have a significant inverse relationship with BW, gestational age and serum phosphorus. In paired comparisons, P-APA of infants <600 g (957 ± 346 IU/L, n = 20) and infants 600–800 g (808 ± 323 IU/L, n = 43) were both significantly higher than P-APA of infants 800–1000 g (615 ± 252 IU/L, n = 50), p < 0.01. Thirty-two patients had radiographic evaluation for evidence of rickets, based on P-APA greater than 800 IU/L, parenteral nutrition greater than 3 to 4 weeks, or clinical suspicion. Of these, 18 showed radiologic rickets and 14 showed osteopenia without rickets. Infants with BW <600 g were more likely to have radiologic rickets (10/20 infants) compared to those with BW 600–800 g (6/43 infants) and BW 800–1000 g (2/50 infants), p < 0.01 for each. P-APA was not significantly higher in infants with radiologic rickets (1078 ± 356 IU/L) compared to those without radiologic evidence of rickets (943 ± 346, p = 0.18).

Conclusion

Elevation of P-APA >600 IU/L was very common in ELBW infants. BW was significantly inversely related to both P-APA and radiologic rickets. No single value of P-APA was related to radiological findings of rickets. Given the very high risk of osteopenia and rickets among ELBW infants, we recommend consideration of early screening and early mineral supplementation, especially among infants <600 g BW.

Relationship of tibial speed of sound and lower limb length to nutrient intake in preterm infants

BACKGROUND

Metabolic bone disease of prematurity is characterised by impaired postnatal mineralisation of the rapidly growing infant skeleton.

OBJECTIVE

To longitudinally evaluate postnatal changes in tibial speed of sound (tSOS; which reflects cortical thickness and bone mineral density) and lower limb length (LLL; a measure of tibial growth) in very low birthweight preterm infants receiving contemporary neonatal care.

METHODS

tSOS and LLL were measured using a quantitative ultrasound device and an electronic neonatal knemometer, respectively, in the same limb, weekly, for a median period of four weeks (3-16 weeks) in 84 preterm infants (median gestation 26.8 weeks (range 23-35.2 weeks) and median birth weight 869.5 g (range 418-1481 g)).

RESULTS

Initial tSOS and LLL were correlated with gestation (r = 0.42, p<0.001; r = 0.76, p<0.001, respectively) and birth weight (r = 0.23, p = 0.038; r = 0.93, p<0.001, respectively). Postnatally, tSOS decreased (r = -0.15, p = 0.011) whereas LLL increased (r = 0.96, p<0.001) with age. The rate of postnatal change in LLL, but not in tSOS, was positively influenced by intake of calcium (p = 0.03), phosphorus (p = 0.01) and vitamin D (p = 0.03).

CONCLUSIONS

The postnatal decline in tSOS, which is probably due to cortical thinning secondary to endocortical bone loss, and increase in LLL provide new insight into the development of long bones in preterm infants.

Influence of genetic polymorphisms on bone disease of preterm infants

Bone disease is an important complication among very low birth weight (VLBW, <1500 g) infants. In adults, osteoporosis is associated with polymorphisms of vitamin D receptor (VDR), estrogen receptor (ER), and collagen Ialpha1 (COLIA1) genes. However, limited information is available regarding the role of these polymorphisms in bone disease in premature infants. We have investigated the possible association between bone disease and the allelic polymorphisms of these three genes in 65 VLBW infants. Twenty infants (30.8%) were diagnosed with bone disease based on high activity of bone formation (serum alkaline phosphatase and osteocalcin), bone resorption (urinary excretion of calcium and pyridinium crosslink) markers, and positive radiologic signs. Statistically significant correlation between thymine-adenine repeat [(TA)(n)] allelic variant of ER gene and bone disease was observed. Infants without bone disorder more often carried a high number of repeats [(TA)(n) >18] [odds ratio (OR): 0.17, 95% confidence interval (CI): 0.05-0.55]. A low number of repeats [(TA)(n) <19] was found more frequently in infants suffering from bone disease (OR: 6.00, 95% CI: 1.77-20.31). Significant interaction (p = 0.009) between VDR and COLIA1 genotypes was observed. In a logistic regression model, bone disorder of preterms significantly correlated with male gender (p = 0.002), lower gestational age (p = 0.015), homozygous allelic variants of high number of (TA)(n) repeats (p = 0.006), and interaction between VDR and COLIA1 genotype (p = 0.009).

Calcium nutrition and metabolism during infancy

Calcium is a vital mineral for the developing newborn infant. This review discusses perinatal and neonatal calcium metabolism, with an emphasis on enteral calcium absorption and the nutritional factors affecting calcium bioavailability including the three major endocrine hormones involved in calcium metabolism: parathyroid hormone, vitamin D, and calcitonin. The placenta transports calcium to the fetus throughout pregnancy, with the largest amount of fetal calcium accumulation occurring in the third trimester. At birth, the newborn transitions to intestinal absorption to meet the body's calcium needs. Most calcium is absorbed by paracellular passive diffusion in the small intestine. Calcium intestinal absorption is affected by the type and amount of calcium ingested. It is also affected by the amount of intestinal calcium that is bound to dietary fats and proteins. One major consequence of decreased calcium absorption is metabolic bone disease in which there is a failure of complete mineralization of the bone osteoid.

Role of plasma and urinary calcium and phosphorus measurements in early detection of phosphorus deficiency in very low birthweight infants

AIM

To analyse the role of serum and urinary calcium and phosphorus levels in early detection of mineral deficiency in very low birthweight (VLBW) infants born appropriate (AGA) and small for gestational age (SGA).

METHODS

64 VLBW infants were included in a cohort study and divided into two groups: AGA (n = 30) and SGA infants (n = 34). Then, they were divided according to the presence of radiological signs of metabolic bone disease (MBD): with MBD (n = 21) and without MBD (n = 34). Blood samples and 6 h urine collections were obtained for calcium, phosphorus, alkaline phosphatase activity and creatinine determinations between 3 and 5 wk of life.

RESULTS

There were no biochemical differences between AGA and SGA. Higher values of urinary calcium (MBD = 31.9 +/- 20.2, without MBD = 19.8 +/- 15.4; p = 0.017), calciuria (MBD = 2.3 +/- 0.3, without MBD = 1.4 +/- 0.8; p = 0.037) and alkaline phosphatase activity (MBD = 369 +/- 114, without MBD = 310 +/- 93; p = 0.04) were found in infants who developed MBD. Both groups showed high tubular phosphorus reabsorption indicating mineral deficiency.

CONCLUSION

Serum calcium and phosphorus levels are not good markers in early detection of mineral deficiency. However, the monitoring of calcium urinary levels may be helpful in early detection of mineral deficiency.

Bone mineralisation in premature infants cannot be predicted from serum alkaline phosphatase or serum phosphate

BACKGROUND

The bone mineral content of premature infants at term is lower than in mature infants at the same postconceptional age. Serum alkaline phosphatase and serum phosphate are often used as indicators of bone mineralisation.

OBJECTIVE

To analyse the association between bone mineral content and serum alkaline phosphatase and serum phosphate.

METHODS

Serum alkaline phosphatase and phosphate were measured at weekly intervals during admission in 108 premature infants of gestational age below 32 weeks (mean (SD) gestational age 29 (2) weeks; mean (SD) birth weight 1129 (279) g). Bone mineral content was measured at term (mean gestational age 41 weeks) by dual energy x ray absorptiometry and corrected for body size.

RESULTS

Serum alkaline phosphatase was significantly negatively associated with serum phosphate (p < 0.001). Bone mineral content was not associated with mean serum alkaline phosphatase (p = 0.8), peak serum alkaline phosphatase (p = 0.5), or mean serum phosphate (p = 0.2) at term.

CONCLUSION

Routine measurements of serum alkaline phosphatase and serum phosphate are of no use in predicting bone mineralisation outcome in premature infants.