Metabolic bone disease of prematurity and secondary hyperparathyroidism

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.

Reference values of parathyroid hormone in very low birth weight infants

PURPOSE

The primary goal was to estimate reference values of parathyroid hormone (PTH) in very low birth weight infants without severe neonatal morbidity. A secondary objective was to assess the relationship between PTH serum levels and selected laboratory markers of bone metabolism.

METHODS

Ninety two infants with birth weight less than 1500 g met the inclusion criteria of the study. Serum levels of PTH, 25-hydroxyvitamin-D [25(OH)D], C3-epi-25(OH)D, total calcium, phosphorus, and alkaline phosphatase, and urinary levels of calcium, phosphorus, and creatinine were examined on day 14 and subsequently every 2 weeks until discharge.

RESULTS

Of the total 167 serum samples examined for PTH levels in infants without 25(OH)D deficiency the estimated range was 0.9-11.9 pmol/l (8.5-112.3 pg/mL). During the first month, no statistically significant correlation was observed between PTH level and that of 25(OH)D, C3-epimers of 25(OH)D, S-Ca, S-P, or ALP, nor with urinary excretion of calcium and phosphorus. From the second month of life, there was a moderately significant correlation between PTH and 25(OH)D (Rho = -0.40, P =< .001), between PTH and calcium/creatinine ratio (Rho = -0.56, P = < .001), and between PTH and phosphorus/creatinine ratio (Rho = 0.51, P = < .001).

CONCLUSIONS

The physiological range for PTH levels for preterm neonates without 25(OH)D deficiency was estimated as 0.9-11.9 pmol/l (8.5-112.3 pg/mL). It seems that elevation of serum PTH above this range can be considered as hyperparathyroidism in very low birth weight infants.

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.

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.

Outcomes into adulthood of infants born extremely preterm

As survival of infants born extremely preterm increases, more are now reaching adulthood. It is well documented that survivors born extremely preterm experience more developmental delay and disability in multiple domains compared with term-born controls in early childhood and school age. However, with increasing age, health problems involving physical and mental health become more evident. Despite these challenges, it is reassuring that self-reported quality of life remains good. Future directions of research include development of age-appropriate interventions to optimise health and development of individuals born extremely preterm beyond school age.

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.

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.

Impact of Diuretic Therapy in the Treatment of Bronchopulmonary Dysplasia and Acute Kidney Injury in the Neonatal Population

BACKGROUND

Diuretics are among the most frequently prescribed medications in the neonatal intensive care unit (NICU), despite minimal data regarding the safety and efficacy of their use in the neonatal population. Off-label diuretic therapy is used in preterm and full-term infants to both optimize kidney function and improve respiratory status.

PURPOSE

This article examines the literature specific to the impact of diuretic therapy in the NICU and compares the benefits versus risks of utilization as they pertain to the prevention and treatment of renal and pulmonary dysfunction in this population.

METHODS/SEARCH STRATEGY

A comprehensive literature search of online databases was performed, utilizing: CINAHL via EBSCO, PubMed, and ProQuest. Full-text, peer-reviewed, clinical trials, and review articles published in the English language between 2005 and 2015 were searched.

FINDINGS/RESULTS

Diuretics rank as the seventh most frequently prescribed medication in the NICU. More than 8% of all NICU patients and 37% of infants born at less than 32 gestational weeks and weighing less than 1500 g are exposed to diuretics. Benefits include lung fluid resorption acceleration, improved urine output, fluid retention counteraction, and augmentation of physiologic weight loss.

IMPLICATIONS FOR PRACTICE

Diuretics are currently utilized in the NICU at an alarming rate, without adequate clinical trials regarding their safety and efficacy of use.

IMPLICATIONS FOR RESEARCH

Updated studies are needed regarding short- and long-term outcomes of diuretic use, as well as overall general outcome data regarding the impact and evaluation of diuretic usage in the NICU population.

The Clinical and Biochemical Predictors of Bone Mass in Preterm Infants

BACKGROUND

Metabolic bone disease of prematurity still occurs in preterm infants, although a significant improvement in neonatal care has been observed in recent decades. Dual-energy X-ray absorptiometry (DXA) is the precise technique for assessing bone mineral content (BMC) in preterm infants, but is not widely available.

AIM

To investigate the clinical and biochemical parameters, including bone metabolism markers as potential predictors of BMC, in preterm infants up to 3 months corrected age (CA).

MATERIALS AND METHODS

Ca-P homeostasis, iPTH, 25-hydroxyvitamin D, osteocalcin, N-terminal propeptide, cross-linked C-telopeptide and amino-terminal pro C-type natriuretic peptide and the DXA scans were prospectively performed in 184 preterm infants (≤ 34 weeks' gestation) between term age and 3 mo CA. Lower bone mass was defined as BMC below or equal to respective median value for the whole study group, rounded to the nearest whole number.

RESULTS

The appropriate quality DXA scans were available for 160 infants (87%) examined at term and for 130 (71%) tested at 3 mo CA. Higher iPTH level was the only independent predictor of lower BMC at term, whereas lower BMC at 3 mo CA was associated both with lower urinary phosphate excretion and higher serum osteocalcin level. ROC analysis showed that iPTH >43.6 pg/mL provided 40% sensitivity and 88% specificity in identification of preterm infants with lower BMC at term. In turn, urinary phosphate excretion (TRP>97% or UP/Cr ≤0.74 mg/mg) and serum osteocalcin >172 ng/mL provided 40% sensitivity and 93% specificity in identification of infants with decreased BMC at 3 mo CA.

CONCLUSION

Serum iPTH might to be a simple predictor of reduced BMC in preterm infants at term age, but urinary phosphate excretion and serum osteocalcin might predict reduced BMC at 3 mo CA. These results represent a promising diagnostic tool based on simple, widely available biochemical measurements for bone mass assessment in preterm infants.

Screening for secondary hyperparathyroidism in preterm infants

BACKGROUND

The major cause of osteopathy of prematurity is dietary phosphate deficiency, but secondary hyperparathyroidism caused by calcium deficiency or vitamin D deficiency is also important. Because parathyroid hormone (PTH) mobilizes calcium and phosphate from the bone, hyperparathyroidism worsens osteopathy of prematurity. In order to identify useful markers to screen for and diagnose hyperparathyroidism in preterm infants, we measured serum and urinary biochemical markers.

METHODS

Several biomarkers, including serum intact PTH (iPTH), were measured in urine and serum samples obtained from 95 preterm infants, and the relationship between serum iPTH and the other parameters was analyzed.

RESULTS

Mean gestation was 33.2 ± 2.9 weeks, and mean birthweight was 1705 ± 402 g. Samples were collected around postnatal day 17.3 ± 7.4. Fourteen infants (14.7%) had iPTH >65 pg/mL. Cut-offs for serum alkaline phosphatase (ALP) and percent tubular reabsorption rate of phosphate (%TRP) were fixed at 1300 IU/L and 93%, respectively using receiver operating characteristic curves with iPTH cut-off of 65 pg/mL. Serum ALP was proven to be a good marker: ALP had a sensitivity of 78.6% and a specificity of 86.4%, while %TRP itself was not: %TRP had a sensitivity of 64.3% and a specificity of 58.0%. Combined measurement of serum ALP (>1300 IU/L) and %TRP (≤93%), however, had a specificity of 93.8% for detecting elevated iPTH.

CONCLUSION

Measurement of serum ALP (>1300 IU/L) is considered as an effective screening method to detect hyperparathyroidism. In addition, combined assessment of ALP(>1300 IU/L) and %TRP(≤93%) is a good indicator of elevated iPTH in 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.

Calcitriol treatment in metabolic bone disease of prematurity with elevated parathyroid hormone: A preliminary study

Objective

To describe the association of calcitriol treatment with the change in parathyroid hormone (PTH) and biochemical markers of bone disease in infants with metabolic bone disease of prematurity (MBD) and secondary hyperparathyroidism.

Study design

This retrospective chart review examined serum intact PTH, serum calcium (Ca), serum phosphorus (P), serum alkaline phosphatase (APA), urine calcium/creatinine (UCa/Cr), and tubular reabsorption of phosphate (TRP) in 32 infants prior to and following calcitriol treatment for MBD with PTH >100 pg/ml. 25-hydroxyvitamin D concentrations were recorded.

Results

Following calcitriol treatment, PTH decreased from median (min/max) 220 (115/593) to 25 (3/259) pg/ml, p < 0.001; Ca increased from 9.9 (8.9/10.7) to 10.3 (9.7/11.3) mg/dl, p < 0.001; P increased from 4.3 (2.7/6.4) to 5.4 (2.9/7.4) mg/dl, p = 0.001; and TRP increased from 81 (59/98) to 91.5 (78/98) %, p = 0.03. APA did not differ pre-treatment: 616 (209/1193) vs. post-treatment 485 (196/1229) U/L, p = 0.12. Vitamin D deficiency was not present. Hypercalcemia with hypercalciuria occurred in 3/32 subjects, all normalized after dose reduction.

Conclusion

Improvements in MBD markers and lack of serious adverse effects suggest calcitriol may be a treatment option in infants with MBD and secondary hyperparathyroidism.

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Calcitriol was associated with improvement in several MBD-related metabolic parameters

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PTH and TRP may be useful in evaluating MBD in neonates with intestinal compromise

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Markers of MBD were not different in early MBD vs MBD associated with fracture

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 of prematurity

Metabolic bone disease (MBD) of prematurity remains a significant problem for preterm, chronically ill neonates. The definition and recommendations for screening and treatment of MBD vary in the literature. A recent American Academy of Pediatrics Consensus Statement may help close the gap in institutional variation, but evidence based practice guidelines remain obscure due to lack of normative data and clinical trials for preterm infants. This review highlights mineral homeostasis physiology, current recommendations in screening and monitoring, prevention and treatment strategies, and an added perspective of a bone health team serving a high volume referral neonatal intensive care center.

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.