Perinatal serum bone Gla-protein and vitamin D metabolites in preterm and fullterm neonates

Parathyroid hormone-vitamin D dynamics vary according to the definition of vitamin D deficiency in newborn infants

BACKGROUND

Parathyroid hormone (PTH) is an indirect functional indicator of vitamin D status. Risk of vitamin D deficiency, assessed using circulating 25-hydroxyvitamin D (25(OH)D), is defined as <30 nmol/L by the National Academy of Medicine and alternatively <25 nmol/L in the global consensus recommendation on prevention and management of nutritional rickets.

OBJECTIVE

To test PTH concentrations and the odds for elevated values according to vitamin D deficiency cut-points (<30 nmol/L, or <25 nmol/L) in newborn infants.

METHODS

Healthy term-born infants (n = 858) were recruited from Montreal, Canada (2016-2019). Obstetric data were obtained from medical records, and demographic factors surveyed. Immunoassays were used to measure newborn (24-36 h) serum PTH and 25(OH)D; 25(OH)D was standardized to National Institute of Standards and Technology (NIST) standard reference materials. Serum PTH was log-transformed before comparing serum 25(OH)D groups (<30 vs. ≥30; or <25 vs. ≥25 nmol/L) using ANCOVA adjusted for infant sex, type of delivery, parity, race, and family income. The odds of elevated PTH (>71.48 pg/mL) were tested using logistic regression, adjusted for the same covariates.

RESULTS

Infants (50.2 % female) were 39.6 ± 1.0 weeks gestational age (mean ± SD), and 3.41 ± 0.38 kg. Median serum 25(OH)D was 45.4 (IQR 23.2) nmol/L; 20.5 % had serum 25(OH)D < 30 nmol/L, and 12.4 % <25 nmol/L. Median serum PTH was 30.72 (IQR 33.90) pg/mL, elevated in 12.7 % overall, and higher in infants born with serum 25(OH)D < 25 vs. ≥25 nmol/L (35.96 (IQR 39.20) vs. 30.36 (IQR 32.93) pg/mL, p = 0.0158). The odds of elevated PTH were higher when serum 25(OH)D was <25 nmol/L (ORadj 2.13, 95 % CI: 1.23, 3.69). PTH concentration and the odds of being elevated did not differ according to the 30 nmol/L cut-point.

CONCLUSIONS

Based on this study, the definition of vitamin D deficiency relative to bone health as set by the National Academy of Medicine (<30 nmol/L) exceeds the threshold at which PTH is elevated in newborn infants.

Prevalence of Vitamin D Deficiency in a Large Newborn Cohort from Northern United States and Effect of Intrauterine Drug Exposure

Vitamin D is not only a vital element in bone health but is also a prohormone. Data regarding distribution of vitamin D status among preterm and term neonates in the United States are limited. There are no data on the effect of intrauterine drug exposure on vitamin D status. Our objective was to determine the distribution of vitamin D levels among preterm and term neonates and the effect of intrauterine illicit drug exposure. We did a retrospective chart review of neonates admitted from 2009 to 2016 to our neonatal intensive care unit with serum 25-hydroxycholecalciferol (25[OH]D) levels measured during the hospital stay. Of 1517 neonates, the median 25[OH]D level was 19 ng/mL with 31% deficient and 49% insufficient, even though 75% of mothers took prenatal vitamins. In pregnant women, 38% were vitamin-D-deficient and 44% were vitamin-D-insufficient. Four hundred seventy-one neonates had intrauterine drug exposure, with a median 25[OH]D level of 22.9 ng/mL versus 17.8 ng/mL in nonexposed neonates (p = 0.001). Despite maternal prenatal vitamin intake, neonates are at risk of vitamin D deficiency. Maternal illicit drug use was not related to lower 25[OH]D levels in neonates.

Evaluation of vitamin D3 levels and morphotic parameters of blood in prematurely born children at six years of age

In Poland the preterm children, with the birth rate reaching 6.3%, constitute a serious medical problem. The system of specialistic clinics provides them with the multidisciplinary care for the first 3 years of life, including the monitoring of hematologic parameters in relation with anemia and osteopenia. The aim of this study was to assess the vitamin D3 level and morphotic parameters of blood in children who were prematurely born at the time when they are about to start school. The study was carried out in a group of 92 children, aged 6 years ±0.63, including 54 preterm children born at gestational age <32 weeks - and 38 full-term children. A basic anthropometric measures and assessment of morphotic parameters and the vitamin D3 level were assessed. Statistical analyses were carried out using Shapiro-Wilk W-test, Student's t-test and Mann-Whitney U test. Preterm children had significantly lower the vitamin D3 level than controls. This also refers to some morphotic parameters of blood, such as level of hemoglobin, mean corpuscular hemoglobin concentration and platelets. Prematurely born 6-7 year-old children have significantly lower vitamin D3 levels in blood serum than normal and significantly lower hemoglobin levels than full-term children.

Maternal vitamin D supplementation during pregnancy

Introduction

Maternal vitamin D status in pregnancy has been linked to many health outcomes in mother and offspring. A wealth of observational studies have reported on both obstetric outcomes and complications, including pre-eclampsia, gestational diabetes, mode and timing of delivery. Many foetal and childhood outcomes are also linked to vitamin D status, including measures of foetal size, body composition and skeletal mineralization, in addition to later childhood outcomes, such as asthma.

Sources of data

Synthesis of systematic and narrative reviews.

Areas of agreement and controversy

The findings are generally inconsistent in most areas, and, at present, there is a lack of data from high-quality intervention studies to confirm a causal role for vitamin D in these outcomes. In most areas, the evidence tends towards maternal vitamin D being of overall benefit, but often does not reach statistical significance in meta-analyses.

Growing points and areas timely for developing research

The most conclusive evidence is in the role of maternal vitamin D supplementation in the prevention of neonatal hypocalcaemia; as a consequence the UK department of health recommends that pregnant women take 400 IU vitamin D daily. High-quality randomized placebo-controlled trials, such as the UK-based MAVIDOS trial, will inform the potential efficacy and safety of vitamin D supplementation in pregnancy across a variety of outcomes.

Detection of Ostecalcin in gingival Crevicular fluid in a Group of Orthodontic Patients

Aim:

To detect osteocalcin (OC) in gingival crevicular fluid (GCF) and to monitor the concentration of OC at what stage inflammation and bone resorption reaches their maximum following orthodontic activation.

Materials and Methods:

GCF samples were collected from six adult orthodontic patients (mean age = 22.3, range 20–24 years) on 3, 7, 10, 14, 21, 28, and 35 days after activation of orthodontic appliance, from the tooth surface where bone resorption was expected to occur. A total of 330 GCF sample were collected using filter paper strip, the volume measured by weighing. OC was analyzed using Enzyme-Linked immunoassay technique. Data were analyzed using the Statistical Package for Social Sciences software, SPSS (SPSS Inc., Chicago, IL, USA) version 15.

Results:

An increase in GCF volume and flow rate was noted in the 10^th day after activation of the orthodontic appliance activation; however, due to high-standard deviation, the result was not significant. OC was detected in all GCF samples. The amount and concentration were quite variable. Increase in the amount of OC was observed between days 7 and 14.

Conclusion:

OC was detected in all samples. The quantity of OC increased at day 10 in a number of samples. There was no obvious association between OC concentration and time of collection.

ENDOCRINOLOGY IN PREGNANCY: Influence of maternal vitamin D status on obstetric outcomes and the fetal skeleton

Vitamin D status has been increasingly associated with wide-ranging clinical outcomes. There is now a wealth of observational studies reporting on its associations with obstetric complications, including pre-eclampsia, gestational diabetes and the mode and timing of delivery. The findings are inconsistent, and currently there is a lack of data from high-quality intervention studies to confirm a causal role for vitamin D in these outcomes. This is similarly true with regards to fetal development, including measures of fetal size and skeletal mineralisation. Overall, there is an indication of possible benefits of vitamin D supplementation during pregnancy for offspring birthweight, calcium concentrations and bone mass as well as for reduced maternal pre-eclampsia. However, for none of these outcomes is the current evidence base conclusive, and the available data justify the instatement of high-quality randomised placebo controlled trials in a range of populations and health care settings to establish the potential efficacy and safety of vitamin D supplementation to improve particular outcomes.

Vitamin D status among preterm and full-term infants at birth

BACKGROUND

Risk factors for maternal vitamin D deficiency and preterm birth overlap, but the distribution of 25-hydroxyvitamin D (25(OH)D) levels among preterm infants is not known. We aimed to determine the associations between 25(OH)D levels and gestational age.

METHODS

We measured umbilical cord plasma levels of 25(OH)D from 471 infants born at Brigham and Women's Hospital in Boston. We used generalized estimating equations to determine whether preterm (<37 wks' gestation) or very preterm (<32 wks' gestation) infants had greater odds of having 25(OH)D levels below 20 ng/ml than more mature infants. We adjusted for potential confounding by season of birth, maternal age, race, marital status, and singleton or multiple gestation.

RESULTS

Mean cord plasma 25(OH)D level was 34.0 ng/ml (range: 4.1-95.3 and SD: 14.1). Infants born before 32 wks' gestation had increased odds of having 25(OH)D levels below 20 ng/ml in unadjusted (odds ratio (OR): 2.2; 95% confidence interval (CI): 1.1-4.3) and adjusted models (OR: 2.4; 95% CI: 1.2-5.3) as compared with more mature infants.

CONCLUSION

Infants born in <32 wks' gestation are at higher risk than more mature infants for low 25(OH)D levels. Further investigation of the relationships between low 25(OH)D levels and preterm birth and its sequelae is thus warranted.

Urinary osteocalcin and serum pro-C-type natriuretic peptide predict linear catch-up growth in infants

Preterm (PT) infants are at risk of growth failure despite advanced early care and nutrition. In addition to poor weight gain, slow postnatal linear growth also is associated with adverse neurological outcome. Markers distinguishing infants at risk for impaired catch-up growth are needed. The aim of this longitudinal study was to determine the extent to which postnatal levels of circulating cartilage (serum pro-C-type natriuretic peptide [S-proCNP]) and urinary bone metabolic markers (urinary osteocalcin [MidOC] and two forms of C-terminal cross-linked telopeptide of type I collagen [U-α-CTX-I and U-β-CTX-I]) predict catch-up growth in infancy in 67 PT and 58 full-term (FT) infants. PT infants were significantly shorter than FT infants during the first 6 months of life, but no statistically significant difference was found at the corrected age of 14 months (M14). At the age of 3 months (M3), S-ProCNP and U-MidOC levels, but not U-α-CTX-I and U-β-CTX-I levels, correlated positively with prospective growth velocity from M3 to M14 (ρ = 0.460, p < 0.001 and ρ = 0.710, p < 0.001, respectively). In predicting slow linear growth (growth velocity at the lowest quartile), the area under the S-ProCNP ROC curve was 0.662 and that of U-MidOC 0.891. Thus, U-MidOC, and to lesser extent S-ProCNP at M3 are predictors of catch-up growth in infancy.

High prevalence of moderately severe vitamin D deficiency in preterm infants

BACKGROUND

  The recommended dose of vitamin D supplementation of preterm infants is based on data from populations in which severe vitamin D deficiency is uncommon and may be inadequate for infants in high risk population. However, data on vitamin D status of preterm infants in high-risk populations, such as Middle Eastern countries is scarce.

METHODS

  This study investigates the vitamin D status of Arab mothers and their preterm infants. Maternal serum and cord blood 25(OH)D, calcium (Ca), phosphorus (P) and alkaline phosphate (ALP) were measured at delivery. Serum 25(OH)D was measured by HPLC while the other biochemical parameters were measured by standard autoanalyzer.

RESULTS

  Thirty-four preterm infants were studied. The mean gestational age was 31.4 weeks and birth weight was 1667g. The median serum 25(OH)D of 17.0nmol/L in 28 mothers and 14.5nmol/L in 34 cord blood samples were low. The median maternal and cord blood Ca, P and ALP levels were within normal range. Fifteen (44%) of the infants had moderately severe vitamin D deficiency (serum 25 (OH)D levels <12.5nmol/L). The median serum 25(OH)D levels of mothers who had reportedly taken prenatal vitamin D supplementation and those who had not were similar (17.3 vs 16.3) nmol/L. The mean serum 25(OH)D levels among preterm infants in this study were low when compared to levels in Caucasians preterm infants on which the current vitamin D recommendations are based.

CONCLUSION

  The high prevalence of moderately severe vitamin D deficiency in Arab preterm infants provides a justification to investigate vitamin D requirement of preterm infants in this and other high-risk populations.

Perinatal bone turnover in term human neonates and the influence of maternal smoking

Bone turnover in neonates appears independently of the comparably low maternal bone turnover, but there is only sparse information on the effect of the in utero environment on fetal bone turnover. Postnatally, the resuming growth velocity and alterations in mineral homeostasis affect neonatal bone turnover. This study evaluated the relationship of bone marker concentrations to maternal and fetal auxological variables as well as maternal smoking and assessed the short-term change in bone markers during the first days of life. Serum markers of bone formation [osteocalcin and bone-specific alkaline phosphatase (BALP)] and bone resorption (C-terminal telopeptide of type I collagen) were measured in cord blood and at discharge (median d 3) in 69 healthy term neonates. Concentrations of BALP were significantly lower in neonates of smokers (n = 16) compared with nonsmokers (n = 53), both at birth (p = 0.013) and at discharge (p = 0.036). Both cord osteocalcin and BALP were negatively related to maternal weight and maternal body mass index. Maternal smoking and pregnancy weight gain were the predictors of cord BALP (r2 = 0.24; p < 0.001), whereas the mode of delivery best predicted cord C-terminal telopeptide of type I collagen levels (r2 = 0.19; p < 0.001). C-terminal telopeptide of type I collagen and osteocalcin increased significantly (p < 0.001) from birth to discharge, whereas BALP levels did not change significantly during the same period. Our results suggest that maternal smoking during pregnancy and maternal obesity may have a negative impact on fetal bone formation. The significant increase of osteocalcin and C-terminal telopeptide of type I collagen may result either from an increase in bone turnover or altered renal clearance.

Urinary excretion of cross-linked N-telopeptides of type 1 collagen to assess bone resorption in infants from birth to 1 year of age

OBJECTIVES

To evaluate noninvasively bone resorption in infants and more specifically, to assess the accuracy of urinary collagen type 1 cross-linked N-telopeptide (NTX) excretion normalized to creatinine (NTX/Cr) in a spot urine sample as a reflection of daily NTX production in infants and to compute normative values for NTX excretion from birth to 1 year of age.

METHODS

NTX/Cr values obtained from a single spot urine sample were compared with daily urinary NTX excretion and NTX/Cr obtained in 24-hour urine collected from 8 hospitalized infants. Normative values for NTX excretion were collated with a cross-sectional study in 70 healthy French infants (42 boys, 28 girls) aged 0 to 374 days (weight: 2700-11 340 g; length: 46-76.5 cm) and free of diseases or treatments that could influence growth, bone mineralization, or renal function.

RESULTS

NTX/Cr values from single spot urine sample were significantly and linearly correlated with both daily NTX excretion (r = 0.783) and daily NTX/Cr (r = 0.952). In healthy infants, NTX excretion is low at birth, increases dramatically and significantly during the first 10 days of life, remains significantly elevated for approximately 3 months, and then decreases progressively to return to values similar to that observed at birth by 1 year of age.

CONCLUSIONS

These data provide new insights regarding the use of spot urine analysis for assessing NTX excretion during the first year of life. The normative data demonstrate significant age-related variations in this marker, which probably reflect adaptation to extrauterine life and accelerated bone turnover in infancy and which should be considered for the interpretation of this noninvasive bone resorption marker in the clinical setting.

Perinatal metabolism of vitamin D

During pregnancy, maternal serum concentrations of 25-hydroxyvitamin D, the circulating form of vitamin D, correlate with dietary vitamin D intake. Maternal serum concentrations of 1,25-dihydroxyvitamin D, the hormonal circulating and active form of vitamin D, are elevated during pregnancy; 1,25-dihydroxyvitamin D is synthesized mainly by the decidual cells of the placenta and allows for increased calcium absorption. The fetus is entirely dependent on the mother for its supply of 25-hydroxyvitamin D, which is believed to cross the placenta. Hypocalcemia and increased parathyroid hormone secretion induce synthesis of 1,25-dihydroxyvitamin D after birth in both full-term and preterm neonates. Nevertheless, serum concentrations of 25-hydroxyvitamin D are a rate-limiting factor in the synthesis of 1,25-dihydroxyvitamin D. In vitamin D-replete infants, circulating 1,25-dihydroxyvitamin D concentrations are higher than those observed in older infants. In countries where dairy products are not routinely supplemented with vitamin D, maternal vitamin D supplementation during pregnancy is necessary. However, there is no indication for the use of pharmacologic doses of vitamin D or its metabolites in the perinatal period.

Vitamin metabolism and requirements in the micropremie

Vitamin metabolism and requirements are reviewed for the micropremie (1000 Pounds g birthweight), for parenteral and enteral feedings. Recommendations are presented in table format. Human milk fortifiers and special formulas for the preterm infant are reviewed. For parenteral nutrition, only MVI Pediatric is currently available in the United States. Two millimeters per kilogram is recommended for the micropremie as the most satisfactory method of providing supplemental vitamins in total parenteral nutrition solutions.

Fetal osteocalcin levels are related to placental 11 beta-hydroxysteroid dehydrogenase activity in humans

OBJECTIVE

Overexposure to glucocorticoids in utero reduces birth weight and, in animals, leads to persistent hypertension in the offspring. The fetus is normally protected from maternal glucocorticoids by placental 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) which catalyses the conversion of cortisol to inert cortisone. In adult humans, osteocalcin is a sensitive marker of glucocorticoid exposure. The aim of this study was to determine whether cord blood osteocalcin levels were related to the ability of placental 11 beta-HSD to inactivate maternal cortisol.

DESIGN

Cross-sectional study examining the relation between cord blood levels of osteocalcin and placental glucocorticoid metabolism at term.

PATIENTS

Twenty-one women attending for delivery at the Simpson Memorial Maternity Pavilion in Edinburgh had cord venous and arterial blood samples collected at delivery.

MEASUREMENTS

Cord plasma levels of osteocalcin, cortisol and cortisone were measured by radioimmunoassay and indices of placental 11 beta-HSD activity were calculated.

RESULTS

All indices of placental 11 beta-hydroxysteroid dehydrogenase activity correlated directly and significantly with cord blood osteocalcin levels. For cord blood osteocalcin and the placental 11 beta-HSD Activity Index, Pearson's r was +0.58, r2 = 0.33 and P < 0.02.

CONCLUSION

We conclude that term cord blood osteocalcin level reflects the effectiveness of placental glucocorticoid inactivation, and may be a marker for the development of adult hypertension.

1,25-Dihydroxyvitamin D3 and osteocalcin in maternal and fetal guinea pigs

Maternal and fetal 1,25-dihydroxyvitamin D3 (1,25(OH)2D3) and osteocalcin were measured in guinea pigs, to examine their potential use as animal models for fetal bone development and calcium homeostasis. Measurements were performed on days 42, 57 and 63 of gestation. Maternal serum total 1,25(OH)2D3 concentrations were increased only at the end of gestation (day 63). However, because the vitamin D binding protein (DBP) and albumin levels were decreased by 35-50% from day 42 onwards, the unbound 1,25(OH)2D3, calculated as the 1,25(OH)2D3/DBP molar ratio, was increased before day 63. Osteocalcin concentrations during gestation were 50-54% of levels found in nongravid animals. Fetal serum total 1,25(OH)2D3 concentrations were 20% of those in maternal guinea pigs. Since DBP levels were only 9-15% of maternal levels, the unbound 1,25(OH)2D3 was consistently higher in fetuses, from day 42 onwards. There was a rise in total and unbound 1,25(OH)2D3 between days 57 and 63 of fetal life. Osteocalcin concentrations were higher in fetal than in adult guinea pigs, and reached peak values on day 57 (1023 micrograms/l, i.e. 4.2 times higher than in adult female guinea pigs). Fetuses of guinea pigs that had received a restricted food supply for 14 days (days 49-63) had normal 1,25(OH)2D3 concentrations, but decreased osteocalcin concentrations compared with normal fetuses. The data obtained in fetal guinea pigs are comparable with those found in human fetuses, and suggest that the guinea pig may be a suitable model for studies on fetal bone and mineral development.

Disorders of calcium and phosphorus homeostasis

Calcium and phosphorus are, respectively, the fifth and sixth most abundant elements in the body; both play vital roles in a multitude of physiologic systems. Because the great bulk of these elements is found in the skeleton, a large part of the discussion of calcium and phosphorus metabolism focuses on skeletal disorders, the impact of which falls heavily on young children. This article reviews the physiology of calcium and phosphorus, the skeletal and systemic consequences of disorders of vitamin D nutrition and metabolism, and the metabolic bone disease of prematurity.