A phase II dose evaluation pilot feasibility randomized controlled trial of cholecalciferol in critically ill children with vitamin D deficiency (VITdAL-PICU study).

BACKGROUND: Vitamin D deficiency (VDD) is highly prevalent in the pediatric intensive care unit (ICU) and associated with worse clinical course. Trials in adult ICU demonstrate rapid restoration of vitamin D status using an enteral loading dose is safe and may improve outcomes. There have been no published trials of rapid normalization of VDD in the pediatric ICU. METHODS: We conducted a multicenter placebo-controlled phase II pilot feasibility randomized clinical trial from 2016 to 2017. We randomized 67 critically ill children with VDD from ICUs in Canada, Chile and Austria using a 2:1 randomization ratio to receive a loading dose of enteral cholecalciferol (10,000 IU/kg, maximum of 400,000 IU) or placebo. Participants, care givers, and outcomes assessors were blinded. The primary objective was to determine whether the loading dose normalized vitamin D status (25(OH)D > 75 nmol/L). Secondary objectives were to evaluate for adverse events and assess the feasibility of a phase III trial. RESULTS: Of 67 randomized participants, one was withdrawn and seven received more than one dose of cholecalciferol before the protocol was amended to a single loading dose, leaving 59 participants in the primary analyses (40 treatment, 19 placebo). Thirty-one/38 (81.6%) participants in the treatment arm achieved a plasma 25(OH)D concentration > 75 nmol/L versus 1/18 (5.6%) the placebo arm. The mean 25(OH)D concentration in the treatment arm was 125.9 nmol/L (SD 63.4). There was no evidence of vitamin D toxicity and no major drug or safety protocol violations. The accrual rate was 3.4 patients/month, supporting feasibility of a larger trial. A day 7 blood sample was collected for 84% of patients. A survey administered to 40 participating families showed that health-related quality of life (HRQL) was the most important outcome for families for the main trial (30, 75%). CONCLUSIONS: A single 10,000 IU/kg dose can rapidly and safely normalize plasma 25(OH)D concentrations in critically ill children with VDD, but with significant variability in 25(OH)D concentrations. We established that a phase III multicentre trial is feasible. Using an outcome collected after hospital discharge (HRQL) will require strategies to minimize loss-to-follow-up. CLINICALTRIALS: gov NCT02452762 Registered 25/05/2015.

Effect of Vitamin D Supplementation on Bone Mass in Infants With 25-Hydroxyvitamin D Concentrations Less Than 50 nmol/L: A Prespecified Secondary Analysis of a Randomized Clinical Trial.

Importance: The dose of supplemental vitamin D needed in infants born with serum 25-hydroxyvitamin D (25[OH]D) concentrations less than 50 nmol/L (ie, 20 ng/mL) is unclear. Objective: To determine whether a higher dose (1000 IU vs 400 IU per day) is required in infants born with 25(OH)D concentrations less than 50 nmol/L for bone mineral accretion across infancy. Design, Setting, and Participants: In this prespecified secondary analysis of a double-blinded randomized clinical trial, conducted from March 2016 to March 2019 in a single center in Greater Montreal, Quebec, Canada, a consecutive sample of 139 healthy term singletons were recruited from 866 infants screened for vitamin D status at birth. Data were analyzed from June 2021 to November 2022. Interventions: Capillary blood was collected 24 to 36 hours after birth to measure serum total 25(OH)D concentrations. Infants with 25(OH)D concentrations less than 50 nmol/L were randomized to receive either 1000 IU or 400 IU per day of oral vitamin D3 supplementation from age 1 to 12 months. Infants with 25(OH)D concentrations of 50 nmol/L or greater formed a reference group. Main Outcomes and Measures: Measures at age 1, 3, 6, and 12 months were preplanned and included whole-body bone mineral content, lumbar spine bone mineral content, and bone mineral density using dual-energy x-ray absorptiometry, and serum 25(OH)D3 using liquid chromatography tandem mass spectrometry. Results: Of 139 included infants, 81 (58.3%) were male, and the median (IQR) gestational age at birth was 39.6 (38.9-40.6) weeks. A total of 49 infants were included in the 1000 IU per day group, 49 infants in the 400 IU per day group, and 41 in the reference group. Mean (SD) whole-body bone mineral content was not different between trial groups over time (1000 IU per day, 173.09 [2.36] g; 400 IU per day, 165.94 [66.08] g). Similarly, no differences were observed in lumbar spine bone mineral content or density. Mean (SD) serum 25(OH)D3 concentrations were significantly higher in the 1000 IU per day group from age 3 to 12 months (3 months, 115.2 [35.3] nmol/L; 6 months, 121.6 [34.4] nmol/L; 12 months, 99.6 [28.8] nmol/L) compared with the 400 IU per day trial group (3 months, 77.4 [23.3] nmol/L; 6 months, 85.1 [18.6] nmol/L; 12 months, 82.3 [14.3] nmol/L). Conclusions and Relevance: In this study, a higher dose of vitamin D supplementation in infants born with 25(OH)D concentrations less than 50 nmol/L did not present advantages to bone mass in infancy. This study supports a standard dose of 400 IU per day of vitamin D supplementation for breastfed infants in Montreal. Trial Registration: ClinicalTrials.gov Identifier: NCT02563015.

Correction of neonatal vitamin D status using 1000 IU vitamin D/d increased lean body mass by 12 months of age compared with 400 IU/d: a randomized controlled trial.

BACKGROUND: Intrauterine exposure to maternal vitamin D status <50 nmol/L of serum 25-hydroxyvitamin D [25(OH)D] may adversely affect infant body composition. Whether postnatal interventions can reprogram for a leaner body phenotype is unknown. OBJECTIVES: The primary objective was to test whether 1000 IU/d of supplemental vitamin D (compared with 400 IU/d) improves lean mass in infants born with serum 25(OH)D <50 nmol/L. METHODS: Healthy, term, breastfed infants (Montréal, Canada, March 2016-2019) were assessed for serum 25(OH)D (immunoassay) 24-36 h postpartum. Infants with serum 25(OH)D <50nmol/L at 24-36 h were eligible for the trial and randomly assigned at baseline (1 mo postpartum) to 400 (29 males, 20 females) or 1000 IU/d (29 males, 20 females) of vitamin D until 12 mo. Infants (23 males, 18 females) with 25(OH)D ≥50 nmol/L (sufficient) formed a nonrandomized reference group provided 400 IU/d. Anthropometry, body composition (DXA), and serum 25(OH)D concentrations were measured at 1, 3, 6, and 12 mo. RESULTS: At baseline, mean ± SD serum 25(OH)D concentrations in infants allocated to the 400 and 1000 IU/d vitamin D groups were 45.8 ± 14.1 and 47.6 ± 13.4, respectively; for the reference group it was 69.2 ± 16.4 nmol/L. Serum 25(OH)D concentration increased on average to ≥50 nmol/L in the trial groups at 3-12 mo. Lean mass varied differently between groups over time; at 12 mo it was higher in the 1000 IU/d vitamin D group than in the 400 IU/d group (mean ± SD: 7013 ± 904.6 compared with 6690.4 ± 1121.7 g, P = 0.0428), but not the reference group (mean ± SD: 6715.1 ± 784.6 g, P = 0.19). Whole-body fat mass was not different between the groups over time. CONCLUSIONS: Vitamin D supplementation (400 or 1000 IU/d) during infancy readily corrects vitamin D status, whereas 1000 IU/d modestly increases lean mass by 12 mo. The long-term implications require further research. This trial was registered at clinicaltrials.gov as NCT02563015.

Vitamin D Status of Infants of Mothers with Gestational Diabetes: Status at Birth and a Randomized Controlled Trial of Vitamin D Supplementation across Infancy.

BACKGROUND: Vitamin D status and requirements of infants of women with gestational diabetes mellitus (GDM) are unclear. OBJECTIVES: The objectives were to assess vitamin D status in infants of mothers with GDM and compare vitamin D status in response to 400 vs. 1000 IU/d vitamin D supplementation in infants born with serum 25-hydroxyvitamin D [25(OH)D] <50 nmol/L. METHODS: Women with GDM delivering full-term infants (n = 98; March 2017-2019, Montreal, Canada) were surveyed for demographic and lifestyle factors. Pregnancy history was obtained from medical records. Newborn serum 25(OH)D was measured (immunoassay) and categorized as <30 (deficient) or ≥40 nmol/L (adequate). Breastfed neonates (n = 16) with serum 25(OH)D <50 nmol/L at birth were randomly assigned to 400 or 1000 IU/d of supplemental cholecalciferol (vitamin D3), and serum 25(OH)D was measured at baseline (≤1 mo) and 3, 6, and 12 mo of age. Groups were compared using a linear mixed-effects model and Tukey-Kramer post hoc tests. RESULTS: Mean newborn serum 25(OH)D was 46.4 (95% CI: 43.9, 49.9) nmol/L, with 15.3% (95% CI: 8.2%, 22.4%) <30 nmol/L and 61.2% (95% CI: 51.6%, 70.9%) ≥40 nmol/L. During the trial, most infants were breastfed to 3 mo (400 IU/d: 87.5%; 1000 IU/d: 75.0%). Mean (± SEM) infant serum 25(OH)D was higher in the 1000-IU/d group at 3 mo (79.9 ± 5.9 vs. 111.5 ± 15.2 nmol/L; P = 0.0263), and although not different at 6-12 mo, was maintained at >50 nmol/L. CONCLUSIONS: Most infants of women with GDM had adequate vitamin D status in this study. In those born with serum 25(OH)D <50 nmol/L, vitamin D status was corrected by 3 mo of age in response to 400 or 1000 IU/d of supplemental vitamin D. Dietary guidance should continue to recommend that all women who could become pregnant take a multivitamin supplement and that breastfed infants receive 400 IU/d of supplemental vitamin D. This study and ancillary trial were registered at clinicaltrials.gov (https://www. CLINICALTRIALS: gov/ct2/show/NCT02563015) as NCT02563015.

Comparison of two vitamin D supplementation strategies in children with sickle cell disease: a randomized controlled trial.

Previously, we showed that nearly 70% of children followed in our sickle cell disease (SCD) clinic were vitamin D- deficient and had low vitamin intake with poor use of supplements. We compared the change in serum 25-hydroxyvitamin D [25(OH)D], safety and clinical impact of two vitamin D supplementation regimens in children with SCD. Children (5-17 years, all genotypes) were randomized to a single bolus of vitamin D3 (300 000 IU; n = 18) or placebo (n = 20). All children received a prescription for daily 1 000 IU vitamin D3 . Serum 25(OH)D and calcium, urinary calcium/creatinine ratio, musculoskeletal pain, quality of life, haematology and bone markers were assessed at baseline and three months post intervention. Bolus administration led to a greater rise in 25(OH)D levels from baseline compared to placebo (20 ± 16 nmol/l vs. 2 ± 19 nmol/l; P = 0·003) and correction of vitamin D deficiency. No hypercalcaemia nor hypercalciuria occurred during the study, but more children in the bolus group experienced gastrointestinal symptoms within the first month (P = 0·04). There were no differences between groups for other outcomes. The use of a high-dose vitamin D bolus combined with daily 1 000 IU vitamin D3 was more efficient in raising 25(OH)D levels than daily supplementation alone in children with SCD.

Prevention of post-cardiac surgery vitamin D deficiency in children with congenital heart disease: a pilot feasibility dose evaluation randomized controlled trial.

BACKGROUND: The vast majority of children undergoing cardiac surgery have low vitamin D levels post-operative, which may contribute to greater illness severity and worse clinical outcomes. Prior to the initiation of a large phase III clinical trial focused on clinical outcomes, studies are required to evaluate the feasibility of the study protocol, including whether the proposed dosing regimen can safely prevent post-operative vitamin D deficiency in this high-risk population. METHODS: We conducted a two-arm, double-blind dose evaluation randomized controlled trial in children requiring cardiopulmonary bypass for congenital heart disease. Pre-operatively, participants were randomized to receive cholecalciferol representing usual care (< 1 year = 400 IU/day, > 1 year = 600 IU/day) or a higher dose approximating the Institute of Medicine tolerable upper intake level (< 1 year = 1600 IU/day, > 1 year = 2400 IU/day). The feasibility outcomes were post-operative vitamin D status (primary), vitamin D-related adverse events, accrual rate, study withdrawal rate, blinding, and protocol non-adherence. RESULTS: Forty-six children were randomized, and five withdrew prior to surgery, leaving 41 children (21 high dose, 20 usual care) in the final analysis. The high dose group had higher 25-hydroxyvitamin D concentrations both intraoperatively (mean difference + 25.9 nmol/L; 95% CI 8.3-43.5) and post-operatively (mean difference + 17.2 nmol/L; 95% CI 5.5-29.0). Fewer participants receiving high-dose supplementation had post-operative serum 25-hydroxyvitamin D concentrations under 50 nmol/L, compared with usual care (RR 0.31, 95% CI 0.11-0.87). Post-operative vitamin D status was associated with the treatment arm and the number of doses received. There were no cases of hypercalcemia, and no significant adverse events related to vitamin D. While only 75% of the target sample size was recruited (limited funding), the consent rate (83%), accrual rate (1.5 per site month), number of withdrawals (11%), and ability to maintain blinding support feasibility of a larger trial. CONCLUSIONS: Pre-operative daily high-dose supplementation improved vitamin D status pre-operatively and at time of pediatric ICU admission. The protocol for a more definitive trial should limit enrollment of children with at least 30 days between randomization and surgery to allow adequate duration of supplementation or consider a loading dose. TRIAL REGISTRATION: ClinicalTrials.gov, NCT01838447. Registered on April 24, 2013.

Impact of two oral doses of 100,000 IU of vitamin D3 in preschoolers with viral-induced asthma: a pilot randomised controlled trial.

BACKGROUND: New evidence supports the use of supplemental vitamin D in the prevention of exacerbation of asthma; however, the optimal posology to sufficiently raise serum levels while maximising adherence is unclear. The objective was to ascertain the efficacy of high-dose vitamin D3 in increasing serum vitamin D in preschoolers with asthma and provide preliminary data on safety and efficacy outcomes. METHODS: We conducted a 7-month, triple-blind, randomised, placebo-controlled, pilot trial of children aged 1-5 years with viral-induced asthma. Participants were allocated to receive two oral doses of 100,000 IU vitamin D3 (intervention) or identical placebo (control) 3.5 months apart, once in the fall and once in the winter. Serum 25-hydroxyvitamin D (25OHD) was measured by tandem mass spectrometry at baseline, 10 days, 3.5 months, 3.5 months + 10 days, and 7 months. The main outcome was the change in serum 25OHD from baseline (Δ25OHD) over time and at 3.5 and 7 months; other outcomes included the proportion of children with 25OHD ≥ 75 nmol/L, safety, and adverse event rates. RESULTS: Children (N = 47) were randomised (intervention, 23; control, 24) in the fall. There was a significant adjusted group difference in the Δ25OHD (95% confidence interval) of 57.8 (47.3, 68.4) nmol/L, p < 0.0001), with a time (p < 0.0001) and group*time interaction effect (p < 0.0001), in favour of the intervention. A significant group difference in the Δ25OHD was observed 10 days after the first (119.3 [105.8, 132.9] nmol/L) and second (100.1 [85.7, 114.6] nmol/L) bolus; it did not reach statistical significance at 3.5 and 7 months. At 3.5 and 7 months, respectively, 63% and 56% of the intervention group were vitamin D sufficient (≥ 75 nmol/L) compared to 39% and 36% of the control group. Hypercalciuria, all without hypercalcaemia, was observed in 8.7% of intervention and 10.3% of control samples at any time point. Exacerbations requiring rescue oral corticosteroids, which appear as a promising primary outcome, occurred at a rate of 0.87/child. CONCLUSION: Two oral boluses of 100,000 IU vitamin D3,once in the fall and once in the winter, rapidly, safely, and significantly raises overall serum vitamin D metabolites. However, it is sufficient to maintain 25OHD ≥ 75 nmol/L throughout 7 months in only slightly more than half of participants. TRIAL REGISTRATION: ClinicalTrials.gov, NCT02197702 (23 072014). Registered on 23 July 2014.

Vitamin D in the prevention of exacerbations of asthma in preschoolers (DIVA): protocol for a multicentre randomised placebo-controlled triple-blind trial.

INTRODUCTION: Preschoolers have the highest rate of emergency visits and hospitalisations for asthma exacerbations of all age groups, with most triggered by upper respiratory tract infections (URTIs) and occurring in the fall or winter. Vitamin D insufficiency is highly prevalent in Canadian preschoolers with recurrent asthma exacerbations, particularly in winter. It is associated with more URTIs and, in patients with asthma, more oral corticosteroid (OCS) use. Although evidence suggests that vitamin D supplements significantly decrease URTIs and asthma exacerbations requiring OCS, there is insufficient data in preschoolers. This study aims to determine the impact of vitamin D3 supplementation on exacerbations requiring OCS, in preschoolers with recurrent URTI-induced asthma exacerbations. METHODS AND ANALYSIS: This is a phase III, randomised, triple-blind, placebo-controlled, parallel-group multicentre trial of vitamin D3 supplementation in children aged 1-5 years, with asthma triggered by URTIs and a recent history of frequent URTIs and OCS use. Children (n=865) will be recruited in the fall and early winter and followed for 7 months. They will be randomised to either the (1) intervention: two oral boluses of 100 000 international unit (IU) vitamin D3 (3.5 months apart) with 400 IU vitamin D3 daily; or (2) control: identical placebo boluses with daily placebo. The primary outcome is the number of exacerbations requiring OCS per child, documented by medical and pharmacy records. Secondary outcomes include number of laboratory-confirmed viral URTIs, exacerbation duration and severity, parent functional status, healthcare use, treatment deintensification, cost and safety. ETHICS AND DISSEMINATION: This study has received ethical approval from all sites. Results will be disseminated via international conferences and manuscripts targeting paediatricians and respirologists, and to families of asthmatic children via our Quebec parents-partners outreach programme. If proven effective, findings may markedly influence the management of URTI-induced asthma in high-morbidity preschoolers and could be directly implemented into practice with an update to clinical guidelines. TRIAL REGISTRATION NUMBER: NCT03365687.

Study protocol for a phase II dose evaluation randomized controlled trial of cholecalciferol in critically ill children with vitamin D deficiency (VITdAL-PICU study).

BACKGROUND: Clinical research has recently demonstrated that vitamin D deficiency (VDD) is highly prevalent in the pediatric intensive care unit (PICU) and associated with worse clinical course. Multiple adult ICU trials have suggested that optimization of vitamin D status through high-dose supplementation may reduce mortality and improve other clinically relevant outcomes; however, there have been no trials of rapid normalization in the PICU setting. The objective of this study is to evaluate the safety and efficacy of an enteral weight-based cholecalciferol loading dose regimen in critically ill children with VDD. METHODS/DESIGN: The VITdAL-PICU pilot study is designed as a multicenter placebo-controlled phase II dose evaluation pilot randomized controlled trial. We aim to randomize 67 VDD critically ill children using a 2:1 randomization schema to receive loading dose enteral cholecalciferol (10,000 IU/kg, maximum of 400,000 IU) or a placebo solution. Participants, caregivers and outcome assessors will be blinded to allocation. Eligibility criteria include ICU patient, aged 37 weeks to 18 years, expected ICU length of stay more than 48 h, anticipated access to bloodwork at 7 days, and VDD (blood total 25 hydroxyvitamin D < 50 nmol/L). The primary objective is to determine whether the dosing protocol normalizes vitamin D status, defined as a blood total 25(OH)D concentration above 75 nmol/L. Secondary objectives include an examination of the safety of the dosing regimen (e.g. hypercalcemia, hypercalciuria, nephrocalcinosis), measures of vitamin D axis function (e.g. calcitriol levels, immune function), and protocol feasibility (eligibility criteria, protocol deviations, blinding). DISCUSSION: Despite significant observational literature suggesting VDD to be a modifiable risk factor in the PICU setting, there is no robust clinical trial evidence evaluating the benefits of rapid normalization. This phase II clinical trial will evaluate an innovative weight-based dosing regimen intended to rapidly and safely normalize vitamin D levels in critically ill children. Study findings will be used to inform the design of a multicenter phase III trial evaluating the clinical and economic benefits to rapid normalization. Recruitment for this trial was initiated in January 2016 and is expected to continue until November 30, 2017. TRIAL REGISTRATION: Clinicaltrials.gov NCT02452762.

Vitamin D intervention in preschoolers with viral-induced asthma (DIVA): a pilot randomised controlled trial.

BACKGROUND: Trials in school-aged children suggest vitamin D supplementation reduces asthma exacerbations. Primary aim: to examine whether vitamin D3 (100,000 IU) rapidly raises serum 25-hydroxyvitamin D (25OHD) ≥75 nmol/L in asthmatic preschoolers. METHODS: In a double-blind, randomised, placebo-controlled trial, preschool-aged children with asthma received 100,000 IU vitamin D3 (intervention) or placebo (control), followed by 400 IU vitamin D3 daily for 6 months. Serum 25OHD was measured at baseline, 10 days, 3 and 6 months. Outcomes included the group difference in 25OHD change from baseline at 3 months (Δ25OHD); the proportion of children with 25OHD ≥75 nmol/L at 3 months; the pattern in serum vitamin D over 6 months; the proportion of children with hypercalciuria at any time point (safety); and group rates for oral corticosteroids. Continuous outcomes were analysed using generalised linear mixed models and group rate ratios of events per child were assessed using a Poisson distribution model. RESULTS: Twenty-two children were randomised (intervention:11; control:11) during winter. At 3 months, the group difference in Δ25OHD (7.2 nmol/L; 95 % CI: -13.7, 28.1) was not significant; yet, 100 % versus 54.5 % (intervention versus control) had serum 25OHD ≥75 nmol/L. There was a significant group difference in Δ25OHD at 10 days (110.3 nmol/L; 95 % CI: 64.0, 156.6). One child in each group had transient hypercalciuria at 10 days. Group oral corticosteroids rates were 0.82 and 1.18/child, intervention versus control (rate ratio = 0.68; 95 % CI: 0.30, 1.62; non-significant). CONCLUSIONS: Following 100,000 IU vitamin D3, all children reached serum 25OHD ≥75 nmol/L, compared with half who received placebo. Daily supplementation, sun exposure and insufficient power may explain the absence of a significant 3-month group difference in Δ25OHD. No clinically important alterations in bone metabolism biomarkers occurred. Group oral corticosteroid rates will inform sample size calculations for the larger trial. ( NCT01999907 , 25 November 2013).

Parathyroid hormone-ionized calcium dynamics over the first year of life.

BACKGROUND: Ionized calcium (iCa) is believed to be the principle determinant of parathyroid hormone concentration (PTH). However, previous studies contained few infants. METHODS: This ancillary study from our vitamin D3 dose-response trial in healthy, breastfed infants measured calcium, phosphorus, PTH and 25(OH)D (25-hydroxyvitamin D) at 1, 2, 3, 6, 9 and 12 months of age. The relationship between iCa and PTH was assessed by Pearson correlation and a mixed effects regression model to account for repeated measures. RESULTS: No significant correlations were observed between iCa and PTH at individual visits (p>0.2). After accounting for repeated measures, PTH decreased with increasing iCa (slope -5.25; 95% confidence intervals (CI) -8.78 to -1.73), decreased with increasing 25(OH)D (slope -0.006; 95% CI -0.009 to -0.002, and increased with later visits (6-12 months, p<0.001), CONCLUSIONS: We observed a weak negative relationship between iCa and PTH and an increase with age consistent with physiologic maturation.

Impact of Vitamin D Supplementation on Gross Motor Development of Healthy Term Infants: A Randomized Dose-Response Trial.

UNLABELLED: In addition to benefits for bone health, vitamin D is implicated in muscle function in children and adults. AIMS: To determine if vitamin D dosage positively correlated with gross motor development at 3 and 6 months of age. We hypothesized that higher doses would be associated with higher scores for gross motor skills. METHODS: A consecutive sample of 55 healthy, term, and breastfed infants from Montreal, Canada were recruited from a randomized trial of vitamin D supplementation between 2009 and 2012. Infants were randomized to 400 International Units (IU) (n = 19), 800 IU (n = 18) or 1,200 IU (n = 18) vitamin D3/day. Motor performance at 3 and 6 months was quantified by the Alberta Infant Motor Scale (AIMS). Plasma vitamin D3 metabolites were measured by tandem mass spectrometry. RESULTS: AIMS scores did not differ at 3 months. However, total AIMS scores and sitting subscores were significantly higher at 6 months in infants receiving 400 IU/day compared to 800 IU/day and 1,200 IU/day groups (p < .05). There were weak negative correlations with length and C-3 epimer of 25(OH)D. CONCLUSIONS: In contrast to our hypothesis, gross motor achievements were significantly higher in infants receiving 400 IU/day vitamin D. Our findings also support longer infants being slightly delayed.

Methodological issues in assessing plasma 25-hydroxyvitamin D concentration in newborn infants.

BACKGROUND: Although no gold standard exists, liquid chromatography tandem mass spectrometry (LC-MS/MS) is a precise and accurate method for the analysis of plasma 25-hydroxyvitamin D (25(OH)D). Immunoassays are more readily available and require small volume sampling, ideal for infant testing. The objective was to compare two commercially available immunoassays for measuring circulating 25(OH)D concentration in infant plasma against LC-MS/MS. METHODS: Capillary blood samples from 103 infants were analyzed for plasma 25(OH)D using an enzyme immunoassay (EIA, Octeia, IDS Ltd.) and radioimmunoassay (RIA, DiaSorin). Plasma 25(OH)D(3), C-3 epimer of 25(OH)D(3) (3-epi-25(OH)D(3)) and 24,25-dihydroxyvitamin D (24,25(OH)(2)D(3)) were measured on the same samples using LC-MS/MS. To establish whether plasma 24,25(OH)(2)D(3) or 3-epi-25(OH)D(3) interferes with these immunoassay results, the zero 25(OH)D calibrator from each assay kit was spiked with increasing amounts of 24,25(OH)(2)D(3) or 3-epi-25(OH)D(3). RESULTS: Classifying infants below the common vitamin D status targets of 50 nmol/L and 75 nmol/L respectively, 58% and 99% fell below using the RIA, 19% and 56% with the EIA and 31% and 76% with LC-MS/MS. Compared to LC-MS/MS, both immunoassays showed poor Bland-Altman limits of agreement for 25(OH)D concentrations (RIA: limits of agreement -27 to +13%; EIA: -12 to +41%), and mountain plots (folded cumulative distribution) depicted significant skew and bias. Spiked 24,25(OH)2D3 concentrations, but not 3-epi-25(OH)D3, appeared as >100% of known values on the EIA but not on the RIA thus, suggesting that the EIA may cross-react with 24,25(OH)(2)D(3) to a greater extent than 3-epi-25(OH)D(3). CONCLUSION: Two common immunoassays resulted in very different classifications of vitamin D status possibly related to the interference of other vitamin D metabolites. Based on these data, LC-MS/MS assessment of vitamin D status is recommended in young infants (4-6 weeks of age).

Effect of different dosages of oral vitamin D supplementation on vitamin D status in healthy, breastfed infants: a randomized trial.

IMPORTANCE: Vitamin D supplementation in infancy is required to support healthy bone mineral accretion. A supplement of 400 IU of vitamin D per day is thought to support plasma 25-hydroxyvitamin D (25[OH]D) concentrations between 40 and 50 nmol/L; some advocate 75 to 150 nmol/L for bone health. OBJECTIVE: To investigate the efficacy of different dosages of vitamin D in supporting 25(OH)D concentrations in infants. DESIGN, SETTING, AND PARTICIPANTS: Double-blind randomized clinical trial conducted among 132 one-month-old healthy, term, breastfed infants from Montréal, Québec, Canada, between March 2007 and August 2010. Infants were followed up for 11 months ending August 2011 (74% completed study). INTERVENTION: Participants were randomly assigned to receive oral cholecalciferol (vitamin D3) supplements of 400 IU/d (n=39), 800 IU/d (n=39), 1200 IU/d (n=38), or 1600 IU/d (n=16). MAIN OUTCOMES AND MEASURES: The primary outcome was a plasma 25(OH)D concentration of 75 nmol/L or greater in 97.5% of infants at 3 months. Secondary outcomes included 25(OH)D concentrations of 75 nmol/L or greater in 97.5% of infants at 6, 9, and 12 months; 25(OH)D concentrations of 50 nmol/L or greater across all times; growth; and whole body and regional bone mineral content. Data were analyzed by intention to treat using available data, logistic regression, and mixed-model analysis of variance. RESULTS: By 3 months, 55% (95% CI, 38%-72%) of infants in the 400-IU/d group achieved a 25(OH)D concentration of 75 nmol/L or greater vs 81%(95% CI, 65%-91%) in the 800-IU/d group, 92% (95% CI, 77%-98%) in the 1200-IU/d group, and 100% in the 1600-IU/d group. This concentration was not sustained in 97.5% of infants at 12 months in any of the groups. The 1600-IU/d dosage was discontinued prematurely because of elevated plasma 25(OH)D concentrations. All dosages established 25(OH)D concentrations of 50 nmol/L or greater in 97% (95% CI, 94%-100%) of infants at 3 months and sustained this in 98% (95% CI, 94%-100%) to 12 months. Growth and bone mineral content did not differ by dosage. CONCLUSIONS AND RELEVANCE: Among healthy, term, breastfed infants, only a vitamin D supplement dosage of 1600 IU/d (but not dosages of 400, 800, or 1200 IU/d) increased plasma 25(OH)D concentration to 75 nmol/L or greater in 97.5% of infants at 3 months. However, this dosage increased 25(OH)D concentrations to levels that have been associated with hypercalcemia. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00381914.

Molecular cloning of haemoglobin-binding protein HgbA in the outer membrane of Actinobacillus pleuropneumoniae.

From the porcine pathogen Actinobacillus pleuropneumoniae cultivated in iron-deficient or haem-deficient media, haemoglobin (Hb)-agarose affinity purification was exploited to isolate an outer-membrane protein of approximately 105 kDa, designated HgbA. Internal peptide sequences of purified HgbA were used to design oligonucleotide primers for PCR amplification, yielding amplicons that showed partial sequences with homology to hgbA of Pasteurella multocida. Upon screening two genomic libraries of A. pleuropneumoniae serotype 1 strain 4074, positive clones were assembled into an ORF of 2838 bp. HgbA (946 aa) includes a signal peptide of 23 aa and the deduced HgbA sequence (104 890 Da) also demonstrated a possible Ton box. The promoter region of hgbA from A. pleuropneumoniae serotype 1 showed consensus for -35 and -10 sequences and a putative Fur-binding site. RT-PCR confirmed that hgbA of A. pleuropneumoniae is upregulated in response to diminished levels of iron in the culture medium. While an internally deleted hgbA mutant was unable to use pig Hb as sole source of iron for growth, flow cytometry confirmed its Hb binding; the internally deleted sequences may not be required for Hb binding, but appear necessary for the iron supply from Hb. HgbA is required for growth of A. pleuropneumoniae in the presence of Hb as sole iron source.

Isolation of Campylobacter fetus subsp. fetus from a patient with cellulitis.

Campylobacter fetus subsp. fetus is a gram-negative, slender, spirally curved bacterial pathogen. It has been isolated from human blood, spinal fluid, and abscesses, but cellulitis associated with bacteremia is rare. We report its isolation from a blood culture of a human patient with cellulitis as well as difficulties encountered in determining the identity of the subspecies of C. fetus.