Vitamin D and parathormone levels of late-preterm formula fed infants during the first year of life

Mineral and nutritional requirements of preterm infant

Preterm infants are at risk of growth failure and metabolic bone disease due to insufficient nutrient supply in postnatal life. An ample provision of protein, energy, calcium and phosphates through parenteral or/and enteral nutrition is crucial for bone growth and mineralization. Additional vitamin D supplementation improves bone mineralization and enhance intestinal absorption of minerals.

Feeding the Late and Moderately Preterm Infant: A Position Paper of the European Society for Paediatric Gastroenterology, Hepatology and Nutrition Committee on Nutrition

Nutritional guidelines and requirements for late or moderately preterm (LMPT) infants are notably absent, although they represent the largest population of preterm infants. The European Society for Paediatric Gastroenterology, Hepatology and Nutrition (ESPGHAN) Committee on Nutrition (CoN) performed a review of the literature with the aim to provide guidance on how to feed infants born LMPT, and identify gaps in the literature and research priorities.Only limited data from controlled trials are available. Late preterm infants have unique, often unrecognized, vulnerabilities that predispose them to high rates of nutritionally related morbidity and hospital readmissions. They frequently have feeding difficulties that delay hospital discharge, and poorer rates of breastfeeding initiation and duration compared with term infants. This review also identified that moderately preterm infants frequently exhibit postnatal growth restriction.The ESPGHAN CoN strongly endorses breast milk as the preferred method of feeding LMPT infants and also emphasizes that mothers of LMPT infants should receive qualified, extended lactation support, and frequent follow-up. Individualized feeding plans should be promoted. Hospital discharge should be delayed until LMPT infants have a safe discharge plan that takes into account local situation and resources.In the LMPT population, the need for active nutritional support increases with lower gestational ages. There may be a role for enhanced nutritional support including the use of human milk fortifier, enriched formula, parenteral nutrition, and/or additional supplements, depending on factors, such as gestational age, birth weight, and significant comorbidities. Further research is needed to assess the benefits (improved nutrient intakes) versus risks (interruption of breast-feeding) of providing nutrient-enrichment to the LMPT infant.

Functional indicators of vitamin D adequacy for very low birth weight infants

OBJECTIVE

To identify the vitamin D status to optimize calcium and bone health in preterm infants.

STUDY DESIGN

Very low birth weight infants had measurement of 25-hydroxyvitamin D status and markers of calcium and bone health from birth to term age. Piecewise linear regression modeling was performed to identify a 25-hydroxyvitamin D threshold associated with stable parathyroid hormone concentration and bone mineralization.

RESULTS

In a cohort of 89 infants at term age, femur BMC and density increased linearly with 25-hydroxyvitamin D status until reaching a threshold of 48 ng/mL and 46 ng/mL, respectively. Parathyroid hormone status decreased as vitamin D status increased until reaching a plateau at 25-hydroxyvitamin D of 42 ng/mL.

CONCLUSION

Preterm infant vitamin D status was significantly associated with PTH status and femur mineralization with suggestion that achieving a specific 25-hydroxyvitamin concentration is associated with optimal calcium homeostasis and femur bone mineralization.

Randomized trial of two doses of vitamin D3 in preterm infants <32 weeks: Dose impact on achieving desired serum 25(OH)D3 in a NICU population

BACKGROUND

Recommendations for vitamin D supplementation for preterm infants span a wide range of doses. Response to vitamin D supplementation and impact on outcomes in preterm infants is not well understood.

OBJECTIVE

Evaluate serum 25(OH)D3 concentration changes after 4 weeks in response to two different doses of vitamin D3 supplementation in a population of premature infants and quantify the impact on NICU outcomes.

DESIGN

32 infants born at 24-32 weeks gestation were prospectively randomized to receive 400 or 800 IU/day vitamin D3 supplementation. Serum 25(OH)D3 levels were measured every 4 weeks. The Wilcoxon signed rank test was used to compare serum levels of 25(OH)D3 at 4 weeks and each subsequent time point. A p-value of <0.05 was considered statistically significant.

RESULTS

Serum 25(OH)D3 levels at birth were 41.9 and 42.9 nmol/l for infants in the 400 IU group and 800 IU group, respectively (p = 0.86). Cord 25(OH)D3 concentrations significantly correlated with gestational age (r = 0.40, p = 0.04). After 4 weeks of D3 supplementation, median 25(OH)D3 levels increased in both groups (84.6vs. 105.3 nmol/l for 400 vs. 800 IU/day respectively, with significantly more improvement in the higher dose (p = 0.048). Infants in the 400 IU group were significantly more likely to have dual energy x-ray absorptiometry (DEXA) bone density measurements <10 percentile (56% vs 16%, p = 0.04).

CONCLUSIONS

Improvement in 25(OH)D3 levels at 4 weeks, bone density, and trends towards improvement in linear growth support consideration of a daily dose of 800 IU of vitamin D for infants <32 weeks cared for in the NICU.

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.

A randomized double-blind controlled trial comparing two regimens of vitamin D supplementation in preterm neonates

OBJECTIVE

To compare the efficacy of 400 vs 1000 IU oral vitamin D supplementation in preterm neonates of 27 to 34 weeks gestation.

METHODS

This double-blind randomized controlled trial allocated preterm babies to receive either 400 or 1000 IU of vitamin D3 (n=60 in each group). Primary outcome was prevalence of vitamin D insufficiency (serum vitamin D levels<20 ng ml(-1)) at 40 weeks of corrected gestational age (CGA).

RESULTS

At term CGA vitamin D insufficiency was significantly lower in the 1000 IU group than in the 400 IU group (2% vs 64.6%, P⩽0.001). Although elevated vitamin D levels were seen in 9.8% of babies on 1000 IU per day, this was not associated with clinical or biochemical evidence of toxicity.

CONCLUSION

Supplementing preterm babies with 1000 IU of vitamin D3 daily decreases the prevalence of vitamin D insufficiency at term CGA. Excess levels of vitamin D may occur at this dose in some babies.

Persistent elevation of fibroblast growth factor 23 concentrations in healthy appropriate-for-gestational-age preterm infants

OBJECTIVE

To explore the temporal evolution of 25-hydroxyvitamin D [25(OH)D], its epimer, parathyroid hormone (PTH), fibroblast growth factor 23 (FGF23), and minerals in healthy appropriate-for-gestational-age preterms.

PATIENTS

A prospective study was undertaken in infants born at 28-32 weeks with monitoring at 1, 3, 5 weeks and term.

METHODS

Morning plasma and urine calcium; phosphorus; creatinine; PTH, C-terminal and intact FGF23 (iFGF23) and liquid chromatography-tandem mass spectrometry measurements of 25(OH)D were undertaken. Analyses included regression models.

RESULTS

Some 11 infants (5 males) were recruited at a median gestational age of 31.2 weeks (interquartile range: 28.1-31.8). Standard chemistries were normal. No infant was vitamin D deficient; 58% achieved 50 nmol/L with a median intake of 540 IU/day. High concentrations of C-3 epimer were detected. iFGF23 and C-terminal concentrations were persistently elevated (double and ten times adult norms, respectively). Tubular resorption of phosphorus was normal (88%±8%).

CONCLUSIONS

Most infants achieved acceptable 25(OH)D3 concentrations. The biologic significance of the elevated FGF23 is unclear.

Vitamin D in childhood and adolescence: an expert position statement

Vitamin D is a key hormone in the regulation of calcium and phosphorus metabolism and plays a pivotal role in bone health, particularly during pediatric age when nutritional rickets and impaired bone mass acquisition may occur. Great interest has been placed in recent years on vitamin D's extraskeletal actions. However, while recent data suggest a possible role of vitamin D in the pathogenesis of several pathological conditions, including infectious and autoimmune diseases, the actual impact of vitamin D status on the global health of children and adolescents, other than bone, remains a subject of debate. In the meantime, pediatricians still need to evaluate the determinants of vitamin D status and consider vitamin D supplementation in children and adolescents at risk of deficiency. This review is the result of an expert meeting that was held during the congress "Update on vitamin D and bone disease in childhood" convened in Pisa, Italy, in May 2013.

CONCLUSION

The collaboration of the international group of experts produced this "state of the art" review on vitamin D in childhood and adolescence. After dealing with vitamin D status and its determinants, the review outlines the current debate on vitamin D's health benefits, concluding with a practical approach to vitamin D supplementation during childhood and adolescence.

WHAT IS KNOWN

• Vitamin D deficiency is a worldwide health problem. • Vitamin D deficiency affects not only musculoskeletal health but also a potentially wide range of acute and chronic diseases. What is New: • We reviewed the literature focusing on randomized controlled trials of vitamin D supplementation during childhood and adolescence. • This review will help pediatricians to appreciate the clinical relevance of an adequate vitamin D status and it will provide a practical approach to vitamin D supplementation.

Vitamin D status and adequacy of standard supplementation in preterm neonates from South India

OBJECTIVE

The aim of this study was to assess vitamin D status of preterm babies at birth and adequacy of daily supplementation with vitamin D.

METHODS

This prospective cohort study recruited 111 preterm babies, 25 to 32 weeks' gestation from a tertiary care perinatal center in south India. Cord blood was assayed for serum calcium, phosphate, alkaline phosphatase, and 25-hydroxyvitamin D (25(OH)D). All of the babies were fed unfortified breast-milk and supplemented daily with calcium, phosphate, and 400 IU of vitamin D. At 6 weeks serum calcium, phosphate, alkaline phosphatase, parathyroid hormone, and 25(OH)D levels were estimated.

RESULTS

Of 111 preterm babies recruited, a total of 90 (81%) of the preterm babies were followed up until 6 weeks. The median (interquartile range) vitamin D level in the preterm group was 34.7 (25.6-50.1) and 19.3 (13.9-27.1) ng/mL at birth and 6 weeks, respectively. Using a cutoff value of <20 ng/mL to determine vitamin D insufficiency (VDI), it was observed that 12.6% of the babies were vitamin D insufficient at birth. This increased to 52.2% at 6 weeks despite the recommended supplementation with vitamin D (P < 0.001).

CONCLUSIONS

The prevalence of VDI was not high at birth; however, a large proportion of preterm babies were vitamin D insufficient at 6 weeks despite being supplemented with vitamin D 400 IU/day. The recommended vitamin D supplementation of 400 IU appears to be inadequate to prevent VDI, and hence randomized controlled trials looking at higher doses of vitamin D supplementation are needed.