Vitamin D and Metabolic Bone Parameters in Preterm Neonates

[Association of neonatal blood calcium levels with perinatal factors and neonatal urinary calcium levels measured by an intelligent urine test system]

OBJECTIVE

To study the association of neonatal blood calcium levels with perinatal factors and neonatal urinary calcium levels measured by an intelligent urine test system.

METHODS

The medical data of 96 full-term singleton neonates with mild diseases were collected by a cross-sectional survey, who were hospitalized in the Department of Neonatology, The First Affiliated Hospital of Xi'an Jiaotong University, from June to August 2018. Urinary calcium levels measured by an intelligent urine test system, total blood calcium levels, ionized calcium levels, and the mother's calcium and vitamin D supplementation during pregnancy were recorded.

RESULTS

Compared with the group without vitamin D supplementation for the mother (17 neonates), the group with vitamin D supplementation for the mother (79 neonates) had significantly higher levels of total blood calcium and ionized calcium (P < 0.05).The group with both vitamin D and calcium supplementation for the mother (68 neonates) had significantly higher levels of ionized calcium than controls (28 neonate) (P=0.05). There was no significant difference in the levels of total blood calcium and ionized calcium between the group with calcium supplementation for the mother (74 neonates) and the group without calcium supplementation for the mother (22 neonates) (P > 0.05). The hypothermia group (5 neonates) had a significantly lower level of total blood calcium than the normal body temperature group (91 neonates) (P < 0.05). There was a significantly positive correlation between the maternal blood total calcium level and the neonatal blood total calcium and ionized calcium levels (r=0.881 and 0.703 respectively; P < 0.05). The neonatal urinary calcium level measured by the intelligent urine test system was significantly correlated with the blood ionized calcium level (r=0.526, P=0.025).

CONCLUSIONS

Vitamin D supplementation during pregnancy can increase the blood levels of total calcium and ionized calcium in neonates, and calcium supplementation alone cannot increase the blood levels of total calcium or ionized calcium in neonates. Hypothermia in neonates might cause the reduction in blood calcium levels. The urinary calcium level measured by the intelligent urine test system is positively correlated with the blood level of ionized calcium.

Vitamin D status among preterm infants with cholestasis and metabolic bone disease

BACKGROUND

Metabolic bone disease of prematurity (MBD) is a common problem among preterm infants. Our previous study identified cholestasis as an important risk factor for the development of MBD. We conducted this study to determine the vitamin D status in preterm infants with MBD and cholestasis.

METHODS

We retrospectively reviewed medical record of preterm infants evaluated in NICU at Holtz Children's/Jackson Memorial Hospital between June 2014 and May 2016. Demographic, biochemical data, and vitamin D intake were collected and analyzed.

RESULTS

We identified 58 preterm infants (median gestational age 25 weeks) with MBD during this period. Twenty five infants also developed cholestasis. Median serum 25-hydroxyvitamin D level at the time of diagnosis of MBD was similar in cholestasis (C), (29.1 ng/ml, IQR 24.4-33.5), and non-cholestasis (NC), (28.7 ng/ml, IQR 22.7-34.6), group (p = 0.41). At the second measurement, average 6 weeks after the first measurement; median serum 25-hydroxyvitamin D level was lower (p = 0.02) in the C group (31.2 ng/ml, IQR 23.0-38.8) than in the NC group (36.5 ng/ml, IQR 28-45). However, the actual percentage of infants with vitamin D deficiency was similar in both the groups.

CONCLUSION

Most preterm infants with cholestasis and MBD had normal vitamin D status.