Severe vitamin D deficiency in preterm infants: possibly no association with clinical outcomes?

Abstract

Purpose

The primary objective of this study was to compare clinical outcomes of very low birth weight (VLBW) infants with 25-hydroxy vitamin D [25(OH)D] levels <25 nmol/l in umbilical cord blood versus VLBW infants with 25(OH)D levels in cord blood >25 nmol/l. The secondary objective was to evaluate umbilical cord vitamin D as a risk factor for respiratory distress syndrome (RDS) in preterm infants.

Methods

We examined 25(OH)D levels in umbilical cord blood and in infants’ serum at discharge from the neonatal intensive care unit. We evaluated the associations between severe vitamin D deficiency and various laboratory findings and clinical outcomes.

Results

Eighty one infants with birth weight less than 1500 g met the entry criteria for this study and were divided to groups according to umbilical cord blood vitamin D [Group A: 25(OH)D < 25 nmol/l; 10 ng/ml and Group B: 25(OH)D > 25 nmol/l; 10 ng/ml]. Overall, 81.5% of the infants had a 25(OH)D level <50 nmol/L and 44.4% had a level <25 nmol/L. The laboratory findings and the subsequent clinical outcomes were comparable in infants in both groups (non-significant difference). Only the infants in the 25(OH)D 25 nmol/L group had a lower calcium in urine at age 28 d (p=.0272). In addition, we found in this study that umbilical cord vitamin D level does not lead to a higher or lower risk of RDS (odds ratio 1.044; 95% confidence interval 0.349–0.88; p=.0771).

Conclusions

In our prospective cohort study, we found no significant association between vitamin D status and selected clinical outcomes when using a cut-off of 25 nmol/l (severe vitamin D deficiency) in preterm infants.

Keywords:

• Vitamin D
• 25-hydroxyvitamin D
• preterm infants
• prematurity
• clinical outcome

Acknowledgment

The authors are grateful to Ian McColl MD, PhD for assistance with the manuscript and to Vera Holkova for evaluations of lumbar spine densitometry.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Funding

This work was supported by University Hospital Hradec Kralove, Czech Republic project MH CZ – DRO, grant no. [UHHK, 00179906]. The study was supported by the Specific University Research Program, grant no. [SVV 260396] from Charles University, Faculty of Medicine in Hradec Kralove.