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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.

Purpose: To evaluate vitamin D status in mothers and their very low birth weight infants (VLBW) at birth (umbilical cord blood) and at discharge with currently recommended supplementation of vitamin D. Methods: Ninety-four infants with birth weight less than 1500 g completed the study. The total daily vitamin D intake was 800-1000 IU. We examined 25-hydroxyvitamin-D [25(OH)D] levels in maternal serum before labor, in cord blood, and in infants' serum at discharge. Results: Median (IQR) serum 25(OH)D was 21 (14-36) nmol/l [8 (6-15) ng/ml] in cord blood, and 46 (37-60) nmol/l [18 (15-24) ng/ml] at discharge. Serum 25(OH)D was <50 nmol/L in 71.3% of mothers, in 91.5% of cord blood samples, and in almost 60% of preterm newborns at discharge (after 8 weeks of supplementation). Serum 25(OH)D was <75 nmol/L in 88.3% of mothers, in 97.9% of cord blood samples, and in 91.4% of preterm newborns at discharge. Conclusions: In our cohort, we found that due to the very high prevalence of 25(OH)D deficiency among mothers, the current generally recommended dose of vitamin D (800-1000 IU per day) for VLBW infants was unable to improve vitamin D levels above the desired 50 or even 75 nmol/L before discharge.

Purpose: The aim of this pilot study was to estimate physiological parathyroid hormone (PTH) levels and their relationship with bone metabolism parameters in otherwise healthy preterm newborns with birth weight 1000-1500 g. Methods: PTH, 25(OH)D, S-Ca, S-P, and ALP were analysed from blood samples obtained from 20 preterm infants once a week up to the 36th gestational week. Results: Of the total 134 examined serum samples for PTH levels, the estimated range was 1.6-9.3 pmol/l (15.1-87.7 pg/ml). No statistically significant correlation of PTH level with that of S-Ca, S-P, or ALP was observed, except for the 56th day of life ( p  = .03; Rho = 0.76; n  = 8). From the second month of life, there was a statistically significant relationship only between PTH and 25(OH)D (Rho = -0.71, p ≤ .0001). In our cohort, vitamin D deficiency (20 ng/ml) occurred in 75% at birth and at 30% in the 36th gestational week. Conclusions: The physiological range indicated by the measurements was close to the reference limits for adults (1-7 pmol/l; 9.4-66 pg/ml). PTH level above this range can be considered as hyperparathyroidism in preterm neonates.