[Neonatal vitamin D status and calcium-phosphorus homeostasis in the third week of life].

Aim: Assessment of vitamin D status and calcium -phosphorus homeostasis in term newborns before routine supplementation.

Material And Method: Calcidiol (25OHD), calcium, phosphorus and alkaline phosphatase in serum and Ca (urine)/creatinine (urine) ratio (mg/mg), P (urine)/creatinine (urine) ratio (mg/mg) and tubular phosphate reabsorption rate (TRP= [1-(P(urine) / P(serum). creatinine serum/urine)].100%) in 3rd week of life in 56 appropriate for gestational age term neonates was measured. First group contains 35 newborns (62.5%) with normal 25OHD values and second group 21 newborns (37.5%) with hypovitaminosis D (25OHD < 11 ng/ml).

Result: Mean 25OHD concentration was 15.23 ng/ml + 8.57 ng/ml. Maternal vitamin D supplementation (10 ug/day) for more than 4 months of pregnancy was similar in both groups (55.9% vs. 52.4%) (p>0.05). There were 51.43% breastfed newborns in group one and 85.71% in group two (p=0.009). Median 25OHD concentration in breastfed newborns was 11.2 ng/ml and 18.5 ng/ml in formula fed babies (p=0.017). There were no statistical differences between groups in calcium (2.44 vs. 2.41 mmol/l), phosphorus (2.27 vs. 2.22 mmol/l) and alkaline phosphatase (261 vs. 266 U/L) blood concentration and Ca (urine)/creatinine (urine) ratio (0,34 vs. 0,25mg/mg) and TRP (86% vs. 88%) (p>0.05). The P (urine) /creatinine (urine) ratio in the first group was 2.3mg/mg and 1.42 mg/mg in the second group (p=0.048).

Conclusions: Neonatal vitamin D stores in the 3rd week of life are not more dependent on maternal vitamin D supplementation during pregnancy. Breastfed infants are at greater risk of hypovitaminosis D than formula fed infants, therefore earlier vitamin D supply should be considered. The hypovitaminosis D has no influence on basic parameters of Ca-P homeostasis in the 3rd week of life.