Bone Turnover Markers in Premature Infants

Objective: We aimed to evaluate the bone turnover markers in preterm infants, and analyze their relationship with growth, urinary calcium (Ca) and phosphorus (P). Subjects and Method: Thirty-nine premature infants with enteral feeding started before the 5th day of life, and 20 full-term infants, as control group, were enrolled for the study. The weight and length of all premature infants were measured at birth and repeated at 4 weeks of age. Blood samples and urine were obtained for bone turnover markers at the second measurement. Results: Serum ß-CrossLaps and urinary deoxypyridinoline, calcium, tubular phosphate reabsorption (TPR) and TPR/GFR were significantly higher in preterm infants (P<0.05 for all parameters). There was significant correlation of osteocalcin with birth weight (r=0.306, P=0.05) and weight at 4 weeks (r=0.307, P=0.047); and negative correlation of urinary deoxypyridinoline with birth weight (r=-0.310, P=0.05), weight gain (r=0.625, P=0.001) and weight at 4 weeks (r=-0.387, P=0.015). Conclusion : A significant correlation was found between urinary deoxypyridinoline and TPR (r=0.314, P=0.05). Preterm infants with low birth weight and low weight gain risk getting osteopenia. Measurement of TPR and calcium excretion may be a good marker of preterm osteopenia.