Measurements of bone turnover markers in premature infants

We determined the levels of circulating bone turnover markers in preterm in fants during the first weeks of life. Twenty premature infants (mean gestat ional age 27 +/- 2.2 weeks, mean birth weight 894 +/- 231 g) hospitalized i n the neonatal intensive care unit (NICU) at the Meir General Hospital, Isr ael, participated in the study. Measurements of bone turnover markers were performed at birth, and every week thereafter for an average follow-up of 1 1.2 +/- 0.7 weeks. Bone osteoblastic activity was assessed by measurements of circulating osteocalcin, bone-specific alkaline phosphatase (BSAP) and t he C-terminal procollagen peptide (PICP) levels. Bone resorption was assess ed by measurements of serum levels of the carboxy-terminal cross-links telo peptide of type I collagen (ICTP), All three markers of osteoblastic activi ty increased markedly and significantly during the first three weeks of lif e, and then continued to increase gradually until week 10 (p < 0.01), Circu lating ICTP levels increased in the first week of life and then decreased g radually throughout the follow-up (p < 0.01), The study participants were d ivided into premature infants born at extremely low birth weight (ELBW: <10 00 g, n = 12) and very low birth weight (VLBW: 1000-1250 g, n = 8), Osteoca lcin (in weeks 2-5 of life), PICP (weeks 3-5), and ICTP levels (weeks 2-3) were significantly higher in VLBW preterms, These results suggest increased bone formation in premature infants in the first three months of life, The increased bone turnover in VLBW compared to ELBW premature infants may be the result of a generally higher morbidity in ELBW preterm infants in early stages of life.