Risk factors for rickets of prematurity have not been re-examined since introduction of high mineral formula, particularly in ELBW infants. We analyzed the incidence and the risk factors of rickets in extremely low birth weight (ELBW) infants. As a retrospective case-control study from 2004 to 2008, risk factors were analyzed in 24 patients with rickets versus 31 patients without. The frequency of rickets in ELBW infants was 24/55 (44%). Infants with rickets were diagnosed at 48.2 +/- 16.1 days of age, and improved by 85.3 +/- 25.3 days. By radiologic evaluation, 29% were grade 1 rickets, 58% grade 2 and 13% grade 3. In univariate analysis, infants with rickets had significantly higher incidence of patent ductus arteriosus, parenteral nutrition associated cholestasis (PNAC), severe PNAC and moderate/severe bronchopulmonary dysplasia (BPD). In multiple regression analysis, after adjustment for gestation and birth weight, rickets significantly correlated with severe PNAC and with moderate/severe BPD. Serum peak alkaline phosphatase levels were significantly elevated in rickets (P < 0.001). In ELBW infants, the incidence of rickets of prematurity remains high and the incidence of severe PNAC and moderate/severe BPD was significantly increased 18 and 3 times, respectively.
Alkaline Phosphatase/blood ; Birth Weight ; Bronchopulmonary Dysplasia/*etiology ; Case-Control Studies ; Cholestasis/*etiology ; Female ; Gestational Age ; Humans ; Incidence ; Infant ; Infant, Extremely Low Birth Weight ; Infant, Newborn ; Infant, Premature ; Male ; Parenteral Nutrition/*adverse effects ; Regression Analysis ; Retrospective Studies ; Rickets/enzymology/*epidemiology/radiography ; Risk Factors ; Severity of Illness Index