ARS | Publication request: Rickets and osteopenia are more common in infants <600g birth weight than those 600-1000g

Submitted to: Pediatric Academic Society
Publication Type: Abstract Only
Publication Acceptance Date: February 17, 2009
Publication Date: May 5, 2009
Citation: Mitchell, S.M., Rogers, S.P., Hicks, P.D., Hawthorne, K.M., Parker, B.R., Abrams, S.A. 2009. Rickets and osteopenia are more common in infants <600g birth weight than those 600-1000g [abstract]. Pediatric Academic Society. Abstract no. 5503.39.

Technical Abstract: Osteopenia and rickets are common among extremely low birth weight infants (ELBW, <1000g birth weight) despite current nutritional practices. To determine the incidence of osteopenia and rickets in ELBW infants. We evaluated all ELBW infants admitted to Texas Children's Hospital NICU in 2006 and 2007. Of 211 admissions, we excluded 98 patients admitted at >30 days of age or did not survive/stay for >6 weeks. Bone radiographs obtained in 32 infants were reviewed by a radiologist masked to laboratory values. In this cohort of 113 infants, peak alkaline phosphatase (P-APA) was found to have a significant inverse relationship with birth weight (BW), gestational age (GA) and serum phosphorus (Phos). Independent varible is BW, dependent variable is P-APA, variable r-value is -0.36 and p-value is <0.001. Independent variable is GA, dependent variable P-APA, variable r-value is -0.28 and p-value is 0.003. Independent variable is Phos, dependent variable P-APA, p-value is -0.28 and p-value is 0.003. In paired comparisons, infants with BW 800-1000g had significantly lower P-APA (615 +/- 252 IU/L, n=50) compared to infants 600-800g (808 +/- 323 IU/L, n=43) and infants <600g (957 +/- 346 IU/L, n=20), p<0.01. Thirty two patients had radiographic evaluation for rickets because of an elevated P-APA or clinical suspicion of rickets. Of these, 18 showed rickets and 14 showed osteopenia without rickets. Infants with BW <600g were more likely to have radiographic rickets (10/20 infants) compared to those with BW 600-800g (6/43 infants) and BW 800-1000g (2/50 infants), p<0.01 for each. P-APA was significantly higher in infants with rickets (1078 +/- 356 IU/L) compared to infants without rickets (686 +/- 281 IU/L), p<0.001. Mean Phos was lower in infants with rickets compared to infants without rickets (5.0 +/- 0.9 vs. 5.6 +/- 0.9, p=0.02). Neither diagnosis of bronchopulmonary dysplasia nor cholestasis was related to the presence of rickets. Among ELBW infants, BW was significantly inversely related to both P-APA and rickets. Radiographic evidence of rickets was common among ELBW infants, including 50% of infants <600g. Elevated P-APA and diagnosis of rickets were associated with decreased Phos, suggesting Phos deficiency. The very high risk of osteopenia and rickets among ELBW infants warrants consideration of earlier, more aggressive mineral supplementation.