Purpose or Case Report: To assess the relationship between radiographic findings and biochemical markers, such as serum alkaline phosphatase (ALP), used for screening of metabolic bone disease (MBD) in preterm infants.
Methods & Materials: Preterm infants who underwent serial wrist radiographs and biochemical studies in our neonatal intensive care unit between January and November 2014 were studied. Retrospective review of biochemical studies and wrist radiographs was performed. Patients were subdivided into four groups according to MBD severity by the wrist radiographs for the first analysis and into two groups according to presence of MBD for the second analysis.
Results: Twenty-seven (61.3%) and 6 (13.6%) of 44 infants had very low and extremely low birth weight, respectively. The highest ALP after serial follow up (ALP-h) and before first wrist radiograph (ALP-hb) was measured on average at 6.6 and 5.5 weeks, respectively, after birth. The ALP during the first wrist radiograph (ALP-s), ALP-h, and ALP-hb were significantly different between Grades 0 and 3 (p = 0.004). At second analysis, ALP-h, the ALP-hb, and serum phosphorous during the first radiograph (P-s) were significantly different between MBD presence and absence groups (p < 0.0125). Specificity of ALP-h/ALP-hb, with a cut-off value of 503.5 IU/L, in detecting radiographic change (76.9%) was higher than that of P-s (54.8%).
Conclusions: ALP-h/ALP-hb level in 5-6 week-old preterm neonates is a predictor of MBD. Further studies are required to distinguish normal neonates from neonates with mild MBD.