110 - Leveraging Existing Radiographic Evidence to Optimize Screening for Metabolic Bone Disease of Prematurity

Publication Number: 2105.110

Lyndsay D. Long, University of Hawaii, John A. Burns School of Medicine, Honolulu, HI, United States; Lynn M. Iwamoto, University of Hawaii, John A. Burns School of Medicine, Honolulu, HI, United States; Leo Wu, University of Hawaii, John A. Burns School of Medicine, Honolulu, HI, United States; Lauren K. Suzuki, Tufts University, Pearl City, HI, United States; Juyun Lee, University of Hawaii, John A. Burns School of Medicine, Honolulu, HI, United States; Emmanuel R.E.. Kling, Kapiolani Medical Center for Women and Children - - Honolulu, HI, Honolulu, HI, United States; Arlene Kiyohara, University of Hawaii, John A. Burns School of Medicine, Honolulu, HI, United States; Hana Trent, University of Hawaii, John A. Burns School of Medicine, Honolulu, HI, United States

Background: Alkaline phosphatase (ALP) is a biomarker for elevated bone turnover used in the NICU to diagnose metabolic bone disease of prematurity (MBDP) in very low birthweight (VLBW) and very preterm (VPT) neonates. With this condition, bone mineralization is reduced and ALP is elevated. However, there are no standard diagnostic criteria for MBDP. While wrist X-rays (XRs) are used to diagnose MBDP, other routinely obtained XRs may show evidence of demineralization earlier.

Objective: Evaluate the association between peak ALP values and findings of bone demineralization on XRs obtained during standard care in the local NICU population.

Design/Methods: All babies born ≤32 weeks gestational age (GA) or ≤1500 grams in the local NICU in 2022-2024 were included. Those who expired, were transferred out before 2 weeks of age, or had congenital anomalies known to impact bone mineralization were excluded. Data collected included demographics, MBDP diagnosis, peak ALP values, and radiographic evidence of bone demineralization. 3 groups were identified: 1) those with MBDP diagnosis (MBDP dx), 2) those with boney changes but no MBDP diagnosis (boney changes only), and 3) those with no diagnosis and no boney changes (no findings). Continuous variables between groups were compared using one-way anova with Tukey post-hoc analysis, p < 0.05 considered significant. The retrospective analysis received IRB exempt status.

Results: Mean GA and BW differed significantly across the 3 groups. The MBDP dx group and the boney changes only group were younger and smaller at birth compared to those with no findings (Table 1). As expected, the infants with the MBDP dx had the highest mean peak ALP. The mean peak ALP in those with boney changes only was both significantly lower than that of the MBDP dx group and significantly higher compared to the no findings group. Screening using ALP started later in the MBDP dx and boney changes only group than in the no findings group. Notably, in both the MBDP dx group and the boney changes only group, the mean number of days to first XR evidence of demineralization was lower than the mean number of days to peak ALP.

Conclusion(s): This study shows an association between radiographic changes of demineralization seen on routine XRs with elevated ALP in VLBW and VPT infants. Previously, it was thought that evidence of bone demineralization on radiographs was a late finding in MBDP, but changes may appear on routine radiographs before the biochemical evidence. Screening for MBDP using ALP aids in evaluation, but attention to radiographic evidence of demineralization may lead to earlier recognition and treatment.

Table 1: Characteristics of Infants by Group
Definition of abbreviations: MBDP = Metabolic Bone Disease of Prematurity; Dx = diagnosis; GA = gestational age; BW = birthweight; ALP = alkaline phosphatase level; XR = X-ray
All values are Mean ± SD
ᐩ ALP not obtained for all infants in each group
*p < 0.05 vs Boney changes only
**p < 0.01 vs No findings