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Norms for Clinical Use of CXM, a Real-Time Marker of Height Velocity
Ryan F Coghlan1, Robert C Olney2, Bruce A Boston3
1Research Center, Shriners Hospitals for Children, Portland, Oregon.
Insights
Collagen X biomarker (CXM) in blood shows promise for real-time height velocity (HV) assessment in children. This study confirms CXM
Area of Science:
- Pediatric endocrinology
- Biomarker discovery
- Skeletal growth assessment
Background:
- Assessing height velocity (HV) is challenging due to slow growth rates.
- Current HV measurement methods (multi-month intervals) are inadequate for managing growth disorders.
- Preliminary findings suggest collagen X biomarker (CXM) in blood correlates with HV.
Purpose of the Study:
- To validate CXM as a reliable HV biomarker in a larger cohort.
- To establish working reference ranges for CXM in relation to age and sex.
- To assess CXM utility for tracking skeletal growth patterns.
Main Methods:
- CXM levels were measured in archived blood samples from 302 healthy children and 10 adults.
- Sex-specific reference ranges were calculated using 432 CXM measurements.
- Serial CXM values from 116 participants were plotted against observed HV.
- CXM stability was assessed across serum, plasma, and dried blood spot samples.
Main Results:
- A strong correlation between blood CXM and conventional HV was confirmed.
- CXM levels mirrored established HV norms across different ages, including the pubertal spurt.
- CXM demonstrated minimal variation across different sample types (serum, plasma, dried blood spots).
Conclusions:
- Blood CXM offers a potential method for real-time estimation of height velocity.
- Established sex-specific reference ranges facilitate skeletal growth assessment over time.
- CXM's stability in stored samples supports its use in retrospective studies.
Context:
Height velocity (HV) is difficult to assess because growth is very slow. The current practice of calculating it from measurements taken at several-month intervals is insufficient for managing children with growth disorders. We identified a bone growth by-product (collagen X biomarker, CXM) in blood that in preliminary analysis in healthy children correlated strongly with conventionally determined HV and displayed a pattern resembling published norms for HV vs age.
Objective:
The goal was to confirm our initial observations supporting the utility of CXM as an HV biomarker in a larger number of individuals and establish working reference ranges for future studies.
Design, Settings, And Participants:
CXM was assessed in archived blood samples from 302 healthy children and 10 healthy adults yielding 961 CXM measurements. A total of 432 measurements were plotted by age, and sex-specific reference ranges were calculated. Serial values from 116 participants were plotted against observed HV. Matched plasma, serum, and dried blood spot readings were compared.
Results:
A correlation of blood CXM with conventional HV was confirmed. Scatter plots of CXM vs age showed a similar pattern to current HV norms, and CXM levels demarcated the pubertal growth spurt both in girls and boys. CXM levels differed little in matched serum, plasma, and dried blood spot samples.
Conclusions:
Blood CXM offers a potential means to estimate HV in real time. Our results establish sex-specific, working reference ranges for assessing skeletal growth, especially over time. CXM stability in stored samples makes it well suited for retrospective studies.
