medwireNews: A single measurement of plasma levels of a fragment of type X collagen (Collagen X bioMarker; CXM) may give an instant picture of how fast a child is growing, say researchers.
“We expect CXM to one day become a valuable tool for the estimation of growth velocity in the clinical setting”, say William Horton (Shriners Hospital for Children, Portland, Oregon, USA) and study co-authors.
They report that levels of CXM, which they explain is a by-product of endochondral ossification, “released into the circulation in proportion to overall growth plate activity”, correlated with growth velocity measured by conventional means in both girls and boys.
In a longitudinal analysis of 110 healthy children (54 girls, 56 boys) with a height z score ranging from –1.5 to 2.7, CXM correlated with height velocity at correlation coefficients of 0.83 for girls and 0.77 for boys.
“Considering that [height velocity] is the integrated product of hundreds of genetic and environmental factors, we believe identifying a marker whose level in girls and boys is 69%/59% explained by [height velocity]is remarkable”, write the researchers in The Journal of Clinical Endocrinology & Metabolism.
In a cross-sectional analysis of an additional 302 children (139 girls, 163 boys), with height z scores ranging from –3.5 to 3.4, CXM values again correlated with conventional growth data, identifying the pubertal growth spurt at the expected times in girls and boys.
A total of 199 children underwent Tanner staging. This revealed that CXM levels peaked at breast Tanner stage III in girls; in boys CXM levels were significantly higher at Tanner stages I–IV than at stage V.
“We predict the greatest potential clinical use of CXM will be to monitor changes in [height velocity] over time”, say Horton and team, particularly for monitoring disease progression or response to treatments.
They caution that “the value of single CXM measurements may be limited by the modest variability” in the correlation between CXM and height velocity, although they do anticipate this improving “as more samples are analyzed and sampling protocols become more rigorous”.
The team concludes: “If so, one-time CXM measurements may have potential as a real-time screening tool for children whose growth velocity is outside the normal range.”
By Eleanor McDermid
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