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Urinary pyridinoline and deoxypyridinoline excretion in children
N J Shaw1, J Dutton, W D Fraser
1Institute of Child Health, Royal Liverpool Children's Hospital, Alder Hey, UK.
Insights
Urinary collagen breakdown markers, pyridinoline and deoxypyridinoline, are highly excreted in children. However, significant day-to-day variability limits their clinical utility in growing children.
Area of Science:
- Biochemistry
- Pediatric Endocrinology
- Biomarkers
Background:
- Limited data exist on urinary collagen breakdown markers in pediatric populations.
- Pyridinoline (Pyr) and deoxypyridinoline (DPyr) are key cross-linking amino acids in collagen metabolism.
Purpose of the Study:
- Determine normal ranges for urinary Pyr and DPyr in children.
- Assess variability of these markers in individual children.
- Examine the impact of growth hormone (GH) treatment on Pyr and DPyr excretion.
Main Methods:
- Cross-sectional study of 109 healthy children (2-15 years) and sequential samples from 4 children on GH treatment.
- High-performance liquid chromatography (HPLC) for Pyr and DPyr measurement.
- Excretion ratios calculated against urinary creatinine.
Main Results:
- High urinary Pyr and DPyr excretion observed across all pediatric age groups, with no age-related correlation.
- No correlation found between Pyr/DPyr and serum parathyroid hormone or urinary hydroxyproline.
- Significant day-to-day variability in excretion noted in individual children; a rise was observed in children on GH treatment.
Conclusions:
- Children exhibit higher urinary Pyr and DPyr excretion compared to adults.
- The substantial variability in single morning urine samples restricts the practical application of these collagen cross-link markers in pediatric monitoring.
Objective:
There are few data on urinary markers of collagen breakdown in children. We have determined a normal range for urinary pyridinoline and deoxypyridinoline in children, assessed the variability in excretion in individual children and examined the effect of GH treatment on the excretion of these collagen cross-links.
Design:
A cross-sectional study of a group of healthy children and sequential samples from children receiving GH treatment.
Patients:
One hundred and nine healthy children aged 2-15 years, 8 healthy children aged 4-11 years and 4 children receiving GH treatment.
Measurements:
Total pyridinoline and deoxypyridinoline excretion were measured by high performance liquid chromatography after initial acid hydrolysis and cellulose extraction steps. Serum parathyroid hormone was measured using a two-site immunoradiometric assay and urinary hydroxyproline by Ehrlich's reaction using a colorimetric assay. Pyridinoline and deoxypyridinoline excretion were expressed as a ratio against urine creatinine.
Results:
High excretion of pyridinoline (Pyr) and deoxypyridinoline (DPyr) was seen at all ages with no apparent relation to age (mean Pyr/Cr 115 nmol/mmol and DPyr/Cr 31 nmol/mmol). No correlation was found with serum parathyroid hormone or urinary hydroxyproline excretion. Marked day to day variation was seen in individual children. A progressive rise in excretion was seen in children receiving GH treatment with no significant correlation to height velocity.
Conclusions:
There is a high excretion of the pyridinium cross-linking amino acids in children of all ages compared to adults. However, a high variability exists in single morning urine samples which will limit the usefulness of these markers in growing children.