Evaluation of plasma carboxy-terminal cross-linking telopeptide of type I collagen concentration in horses.
OBJECTIVE
To evaluate a human assay for quantification of carboxy-terminal cross-linking telopeptide of type I collagen (CTX-I), assess the influence of age on plasma CTX-I concentration, investigate the relationship between plasma CTX-I and serum osteocalcin concentrations, and determine whether concentrations of plasma CTX-I or serum osteocalcin fluctuate in circadian manner in horses. HORSES: 75 clinically normal horses.


METHODS
Cross-reactivity between equine serum CTX-I and CTX-I antibodies in an automated electrochemiluminescent sandwich antibody assay (ECLIA) was evaluated via a specificity test (ie, dilution test) and recovery calculation. Serum osteocalcin concentration was measured with an equine-specific osteocalcin radioimmunoassay. To analyze diurnal variations in plasma CTX-I and serum osteocalcin concentrations, blood samples were obtained hourly during a 24-hour period.


RESULTS
Results of the dilution test indicated good correlation (r > 0.99) between expected serum CTX-I concentrations and measured serum CTX-I concentrations. The calculated CTX-I recovery was 97.6% to 109.9%. Plasma CTX-I and serum osteocalcin concentrations were correlated. Plasma CTX-I concentration was inversely correlated with age of the horse. No significant circadian variations in plasma CTX-I and serum osteocalcin concentrations were detected.


CONCLUSIONS
Results suggest that the fully automated CTX-I ECLIA can be used for evaluation of plasma and serum samples from horses and may be a useful tool to monitor bone metabolism changes. Horses in this study did not have notable diurnal fluctuations in serum osteocalcin and plasma CTX-I concentrations.
Carstanjen
Bianca
B
Department of Large Animal Internal Medicine, Faculty of Veterinary Medicine, University of Liège, Sart Tilman, Belgium.
Hoyle
Nicholas R
NR
Gabriel
Annick
A
Hars
Olaf
O
Sandersen
Charlotte
C
Amory
Hélène
H
Remy
Benoit
B
D000367:Age Factors; D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology*; D003094:Collagen / Q000097:blood*; D024042:Collagen Type I; D006736:Horses / Q000097:blood* / Q000502:physiology; D007163:Immunosorbent Techniques; D008163:Luminescent Measurements; D015675:Osteocalcin / Q000097:blood*; D010455:Peptides / Q000097:blood*; D011863:Radioimmunoassay
D024042:Collagen Type I; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide; D015675:Osteocalcin; D003094:Collagen