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A B C D E F G H I J K L M N O P Q

Test Identifier Information

 
Registration CodeCTEL
Method

Roche Cobas E411 Beta-Crosslaps

Diagnostic Use / Indications

The assay is specific for an octapeptide in the C-terminus of the α1 chain of type 1 collagen and accurately reflects osteoclast-mediated bone resorption. There is a significant diurnal variation (peak serum CTX between 2-6am) which is blunted after fasting. Samples should thus optimally be collected fasting in the early morning and specimen collection should be consistent during monitoring visits.
Clinical applications include
1. Assessing bone turnover (osteoporosis, hyperparathyroidism, Paget’s disease, thyrotoxicosis, immobility)
2. Evaluating the efficacy of anti-resorptive therapy - there is a mean 70% fall of β-CTX from baseline 3-6 months after initiating biphosphonate therapy and 50% after oestrogen replacement. Preliminary data suggests that a decline of >40% in β-CTX at 6 months has a 90-95% positive predictive value that a decline in bone density will be prevented on repeat DEXA scan 2 years later.
3. Prospective studies demonstrate that levels of bone resorption markers (including β-CTX) are associated with increased rate of bone loss and fracture risk independently of bone density. However, the translation of these findings into clinical practice requires further study.

See also C-telopeptide web page

External Price$33.68(Exclusive of GST)
  

Specimen Collection

 
Pre-Testing Requirements

Fasting preferred.

Specimen Collection Protocols

Collect blood between 0800 and 1000 hours. For repeat testing, sampling should be at the same time of day.

Patient Specimen0800-1000h, blood 2 mL EDTA (T53)
Paediatric Specimen0800-1000h, blood 0.6 mL EDTA (must get 0.3 mL plasma).
Sample Delivery to LabAmbient if no haemolysis, otherwise on ice/water slurry
  

Instructions for Referral to CHLabs

 
Aliquot Instructions>0.5 mL EDTA Plasma
Aliquot Transport to CHLAmbient overnight, but if hemolysis >1g/L Hb send on ice or frozen.
  

CHLabs Laboratory

 
DepartmentEndocrinology Laboratory
Contact Details Email Email
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Contact Phone Number(03) 364 0884 | x80884
Test AvailabilityWeekly
Turnaround Time1 - 6 days
Reference Interval

Female (ug/L):<2 yr: 0.43-1.70; 2-4 yr: 0.55-1.91; 5-6 yr: 0.47-1.97; >6-10 yr: 0.80-2.06; 11-14 yr: 0.50-2.75; 15-18 yr: <1.59;  Adult: <0.75.

Male (ug/L): <4 yr: 0.54-1.71; 5 yr: 0.68-1.80; 6-9 yr: 1.05-2.38; 10-15 yr: 1.00-2.90; >15-18 yr: 0.50-2.43;  Adult: <0.75.

Interpretation

Increased levels of β-CTx occur in osteoporosis, Paget’s disease, primary hyperparathyroidism, renal insufficiency and bone metastases.
Due to the diurnal rhythm of β-CTx it is recommended that samples be taken fasting in the morning (0800-1000am).

Uncertainty of Measurement

0.01 µg/L for < 0.1 µg/L; 13% for > 0.1 µg/L

Additional Information

C-telopeptide is more stable in EDTA plasma than in serum. In serum claimed stability is 6-8 hours (ambient to 4°C). The test manufacturers recommend a fasting sample but we find little difference between fasting and non-fasting. Fasting or non-fasting state, and time of day, should be consistent for repeated sampling of a patient.

Delphic Number Test Number6557

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