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Test Code CTX Isomerized C-Terminal Type I Collagen

Important Note

This test may be affected by biotin interference. Patients on high dose biotin (5mg/day or more) should not have samples drawn until at least 24 hours after the last biotin administration.

Specimen and Container/Tube

Specimen Type: Plasma

Preferred Specimen: Li-Heparin Mint Green Top

Other Acceptable specimens: Gold Top, Red Top, Lavendar K2 Top, Lavendar K3 Top

Specimen Handling and Transport Instructions

UCMC Onsite Instructions: 

  • Collect specimen per standard collection procedure and send to laboratory immediately. 

 

UCMC Offsite and UC MedLab Outreach Instructions: 

  • Samples should be centrifuged within 2 hours of collection.
  • Centrifuge specimens at >2500 x g for 10 minutes at room temperature.
  • Aliquot sample into plastic transport tube containing a minimum of 0.2 mL of specimen.
  • Samples must be sent frozen at -20oC.

Rejection Criteria

  • Common specimen rejected situations include: incorrect specimen type, insufficient volume, missing or incomplete specimen identifiers, incorrect specimen transport, or specimens outside stability limits. 
  • Specimens that are clotted or grossly hemolyzed.
  • Specimens that were transported unspun/whole blood and draw time is greater than 6 hours

Reference Values

Test

Age

Sex

Reference Range

CTX

All

Female

Premenopausal

70 - 573 pg/mL

CTX

All

Female

Postmenopausal

104 - 1008 pg/mL

CTX

30 - 50 years

Male

70 - 584 pg/mL

CTX

50 - 70 years

Male

70 - 704 pg/mL

Critical Values

Analyte

Unit

Low

High

Age

N/A

N/A

N/A

N/A

N/A

CPT Codes

82523

LOINC Codes

41171-0

Volume

Preferred Volume: 0.5 mL

Minimum Volume: 0.2 mL

Specimen Stability

Storage Temperature

Plasma Stability Li Heparin

Room Temperature

4 hours

Refrigerated

8 hours

Frozen

3 months

 

Storage Temperature

Plasma Stability K2 and K3 EDTA

Room Temperature

24 hours

Refrigerated

8 days

Frozen

3 months

 

Storage Temperature

Serum Stability

Room Temperature

6 hours

Refrigerated

8 hours

Frozen

3 months

Collection Instructions

Collect specimen per standard laboratory collection procedures. 

 

Test Components

CTX

Clinical Indications

Determination of the C terminal telopeptides in serum is recommeded for monitoring the efficacy of antiresorptive therapies (e.g. bisphosphonates or hormone replacement therapy - HRT) in postmenopausal women and individuals diagnoised with osteoporosis or other bone diseases. By this means, therapy induced changes can be demonstrated after just a few weeks.

Methodology

Electrochemiluminescence immunoassay (ECLIA) (Roche Diagnostics)

Additional Information

  • Results should always be assessed in conjunction with patient's medical history, clinical examination and other findings.
  • It is recommended to draw blood as fasting, morning samples. For long-term investigations, the samples should always be taken under same conditions as the baseline sample, as the serum β-CTx concentration is to some extent subject to a circadian rhythm.
  • By determining a bone resorption marker, the activity of bone turnover can be found. In physiologically or pathologically elevated bone resorption (e.g. in old age or as a result of osteoporosis), type I collagen is degraded to an increased extent, and there is a commensurate rise in the level of collagen fragments in blood.
  • Elevated serum concentrations of isomerized C-terminal telopeptides of type I collagen have been reported for patients with increased bone resorption. The serum levels return to normal during resorption-inhibiting therapy.
  • Results may be confounded by clinical conditions known to affect bone resorption, e.g. hyperparathyroidism or hyperthyroidism.
  • Caution should be exercised when measuring serum β-CTx levels in patients with reduced renal funtion as this may lead to reduced excretion of serum β-CTx and a consequent increase in the apparent serum β-CTx levels is seen.
  • The Elecsys β-CrossLaps/Serum assay is not suited to predict the development of an osteoporosis case or a fracture risk and should not be used with hyperparathyroidism or hyperthyroidism either.
  • Should not be used as a sole determinant for deciding on or modifying an existing treatment regimen.

Turnaround Time

Turnaround times are relative to the time the specimen is received in the test laboratory. 

 

STAT Turnaround Time: Not available as STAT test

Routine Turnaround Time: up to 4 hours

Testing Schedule:  24/7

Synonyms/Keyword Search

β-CrossLaps, BCTXM C-Telopeptide, isomerized C-terminal telopeptides, CTx

Last Review Date

8/19/2024