Sign in →

Test Code CTX C-Terminal Telopeptides, Plasma

Important Note

Patients on high does biotin (>5mg/day) should not have samples drawn until at least 8 hours after the last biotin administration.

Specimen Type

Preferred: Plasma

Acceptable: Serum

Container

Preferred: Lithium Heparin (Mint Green or Dark Green)

 

Acceptable: Serum Red Top tube or Gold SST

Preferred Volume

5 mL

Offsite Collection Instructions

1. It is recommended to draw blood as fasting (8 hours), morning samples.  For long-term investigations, the samples should always be taken under same conditions as the baseline sample, as the plasma concentration is to some extent subject to a circadian rhythm.

2. Serum should be centrifuged and aliquoted within 2 hours of collection.

3. Aliquoted samples should be refrigerated at 2-8°C prior and during transportation.

4. If above criteria are not met, specimen will be rejected.

 

UCMC Collection Instructions

1.It is recommended to draw blood as fasting (8 hours), morning samples.  For long-term investigations, the samples should always be taken under same conditions as the baseline sample, as the plasma concentration is to some extent subject to a circadian rhythm.

2. Samples need to be received in the lab within 2 hours of collection at room temperature.

3. Greater than 2 hours must be refrigerated at 2-8°C.

4. If the specimen cannot be sent to the lab within 4 hours of collection, it must be spun, aliquoted and refrigerated at 2-8°C.

5. All unspun specimens greater than 4 hours will be rejected.  

6. If above criteria are not met, specimen will be rejected.

Availability

24/7

Turnaround Time

4 hours

STAT Availability

Not Available

Test Usage

This test may be used as an aid in assessing bone resorption. The test may also be used as an aid in monitoring antiresorptive therapies (e.g. bisphosphonates, hormone replacement therapy – HRT) in postmenopausal women and individuals diagnosed with osteopenia.

Test Methodology

Electrochemiluminescence immunoassay (ECLIA)

Additional Information

The Elecsys ?-CrossLaps (CTx) assay is specific for crosslinked isomerized type I collagen fragments, independent of the nature of the crosslink.

CPT Code

82523

Minimum Volume

2 mL

Test Limitations

Results may be confounded by clinical conditions known to affect bone resorption, e.g. hyperparathyroidism or hyperthyroidism. Caution should be exercised when measuring plasma levels in patients with reduced renal function as this may lead to reduced excretion of plasma CTx and a consequent increase in the apparent plasma CTx levels is seen.  The Elecsys ?-CrossLaps/serum test 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.
For diagnostic purposes, the results should always be assessed in conjunction with the patient’s medical history, clinical examination and other findings. They should not be used as a sole determinant for executing or modifying an existing treatment regimen.

Critical Results

None

Coverage Information

CMS has established a national coverage policy (NCD) for Medicare for this test as of November 25, 2002. Please document medical necessity.

Reference Range

Men
30 – 50 years: 70 – 584 pg/mL
>50 – 70 years: 70 – 704 pg/mL
>70 years: 70 – 854 pg/mL

Women
Premenopausal: 70 – 573 pg/mL
Postmenopausal: 104-1008 pg/mL

Fee Code

43847

Test Includes

Quantitative determination of degradation products of type I collagen (c-terminal peptides – CTx) in plasma.