Collagen Type I C-Telopeptide (CTx)

Test Code

CPT Codes

Preferred Specimen
1 mL serum

Patient Preparation
A minimum of 12 hours fasting is required. Fasting morning collection 8-10 am. (Diurnal variations cause elevated levels at night).

Dietary supplements containing biotin may interfere in assays and may skew results to be either falsely high or falsely low. For patients receiving the recommended daily doses of biotin, draw samples at least 8 hours following the last biotin supplementation. For patients on mega-doses of biotin supplements, draw samples at least 72 hours following the last biotin supplementation.

Minimum Volume
0.5 mL

Allow blood to clot (10-15 minutes) at room temperature. Centrifuge and separate the serum from the cells. Freeze as soon as possible.

Transport Container
Transport tube

Transport Temperature
Red-top tube (no gel) (preferred): Frozen
Serum separator tube: Refrigerated (cold packs)

Specimen Stability
Room temperature: 16 hours
Refrigerated: 72 hours
Frozen: 90 days

Reject Criteria (Eg, hemolysis? Lipemia? Thaw/Other?)
Moderate to gross hemolysis • Grossly lipemic • Grossly icteric

Immunoassay (IA)

Setup Schedule
Set up: Tues-Sat; Report available: 1-3 days

Reference Range
Adult Male
18-29 Years87-1200 pg/mL
30-39 Years70-780 pg/mL
40-49 Years60-700 pg/mL
50-68 Years87-345 pg/mL
Adult Female
18-29 Years60-640 pg/mL
30-39 Years60-650 pg/mL
40-49 Years50-465 pg/mL
>49 YearsNot established
Pediatric Male
5-9 Years574-1849 pg/mL
10-13 Years519-2415 pg/mL
14-17 Years435-2924 pg/mL
Pediatric Female
5-9 Years574-1849 pg/mL
10-13 Years519-2415 pg/mL
14-17 Years242-1291 pg/mL

Clinical Significance

CTx is useful to assess bone resorption in patients with metabolic bone disease. The test is also useful in monitoring therapy to slow or halt osteoporotic bone loss.

Performing Laboratory
Quest Diagnostics Nichols Institute
14225 Newbrook Drive
Chantilly, VA 20153

The CPT Codes provided in this document are based on AMA guidelines and are for informational purposes only. CPT coding is the sole responsibility of the billing party. Please direct any questions regarding coding to the payor being billed. Any Profile/panel component may be ordered separately. Reflex tests are performed at an additional charge.