Coupon Codes not valid for this testing. Fasting Required: Yes, 12 hours Lab: Quest Diagnostics Specimen: Blood Results: Test run Tues, Thurs, Sat; Report available in 3-5 days Average processing time Note: Result turnaround times are an estimate and are not guaranteed. Our reference lab may need additional time due to weather, holidays, confirmation/repeat testing, or equipment maintenance. Special Instructions: 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. Patient Instructions: Collection must be done between 8 am - 10 am. Description: 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. Alternative Name(s): C-Telopeptide, Serum, CTX, Beta-Crosslaps