How is it used?
CTX is commonly used for diagnosing and monitoring patients with osteoporosis.
When is it ordered?
CTX is used in men and women who are at high risk for fractures – for instance those whose clinical history, bone mineral density (BMD), thyroid hormones, calcium and vitamin D tests suggest they may be at risk of osteoporosis.1 It is also used for people who are about to start taking medications for osteoporosis, who can use this test to help monitor the success of their therapy. 2
Because of the high inter-individual variability of bone turnover markers, the optimal strategy is to determine a baseline CTX value for the patient and then repeat testing in several months to observe the change in the patients bone-turnover status.
What does the test result mean?
Elevated levels of CTX indicate increased bone resorption. Increased levels are associated with osteoporosis, osteopenia, Paget disease, hyperthyroidism, and hyperparathyroidism.
In patients taking antiresorptive agents (bisphosphonates or hormone replacement therapy), a decrease of less or equal to 25% from baseline CTx levels (ie, prior to the start of therapy) 3 to 6 months after initiation of therapy indicates an adequate therapeutic response.
Is there a charge for the test?
This test is not covered by the provincial health insurance plans*, but it may be covered by extended health insurance plans. Contact LifeLabs to find out about the current fee for the test.
- Current Recommendations for Laboratory Testing and Use of Bone Turnover Markers in Management of Osteoporosis. Lee J et al, Ann Lab Med, 2012; 32(2): 105–112.
- Bone Turnover Markers In The Management Of Postmenopausal Osteoporosis. Brown JP et al, Clinical Biochemistry, 2009; 42:929-942.