β-CTX
(Biochemistry)
Investigation : β-CTX
Specimen type : Plasma
Spec container : EDTA 
Volume required : 4 ml
Reference range : See Below μg/l
Turnaround : <72 hours
Reference Intervals can be found here.

Clinical Use: β-CTX reflects resorption of mature collagen by osteoclasts. Any process increasing osteoclast activity results in an increase in β-CTX. Highest values 3-4 times the upper limit of normal are observed in immobilisation, metastatic cancer and in some patients with Pagetís disease. Values twice the upper limit of normal are often seen in Pagetís disease, osteoporosis, primary hyperparathyroidism, thyrotoxicosis and osteomalacia.

Patient preparation: Fasting morning sample (09:00-12:00) preferred. A baseline pre-treatment measurement is required if assessing response to antiresorption therapy.

Sample requirements for external users: EDTA plasma. Store frozen at -20į prior to dispatch and send frozen. Mininum sample requirement - 0.5 ml of EDTA plasma. Haemolysed samples are unsuitable for analysis.

Interpretation:
Osteoporosis Treatment
β-CTX reposnse to potent bisphosphonate (3/12 post commencing treatment):
"The least significant change (LSC) was determined to be 36%, meaning that an individual should display a ≥ 36% decrease of plasma βCTx concentrations when receiving antiresorptive therapy to have a < 5 % chance (p < 0.05) of the decrease being the result of random variation in marker concentration."

No baseline B-CTx (3/12 post commencing treatment):
B-CTx should be <0.30 ug/L

Pre-menopausal Geometric Mean: 0.306 ug/L
Post-menopausal Geometric Mean: 0.424 ug/L


If poor response to therapy check compliance

Additional information on CTXand its clinical use can be found here: CTX.



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