Serum Levels Of C-terminal Telopeptide Research Articles

Serum levels of C-terminal telopeptide of type I collagen: a useful new marker of cortical bone loss in hemodialysis patients.

Renal osteodystrophy is a major complication in hemodialysis patients. Measurement of serum peptide derived from the degradation of bone collagen could potentially provide an indirect estimate of bone resorption. The present study estimated the significance of the C-terminal telopeptide of type I collagen (beta-CTx) as a serum bone resorption marker in male hemodialysis patients. The mean age and hemodialysis duration of the 160 patients were 59.7 years (26-86 years) and 67.2 months (17-142 months), respectively. Bone mineral density (BMD) in the distal third of the radius was measured using dual-energy X-ray absorptiometry twice with a 2-year interval. A blood sample was collected immediately before the hemodialysis session at the time of the second BMD measurement. Other serum bone markers determined were bone-specific alkaline phosphatase (BAP) and intact and N-terminal midfragment (N-Mid) osteocalcin (OC) as bone-formation markers and serum pyridinoline (PYD) and deoxypyridinoline (DPD) as bone resorption markers. Serum beta-CTx correlated significantly in a positive manner with serum PYD, DPD, BAP, intact OC, and N-Mid OC. Serum beta-CTx, as well as PYD, DPD, BAP, intact OC, and N-Mid OC, correlated significantly with BMD in the distal third of the radius at the second measurement and with the rate of BMD reduction during the preceding 2 years. The highest quartile of serum beta-CTx was positively associated with rapid bone loss, defined as a change in the value for BMD in the distal third of the radius falling within the upper tertile of patients, in 55% of cases, and each quartile progress in serum beta-CTx increased the odds ratio of rapid bone loss by a factor of 1.73. Since the Youden index was twice as accurate for beta-CTx, BAP and N-Mid OC as for intact PTH, these bone-remodeling markers may be better risk markers of cortical bone loss than intact PTH. Inclusion in the highest quartile of PTH (above 288 pg/ml) predicted rapid bone loss with a sensitivity of only 26%. This means that the upper limit for serum PTH level recommended by K/DOQI may be too high, since 74% of cases with rapid bone loss showed serum PTH levels of below 288 pg/ml. In conclusion, serum measurement of beta-CTx may provide a new commercially viable and relevant serum assay to reflect cortical bone resorption in hemodialysis patients.

Early degradation and serum appearance of type I collagen fragments after myocardial infarction

Although extracellular matrix-degrading enzymes matrix metalloproteinases (MMPs) are activated within minutes after myocardial infarction (MI), the time course of early MI-induced type I cardiac collagen degradation has not been assessed, nor has the ability of MMP inhibitor compounds, such as doxycycline (DOX), to limit these events. The objective of this study was to assess serum biomarker evidence of myocardial type I collagen degradation early (<48 h) after coronary occlusion (CO) and determine the capacity of DOX to ameliorate its release. CO studies were performed in untreated and DOX pre-treated pigs. Treated animals received DOX at 30 mg/kg/d. Radioimmunoassays were performed for serum levels of C-terminal telopeptide of collagen type I (ICTP) fragments. ICTP groups peaked by 6 h after MI. However, in DOX-treated animals, ICTP values returned to normal by 8 h. Average serum concentrations for ICTP values from 0 to 48 h post-MI were significantly inhibited by DOX treatment. In conclusion, serum biomarker results indicate that type I collagen degradation occurs within minutes after MI and that DOX likely reduces its degradation.

Biological activity of anastrozole in postmenopausal patients with advanced breast cancer: effects on estrogens and bone metabolism

BackgroundTo study the short-term biological effect of anastrozole on serum estrogens, androgens, 17-hydroxyprogesterone (17OH-PGR), gonadotrophins, sex hormone binding globulin (SHBG) and bone metabolism markers. Materials and methodsThirty-four consecutive patients with advanced breast cancer received anastrozole 1 mg/day. Blood samples were taken before commencement of treatment and at 2, 4, 8and 12 weeks during treatment to measure serum levels of estrogens (E1, E2 and E1-S), androgens [androstenedione (Δ4), dihydrotestosterone (DHT), testosterone (TST), free TST, dehydroepiandrosterone (DHEA) and dehydroepiandrosterone sulfate (DHEA-S)], 17OH-PGR, SHBG and gonadotrophins. As an indicator of bone resorption, we measured serum levels of C-terminal telopeptide of type I collagen (ICTP) and the cross-linked N-telopeptide of type I collagen (NTx), and for osteoblastic activity, intact osteocalcin (BGP) and bone alkaline phosphatase (BAP). ResultsAfter 2 weeks E1 and E1-S levels decreased on average by 56% (range 23.1–88.8%) and 75.8% (range 52.4–87.2%), respectively; E2 decreased on average by 62% (range 31.4–89.6%). No significant changes were detected in levels of androgens or 17OH-PGR. There was a significant increase in gonadotrophins over time (P = 0.0001 for both luteinizing hormone and follicle-stimulating hormone), and a significant decrease in SHBG (P = 0.0001). A progressive significant increase in bone metabolism serum markers was detected in all patients: BAP, P = 0.039; BGP, P = 0.016; ICTP, P = 0.0021; and NTx, P = 0.0013. In particular, patients with bone metastases had a statistically significant increase of bone resorption markers (ICTP, P = 0.0019; NTx, P = 0.025) and borderline for bone formation markers. In patients without bone disease, BAP, BGP and ICTP remained unchanged, whereas serum NTx significantly increased (P = 0.019). ConclusionsAnastrozole is a selective aromatase inhibitor as it does not modify serum levels of androgens and 17OH-PGR. In our experience no relationship was found in the short-term period between serum estrogen suppression and bone metabolism.