CrossLaps
β-CrossLaps ( β-CTx ) are a bone marker for the detection of breakdown fragments of collagen . With a share of approx. 90%, collagen is the main component of the organic bone matrix . The area of application of the β-CrossLaps test is the diagnosis of osteoporosis .
Compared to the bone density measurement , which can only give an indication of the structural changes in the bone after about two years, CrossLaps offers the possibility of detecting changes in bone metabolism after three months. This makes it possible to use CrossLaps for therapy monitoring.
Diagnostic use of CrossLaps
The CrossLaps test is suitable for the following areas of application:
- Monitoring of anti-resorptive osteoporosis therapy ( bisphosphonates , hormone replacement therapy , SERM )
- Evidence of increased collagen breakdown
- Determination of fracture risk
The blood should always morning at the same time in an empty effected patients. The morning collection reduces the influence of the circadian rhythm on the results, since the maximum of the CrossLaps value is at night and the minimum in the afternoon. Furthermore, the intra-individual fluctuation of the results is greatly reduced by taking blood in the fasted state.
The CrossLaps reference ranges are laboratory dependent; The following values should be mentioned as examples:
| Woman man | Age | Reference range |
|---|---|---|
| woman | Pre- menopause | 25 to 573 pg / ml |
| menopause | 104 to 1008 pg / ml | |
| man | 30–50 years | 16 to 584 pg / ml |
| 51–70 years | up to 704 pg / ml | |
| over 70 years | up to 854 pg / ml |
CrossLaps for therapy monitoring
CrossLaps can be used to monitor anti-resorptive osteoporosis therapy.
Responder
If the therapy responds (the patient is a so-called responder ), the CrossLaps values drop after a few weeks and remain low with regular medication. Depending on the type of therapy, the values fall well below the 35% or 55% mark. The significant decrease in bone resorption markers in the 3–6 months after the start of antiresorptive therapy is associated with a significant decrease in the risk of fractures.
Non-responders
If the CrossLaps values do not show any significant change, the reasons could be the failure to take the medication or ineffectiveness of the therapy.
Osteoporosis Pathology and β-CrossLaps
The antibodies in the CrossLaps test detect so-called β-CrossLaps. These are a cleavage product (so-called linear degradation fragments) of the C-terminal Telo peptide (β-CTx) of type I collagen. The α- aspartic acid found in the C-terminal telopeptides is converted into β-aspartic acid (β-CTx) as the bone ages. Cross-linked fragments of the β-CTx contain twice the β-CTx antigen. These fragments, called β-CrossLaps, are released by bone resorption as a result of osteoclast activity. β-CrossLaps is therefore a specific breakdown product of bone collagen in the sense of a bone resorption marker.
credentials
- Christgau, S. et al. Clinical evaluation of the serum CrossLaps One Step ELISA, a new assay measuring the serum concentrations of bone derived degradation products of type 1 collagen C-telopeptides . In: ClinChem 1998; 44: 2290-2300
- Delmas, PD et al. Markers of bone turnover for monitoring treatment of osteoporosis with antiresorptive drugs . In: Osteoporos Int 2000; Suppl. 6: 66-76
- Eastell, R. et al. Relationship of early changes in bone resorption to the reduction in fracture risk with risedronate . In: J Bone Miner Res . 2003; 18: 1051-1056
- Garnero, P. et al. Evaluation of a fully automated serum assay for c-terminal cross-linking telopeptide of type I collagen in osteoporosis . In: ClinChem 2001; 47: 694-702
- Garnero, P. et al. Markers of bone turnover predict postmenopausal forearm bone loss over 4 years: the OFELY study . In: Journal of Bone and Mineral Research ; 1999; 14: 1614-1621
- Kraenzlin, Marius E .: Biochemical Markers of Bone Turnover and Osteoporosis Management . In: BoneKEy . 2007 July; 4 (7): 191-203, doi : 10.1138 / 20070266
- ↑ Leaflet: "Reference ranges ENDOC laboratory, as of December 10, 2010"
