| CTXⅠ

Cross Linked C-Telopeptide Of Type I Collagen (CTXI) is a common bone turnover marker (BTM) that can be measured from plasma, serum, or urine. CTX-1 is released from intact type 1 collagen via cleavage of cathepsin K and can be detected by antibodies against the eight-amino acid sequence EKAHDGGR. Its levels show circadian changes that are altered by food intake, making the timing of sample collection an important consideration, which is usually done on an empty stomach. Studies have shown that increased levels of CTX-1 and bone-specific alkaline phosphatase (BSALP) are associated with an increased risk of fractures and osteoporosis.
 

| Typical data

As the OD values of the standard curve may vary according to the conditions of the actual assay performance (e.g. operator, pipetting technique, wash technique or temperature effects), the operator should establish a standard curve for each test. Typical standard curve and data are provided below for reference only.

 

Concentration (ng/mL)	10	5	2.5	1.25	0.62	0.31	0.15	0
OD	2.15	1.67	1.21	0.85	0.52	0.34	0.21	0.12
Corrected OD	2.03	1.57	1.02	0.73	0.4	0.22	0.13	-

 

| Repeatability

Intra-assay Precision (Precision within an assay)：CV% < 10%; Inter-assay Precision (Precision between assays)：CV% < 10%
 

| Recovery

The recovery of Rat CTXⅠ spiked at three different levels in samples throughout the range of the assay was evaluated in various matrices.

 

Sample Type	Range(%)	Average Recovery(%)
Serum(n=8)	84-101	96
Plasma(n=8)	92-105	102
Cell Culture Supernates(n=8)	96-108	105

 

| Linearity

Samples were spiked with high concentrations of Rat CTXⅠ and diluted with Universal Diluent to produce samples with values within the range of the assay.

 

		Serum(n=4)	Plasma(n=4)	Cell Culture Supernates(n=4)
1 : 2	Range (%)	84-95	88-96	90-110
	Average (%)	91	93	96
1 : 4	Range (%)	89-103	87-108	105-115
	Average (%)	94	98	108