Osteoporosis-Bone Resorption Marker

hreynolds at uh.edu hreynolds at uh.edu
Fri Jun 14 13:14:35 EST 1996

The ACTIVE CrossLaps ELISA kit is designed for the specific quantitative 
measurement of C-telopeptide degradation products of type I collagen 
(CrossLaps) in urine, and is intended for in vitro diagnostic use as an 
indicator of human bone resorption.

Type I collagen comprises 90% of the organic matrix of bone and is 
synthesized primarily in bone.  During bone remodeling, type I collagen 
is degraded and the small peptide fragments are excreted in the urine.  
The high specificity of the ACTIVE CrossLaps ELISA for this degradation 
product of type I collagen makes the quantitative measurement of 
CrossLaps an excellent marker of bone resorption.

The ACTIVE CrossLaps ELISA is a 96-well kit featuring the convenience of 
a microtitre-plate format, a total assay incubation time of 2 hours and 
15 minutes, and sensitivity to 50 µg/L.  The standard range of this assay 
is 100 - 5000 µg/L of the CrossLaps antigen, and a single urine control 
is included with the kit.  Due to the biological variability observed 
with urine specimens collected at various time points, second morning 
void urine sampling is preferred.  Additionally, preservatives commonly 
used in urine specimens do not affect the performance of the CrossLaps 
ELISA.  This is an important consideration for assays of urine specimens 
since urine is typically collected in the presence of a preservative(s).
The assay is based on the competitive binding of the anti-CrossLaps 
antibodies to either soluble CrossLaps antigen or to CrossLaps 
antigen-coated microtitration wells.  Standards, controls and unknowns 
are added to the appropriate wells, then the anti-CrossLaps antibodies 
are added, and the wells are incubated for 1 hour.  The wells are washed 
and peroxidase conjugated anti-rabbit immunoglobulin is added.  The wells 
are then incubated again for 1 hour.  After a second washing step, the 
wells are incubated for 15 minutes with a chromogenic substrate (TMB), 
and the enzymatic  reaction is stopped by the addition of phosphoric 
acid.  The optical density of each of the wells is read at 450 nm.

The highly specific and sensitive CrossLaps ELISA is an effective tool 
for monitoring patient response to anti-resorptive therapies, and 
assessing bone resorption activity in patients with metabolic bone 
disease.  Bone remodeling is a dynamic process whereby bone is degraded 
and reformed on a continuous basis.  Healthy bone is a balance of these 
two processes.  Osteoporosis is a disorder characterized by an imbalance 
in bone remodeling in which the rate of bone resorption exceeds that of 
bone formation.

According to the National Osteoporosis Foundation (NOF), osteoporosis 
affects more than 25 million people in the United States, 80 percent of 
whom are women.  Forty percent of all women have at least one spinal 
fracture by the time they reach 80 years of age.  One third of all men 
will be affected by osteoporosis by age 75.  Overall costs associated 
with diagnosis and treatment of osteoporosis exceed $10 billion per year 
and will likely increase as the aging population continues to grow.  In 
addition to the use of hormone replacement therapies for postmenopausal 
osteoporosis patients, various pharmaceutical agents intended to inhibit 
bone resorption are currently in development or under investigation.  
Sensitive and responsive assays of exclusive biochemical markers of bone 
resorption and bone formation are the rational, cost-effective approach 
to monitoring patient response to such anti-resorptive therapies.

In addition to the ACTIVE CrossLaps ELISA kit, DSL offers a comprehensive 
panel of assays related to bone metabolism and calcium regulation.  The 
DSL Bone and Mineral Metabolism product line also features assays for 
human osteocalcin, intact-PTH, human calcitonin, salmon calcitonin, and 

DSL (Diagnostic Systems Laboratories, Inc.) has received FDA 510(k) 
clearance to market the DSL-10-1700, ACTIVE CrossLaps ELISA kit.

The DSL ACTIVE CrossLaps ELISA (catalogue number DSL-10-1700) is 
available in North America exclusively from DSL, Inc.  For more 
information regarding this assay and other DSL products, contact the DSL 
Customer Service Center in Webster, TX, USA by phone 800.231.7970 or 
713.332.9678, by fax 713.338.1895, or by e-mail mktg at dslabs.com

Diagnostic Systems Laboratories
445 Medical Center Blvd.
Webster, TX  77598

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