title: Measurement of urinary N-telopeptides and serum  C-telopeptides from type I collagen using a lateral  flow-based immunoassay.
abstract: Measuring bone turnover markers could detect early stages of osteoporosis and early responses to anti-osteoporotic treatments. Currently, commonly used bone turnover markers, N-telopeptides (NTx) and C-telopeptides (CTx), are measured using ELISA tests, which demands time and increases cost. Bone turnover markers need to be measured more easily for general use. Lateral flow-based immunoassay would be an appropriate method for this context. This study was performed to investigate the precision of a newly developed lateral flow-based immunoassay for measuring the urinary NTx and serum CTx, and their correlations with ELISA measurements. Urine NTx and serum CTx concentrations were determined by photoscan of newly developed strips, using a lateral flow-based immunoassay for 36 subjects (mean age 66.2 years, SD 7.5 years; four males and 32 females). Repeated measurement of urinary NTx and serum CTx were performed three times, using this technology for a precision test. The correlation of the lateral  flow-based immunoassay with the ELISA measurements was analyzed. Precision of the newly developed lateral flow based immunoassay was 0.974 (ICC, 95% confidence interval, 0.955 to 0.986) and 0.995 (ICC, 95% confidence interval, 0.991 to 0.997) for urinary NTx and serum CTx, respectively. The correlation of lateral flow based immunoassay with ELISA was 0.913 for urinary NTx and 0.872 for serum CTx. These results suggest that measuring the urinary NTx and serum CTx, using a lateral flow-based immunoassay, is a relevant method for point-of-care testing and screening of bone resorption markers.
authors.affiliation: Department of Orthopaedic Surgery, Seoul National University Bundang Hospital, Kyungki 463-707, Korea. oasis100@empal.com
authors.forename: Kyoung Min
authors.initials: KM
authors.lastname: Lee
authors.forename: Min Ho
authors.initials: MH
authors.lastname: Lee
authors.forename: Chin Youb
authors.initials: CY
authors.lastname: Chung
authors.forename: Woo Kyeong
authors.initials: WK
authors.lastname: Seong
authors.forename: Sang Dae
authors.initials: SD
authors.lastname: Lee
authors.forename: Moon Seok
authors.initials: MS
authors.lastname: Park
mesh_terms: D000368:Aged; D000818:Animals; D024042:Collagen Type I / Q000097:blood* / Q000652:urine*; D003710:Demography; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D006801:Humans; D007106:Immune Sera / Q000378:metabolism; D007118:Immunoassay / Q000379:methods*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D010455:Peptides / Q000097:blood* / Q000652:urine*; D012212:Rheology
chemical_list: D024042:Collagen Type I; D007106:Immune Sera; D010455:Peptides; C052929:collagen type I trimeric cross-linked peptide