@article{fed0360b1b984b75aad23a370de6e045,
title = "Assessment of the biological variation of plasma tissue inhibitor of metalloproteinases-1",
abstract = "BACKGROUND: Tissue inhibitor of metalloproteinases-1 (TIMP-1) measurements in plasma may be useful for the early detection and prognosis of colorectal cancer (CRC). Data on analytical performance and normal intra- and interindividual biological variation are required in order to interpret the utility of TIMP-1 in CRC. The aim of this study was to establish the biological and analytical variation of plasma TIMP-1 in volunteers. MATERIAL AND METHODS: Three separate studies were undertaken. 1: Plasma was collected from 23 volunteers 6 times within a 3-week period, first in September 2004 (round [R] 1), then repeated in May 2005 (R2) and May 2006 (R3) in the same group of individuals. TIMP-1 levels were determined by the MAC15 ELISA assay and with the Abbott ARCHITECT i2000 Immunoanalyzer. 2: Circadian variation was evaluated in plasma collected 7 times within a 24-hour period (n=16). 3: Effects of physical exercise were evaluated in plasma collected before and after bicycling (n=14). In studies 2 and 3 TIMP-1 levels were determined with the MAC15 ELISA assay only. RESULTS: A significant correlation between TIMP-1 MAC15 and ARCHITECT i2000 was shown (rs=0.78, p<0.002), with consistently higher levels being detected by the ARCHITECT i2000. Median levels of TIMP-1 (ARCHITECT) at 8 a.m. in each round were 74.9 ng/mL (range 65.7-89.9) (R1), 87.3 ng/mL (range 72.7-127.9) (R2), and 81.9 ng/mL (range 66.8-113.6) (R3). The within-subject variation was 10.7%, the variation between rounds was 7.4%, and the intraclass correlation was 46.2%. Comparison between the 3 rounds and time of collection showed that TIMP-1 values decreased by 11% after storage for more than 16 months (p=0.0002). A systematic circadian variation in plasma TIMP-1 levels was not observed (p=0.17). No significant variation of plasma TIMP-1 was found in relation to physical exercise (p=0.92 [global test]). CONCLUSION: Levels of plasma TIMP-1 in volunteers show limited circadian, day-to-day, week-to-week and season-to-season variation. In addition, physical exercise has no impact on plasma TIMP-1 levels. Possible storage-dependent decreases in plasma TIMP-1 levels warrant further investigation.",
keywords = "Adult, Aged, Analysis of Variance, Blood Chemical Analysis, Circadian Rhythm, Colorectal Neoplasms, Enzyme-Linked Immunosorbent Assay, Exercise, Female, Humans, Immunoassay, Male, Middle Aged, Reference Values, Time Factors, Tissue Inhibitor of Metalloproteinase-1, Tumor Markers, Biological",
author = "Camilla Frederiksen and Lomholt, {A F} and T Lottenburger and Davis, {G J} and Dowell, {B L} and Blankenstein, {M A} and Christensen, {Ib Jarle} and N Brunner and Nielsen, {Hans J{\o}rgen}",
year = "2008",
language = "English",
volume = "23",
pages = "42--7",
journal = "International Journal of Biological Markers",
issn = "0393-6155",
publisher = "Wichtig Editore s.r.l",
number = "1",
}