摘要：

BACKGROUND: -1 () measurements in plasma may be useful for the early detection and prognosis of (). Data on analytical performance and normal intra- and interindividual biological variation are required in order to interpret the utility of in . The aim of this study was to establish the biological and analytical variation of plasma in volunteers.: 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. 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.: A significant correlation between 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 (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 values decreased by 11% after storage for more than 16 months (p=0.0002). A systematic circadian variation in plasma levels was not observed (p=0.17). No significant variation of plasma was found in relation to physical exercise (p=0.92 [global test]).: Levels of plasma 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 levels. Possible storage-dependent decreases in plasma levels warrant further investigation.

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