Diurnal, weekly, and long-time variation in serum concentrations of YKL-40 in healthy subjects.
Serum YKL-40 is a potential biomarker of prognosis in cancer patients, but assessment of serum YKL-40 requires knowledge of its normal variation. In this study, we evaluated diurnal, weekly, and long-term variation in serum YKL-40 in healthy subjects using a commercial ELISA. The intra-assay coefficient of variation was <or=5.0% and interassay <or=10.2%. Systematic changes in diurnal measurements of serum YKL-40 could not be shown. Physical exercise for 20 min had no effect on serum YKL-40. The within-subject coefficient of variation, including variation over time and interassay, was 28.8% and 30.2% over a period of 2 and 3 years, and the intraclass correlation coefficients were 72.4% and 72.2%, indicating reasonable reliability of serum YKL-40 measurements. The 95% confidence limits for the difference between two measurements (same subject), including interassay variation, were a 52% reduction and a 109% increase in serum YKL-40. These studies show that relatively small variation is found in serum YKL-40 in healthy subjects. However, a single measurement of serum YKL-40 from an individual may not have a prognostic value, and serum YKL-40 alone cannot be a good biomarker for cancer because serum YKL-40 can be elevated in patients with other diseases characterized by inflammation and tissue remodeling.
Department of Rheumatology Q107, Herlev Hospital, Herlev Ringvej 75, DK-2730 Herlev, Denmark. julia.johansen@post3.tele.dk
Julia S
JS
Johansen
Tine
T
Lottenburger
Hans Jørgen
HJ
Nielsen
Jens Erik B
JE
Jensen
Mads N
MN
Svendsen
Gine
G
Kollerup
Ib J
IJ
Christensen
D054392:Adipokines; D000293:Adolescent; D000328:Adult; D000368:Aged; D014408:Biomarkers, Tumor / Q000097:blood*; D000071451:Chitinase-3-Like Protein 1; D002940:Circadian Rhythm; D004797:Enzyme-Linked Immunosorbent Assay; D015444:Exercise / Q000502:physiology; D005260:Female; D006023:Glycoproteins / Q000097:blood*; D006801:Humans; D037102:Lectins; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D009369:Neoplasms / Q000097:blood; D011379:Prognosis; D012016:Reference Values; D015203:Reproducibility of Results
D054392:Adipokines; D014408:Biomarkers, Tumor; C084533:CHI3L1 protein, human; D000071451:Chitinase-3-Like Protein 1; D006023:Glycoproteins; D037102:Lectins