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Intra‐individual short‐term variability of prostate‐specific antigen and other kallikrein markers in a serial collection of blood from men under evaluation for prostate cancer
Author(s) -
Christensson Anders,
Bruun Laila,
Björk Thomas,
Cronin Angel M.,
Vickers Andrew J.,
Savage Caroline J.,
Lilja Hans
Publication year - 2011
Publication title -
bju international
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.773
H-Index - 148
eISSN - 1464-410X
pISSN - 1464-4096
DOI - 10.1111/j.1464-410x.2010.09761.x
Subject(s) - prostate cancer , medicine , interquartile range , prostate specific antigen , prostate , urology , prostate biopsy , cancer
Study Type – Diagnostic (exploratory cohort)
Level of Evidence 2b OBJECTIVE • To assess variation of total prostate‐specific antigen (tPSA), free PSA (fPSA), percent fPSA, human glandular kallikrein 2 (hK2) and intact PSA measured three times within 2 weeks. Knowledge of the variation in an individual’s PSA level is important for clinical decision‐making. PATIENTS AND METHODS • Study participants were 149 patients referred for prostate biopsy, of which 97 had benign disease and 52 had prostate cancer. • Three blood samples were drawn with a median of 4 h between first and second samples and 12 days between first and third samples. • Variability was described by absolute differences, ratios and intra‐individual coefficients of variation. Total PSA, fPSA, hK2 and intact PSA were measured in anticoagulated blood plasma. RESULTS • At baseline, the median tPSA was 6.8 (interquartile range, 4.5–9.6) ng/mL. The intra‐individual variation was low for all biomarkers, and lowest for tPSA. For 80% of participants, the ratio between first and second time points for tPSA was in the range 0.91–1.09 and the ratio for percent fPSA was in the range 0.89–1.15. • Total coefficients of variation between time 1 and 2 for tPSA, fPSA, percent fPSA, hK2 and intact PSA were 4.0%, 6.6%, 6.0%, 9.2% and 9.5%, respectively. • The measurements taken several days apart varied more than those taken on the same day, although the variation between both time points was not large. CONCLUSIONS • The intra‐individual variation for all the kallikrein‐like markers studied was relatively small, especially for samples drawn the same day. • Few cases are reclassified between the time points. This indicates the high short‐term biological and technical reproducibility of the tests in clinical use.