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- Title
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.
- Authors
Christensson, Anders; Bruun, Laila; Björk, Thomas; Cronin, Angel M.; Vickers, Andrew J.; Savage, Caroline J.; Lilja, Hans
- Abstract
OBJECTIVE • To assess variation of total prostatespecific 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 shortterm biological and technical reproducibility of the tests in clinical use.
- Subjects
PROSTATE-specific antigen; KALLIKREIN; PROSTATE cancer; BIOPSY; BLOOD; BIOMARKERS
- Publication
BJU International, 2011, Vol 107, Issue 11, p1769
- ISSN
1464-4096
- Publication type
Article
- DOI
10.1111/j.1464-410X.2010.09761.x