Cookies on this website

We use cookies to ensure that we give you the best experience on our website. If you click 'Accept all cookies' we'll assume that you are happy to receive all cookies and you won't see this message again. If you click 'Reject all non-essential cookies' only necessary cookies providing core functionality such as security, network management, and accessibility will be enabled. Click 'Find out more' for information on how to change your cookie settings.

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.

Original publication

DOI

10.1111/j.1464-410X.2010.09761.x

Type

Journal article

Journal

BJU Int

Publication Date

06/2011

Volume

107

Pages

1769 - 1774

Keywords

Adult, Aged, Biomarkers, Tumor, Biopsy, Needle, Cohort Studies, Humans, Kallikreins, Male, Middle Aged, Neoplasm Staging, Observer Variation, Prostate-Specific Antigen, Prostatic Neoplasms, Sensitivity and Specificity, Sweden, Time Factors