Prostate‐specific antigen: Establishment of the reference range for the clinically normal prostate gland and the effect of digital rectal examination, ejaculation, and time on serum concentrations

This study investigated the serum prostate‐specific antigen concentration in 100 healthy men (mean age, 26.3 years; range, 20–29 years) with a clinically normal prostate gland. The effect of digital rectal examination and ejaculation on the serum concentration, and the variability of the serum concentration over 1‐week and 1‐month periods were examined. In the 100 subjects, the serum prostate‐specific antigen concentration ranged from less than 0.1–2.6 ng/ml. The mean, median, and mode were 0.68 ng/ml, 0.6 ng/ml, and 0.4 ng/ml, respectively. The 97.5th percentile value was 2.1 ng/ml. The mean and median changes in the serum concentration after digital rectal examination were −0.013 ±0.11 ng/ml and 0.0 ng/ml, respectively (P = 0.59 compared with control group). The mean change after ejaculation was 0.05 ±0.12 ng/ml, and the median change was 0.0 ng/ml (P = 0.14 compared with control group). Diurnal variation showed minimal change in 16 patients over a 1‐week period. The mean change (p.m. value ‐ a.m. value) was 0.003 ng/ml (range, −0.2–0.06 ng/ml). In addition, the serum concentration showed minimal intrapatient variability in 20 patients throughout a 1‐month period; the average coefficient of variation (standard deviation/mean) in these subjects was 16.5% (range, 6.4–45.2%). These results indicate that the range in the serum concentration of prostate‐specific antigen for healthy men with a clinically normal prostate gland is significantly lower (0.0–2.6 ng/ml) than the currently employed range (0.0–4.0 ng/ml; Tandem‐R PSA assay); in addition, digital rectal examination and ejaculation have no significant effect on the serum concentration. Finally, the time of day has little effect, and the variability in the serum concentration of prostate‐specific antigen over a 1‐week and 1‐month interval is minimal.