Has blood volume an impact on serum PSA levels?

Prostate-specific antigen (PSA) is measured in circulating blood volume (BV), which is known to have a wide inter- and intraindividual variability. As data investigating the potential impact of different BV on PSA test validity are scant, we determined the relationship between BV and serum PSA values.

Men aged 41-60 years, participating in a health screening project, were evaluated. Serum samples of fasting patients were drawn between 8.00 and 10.00 a.m., all PSA measurements were determined in the same laboratory. Circulating BV was calculated according to the Retzlaff formula based on height, weight and haematocrit.

A total of 400 men with a mean age of 47.9 years entered the analysis. Mean PSA was 1.20 ng/ml (range 0.23-8.59 ng/ml) and mean BV was 3,370 ml (range 2,380-4,220 ml). Mean PSA values stratified from lowest to the highest third of BV were 1.22, 1.17 and 1.19 ng/ml in the total cohort. The respective figures for men aged 41-50 years were 1.08, 0.98 and 1.03 ng/ml, and for those aged 51-60 years: 1.47, 1.48 and 1.53 ng/ml. Neither BV nor three other related biometrical parameters (body mass index, waist-hip ratio, body fat percentage) revealed a correlation with the PSA values.

Our data suggest that BV does not have a significant impact on serum PSA values. To exclude a potential minor impact of BV on PSA, larger study cohorts, however, are required.