Age-specific reference values for serum prostate-specific antigen in a community-based population of healthy Swedish...

To establish normal reference values for prostate-specific antigen (PSA) in a Swedish population we investigated 878 healthy men, 56-75 years of age. They were randomly selected from a population of 9171 males in this group. Cancer of the prostate was excluded by digital rectal examination. When digital rectal examination was suspicious for carcinoma of the prostate and/or serum PSA > 4 micrograms l-1, fine-needle aspiration biopsy was performed. Central values, values of variance and reference limits were defined by a non-parametric method in four age groups. A strong positive correlation between PSA values and age was found and the variance increased with age. The relationship between PSA value and age was non-linear. For the age group 56-60 the upper reference limit (95th percentile) was 4.6 micrograms l-1 (confidence interval, CI: 3.9-5.5). For the age groups 61-65, 66-70 and 71-75 the corresponding values were 4.4 (3.8-5.2), 7.6 (6.5-8.9) and 8.4 micrograms l-1 (7.2-9.8) respectively. For the age groups studied the increment over time of the PSA value was 2-8% per year depending on age, with an average increment per year over 15 years of 4.3%. Overall, 11% of our reference sample had a serum PSA level > 4 micrograms l-1. We consider our study population to be representative for a normal Swedish male population in these age groups.