Assessment of ethnic variation in serum levels of total, complexed and free prostate specific antigen. Comparison of Maori, Pacific Island and New Zealand European populations

Aims: To determine whether age-adjusted levels of serum total (tPSA) and complexed (cPSA) prostate specific antigen and the ratio of free to tPSA (%fPSA) differ by ethnic group independent of symptomatic disease.Methods: The serum levels of tPSA, cPSA, and %fPSA in relation to age, ethnicity and obstructive urinary symptoms were examined in 1405 Maori, Pacific Island and New Zealand European men in the Wellington region of New Zealand, and indicative reference range estimates produced. Participants were non-randomly selected from two study populations.Results: tPSA and cPSA increased with age while %fPSA decreased with age in all ethnic groups. Maori showed higher tPSA values in the 60-69 age group than other ethnic groups. cPSA increased more rapidly with age in Maori than in New Zealand Europeans or Pacific Islanders. %fPSA differed according to age across all three ethnic groups. The median and 5th percentile Pacific Island %fPSA values were higher in comparison to the %fPSA reference ranges of all other ethnic groups and were also higher than those reported in other studies. Once adjusted for urinary symptom score, only %fPSA in Pacific Island subjects remained significantly higher than that in New Zealand Europeans (P<0.001).Conclusions: Our study indicates that %fPSA differs by ethnicity independent of symptomatic prostate disease.