攝護腺特定抗原是目前最廣泛使用在診斷及治療攝護腺癌的腫瘤標記。不過，目前所使用的攝護腺特定抗原在診斷早期的攝護腺癌時，缺乏令人滿意的敏感度及特異性。近年來，攝護腺特定抗原被發現以數種不同的分子型態（游離型，複合型）表現，且其比率在不同的攝護腺疾病中亦不同；例如，游離攝護腺特定抗原比率，在良性攝護腺肥大就比攝護腺癌來得高。兩百九十四位住院擬作身體檢查的正常中國男人被選為研究對象。血液標本以單株一單株免疫放射法來測定其攝護腺特定抗原總量及游離量。其游離型及總量攝護腺特定抗原分別是（0.4± 0.02；l.2± 0.09 微克/毫升），( 0.57± 0.06；1.81± 0.23微克/毫升），( 0.48± 0.03；1.64± 0.09微克/毫升）及（0.57± 0.05；1.90± 0.21 微克/毫升）在50-59歲（9人），60-69 歲（47人），70 -79 歲（125人）及50-59 歲（26人）的年齡群，而游離攝護腺特定抗原比率則分別是38.9%± 1.5%，3.6%± 1.8%，32.5%± 1.2%和33.2%± 2.0%。此外，有537位泌尿科門診病人亦接受攝護腺特定抗原總量及游離型之檢查。游離型及總量攝護腺特定抗原分別是（0.66± 0.08；2.8± 0.36 微克/毫升），( 1.11± 0.11；4.66± 0.63微克/毫升），( 1.40± 0.26；5.25± 0.89 微克/毫升），( 1.19± 0.23；4.42± 0.86 微克/毫升）在50-59 歲（140人），60-69 歲（215人），70-79 歲（147人）及80-89 歲（37人）的年齡群。而其比率分別是33.4%± 1.4% ， 31.8%± 0.9%，31.0%± 0.2%，31.6%± 1.9%。無論是體檢病人或泌尿科門診病人，游離攝護腺特定抗原比率在各年齡層都是呈現在相當恒定的範圍內。更進一步地，總量游離攝護腺特定抗原在2 .0至20.0微克/毫升的泌尿科門診病人（267人），其抗原比率亦作了分析。其游離攝護腺特定抗原比率除了在50-59歲年齡層（22.3 %）外，呈現在更恆定的範圍內( 26.4 %至27.3 %）。本研究結論是病人的年齡在60歲以上，其總量游離攝護腺特定抗原在2.0 至20.0微克/毫升之問的中國男人，其游離攝護腺特定抗原比率是相當恆定且沒有年齡層的差異性。

The purpose of this study is to determine age-specific ranges for free-to-total PSA ration in Chinese men. Hopefully, this may optimize its clinical use. Two hundred and ninety-four normal Chinese men admitted for physical check-up were en-rolled in this study. Serum samples were obtained and total PSA was measured using time-resolved monoclonal-monoclonal immunoradiometric assay (IRMA); free PSA was measured by monoclonal-monoclonal radioimmunoassay. The free PSA and total PSA values were (0.41± 0.02; 1.25± 0.09 ng/ml), (0.57± 0.06; 1.81± 0.23 ng/ml), (0.48± 0.03; 1.64± 0.09 ng/ml), (0.57± 0.05; 1.90± 0.21 ng/ml) in the 6th (n=96), 7th (n=47), 8th (n=125), and 9th (n=26) decade subject froups respectively. Interestingly, PSA ratios were 38.9%± 1.5%, 36.6%± 1.8%, 32.5%± 1.2% and 33.2%± 2.0%, respectively. Furthermore, there were 537 Urological OPD patients who received PSA and free PSA de-terminations. The free and total PSA values were (0.66± 0.08; 2.85± 0.36 ng/ml); (1.11± 0.11; 4.66± 0.63 ng/ml), (1.40± 0.26; 5.25± 0.89 ng/ml), and (1.19± 0.23; 4.42± 0.86 ng/ml) in the 6th (n=140), 7th (n=215), 8th(n=147), and 9th (n=37) decade patient groups, respectively. Sig-nificantly, the PSA ratios were 33.4%± 1.4%, 31.8%± 0.9%, 31.0%± 0.2%, 31.6%± 1.9%, re-spectively. No significant differences were demonstrated in PSA ratios in physical check-up sub-jects and Urological OPD patients. Moreover, there were 267 Urological OPD patients whose total PSA values ranged between 2.00 and 20.0 ng/ml whose serum were collected for further analysis. The PSA ratio was shown to be more consistent in each age group (from 26.4% to 27.3%) except in the 6th decade group (22.3%). In conclusion, in patients over 60 yr old, with total PSA between 2.0 and 20 ng/ml, the PSA ratio is quite constant and shows no age-specific difference in Chinese men.