为了验证类固醇５α－还原酶的人种差异性和个体差异性，作者通过对１０名中国男子体内静脉输注氚标记的睾酮（３Ｈ－Ｔ），研究睾酮的代谢廓清率（Ｔｍｃｒ）和睾酮向双氢睾酮的转化率（Ｔ→ＤＨＴ）。进一步又测定了２７例中国成年男子包皮组织的５α－还原酶Ⅰ型和Ⅱ型同功酶活性。经体表面积校正的Ｔｍｃｒ为６７７．４±７１．０（ｘ±ｓ）ｍｌ／ｈ，Ｔ→ＤＨＴ为３．０２±０．２１％。５α－还原酶Ⅰ型和Ⅱ型同功酶的酶活性分别为２２．６７±１２．４１和６０．６７±３６．５５（ｘ±ｓ）ｐｍｏｌ／ｍｇｐｒｏｔｅｉｎ／３０ｍｉｎ，变异范围分别为４．９１～５７．３７和２０．１０～１７４．８５。结果表明，中国男子与白种人５α－还原酶活性没有种族差异性。５α－还原酶同功酶活性的较大变异范围反映了个体之间存在较大的生理差异性，而不是方法学的问题。 In order to verify the ethnic differences and individual differences of steroid 5α-reductase, the authors investigated the metabolic clearance rate (Tmcr) of testosterone and testosterone to testosterone by the intravenous infusion of tritiated testosterone (3H-T) in 10 Chinese men. Dihydrotestosterone conversion (T → DHT). Furthermore, the 5α-reductase type I and type II isoenzyme activities in 27 cases of Chinese adult man’s foreskin were also determined. The corrected Tmcr of body surface area was 677.4 ± 71.0 (x ± s) ml / h and T → DHT was 3.02 ± 0.21%. The enzymatic activities of 5α-reductase type I and type II isozymes were 22.67 ± 12.41 and 60.67 ± 36.55 (x ± s) pmol / mgprotein / 30min respectively, and the variation ranges were 4.91 ~ 57.37 and 20.10 ~ 174.85. The results show that there is no racial difference between Chinese and Caucasian 5α-reductase activity. The larger variation range of 5α-reductase isoenzyme activity reflects the larger physiological differences among individuals rather than methodological issues.