[Sex differences in the field of laboratory medicine]

It is well-known that there are significant "sex differences" in many laboratory tests. After puberty onset, sex-specific organs are well developed and clinical tests concerning their functions show obvious sex differences. On the other hand, sex differences are minimal or negligible in other test items representing functions of organs common in the both sexes. But, there are some exceptions. While in childhood, sex steroids secretions from sex-specific organs are inhibited in both sexes, after puberty onset, differences in the amount of secretion of sex steroids increase, resulting, either in a direct or indirect ways, in sex differences of the blood levels of many laboratory tests. The mechanisms of sex differences are not clear in many test items. Indeed, sex difference in height is not necessarily completely unraveled. Further studies on mechanisms of sex differences in laboratory tests will reveal mysterious differences between men and women.