Sex-related differences in hematological values. A study on the erythrocyte and granulocyte count, plasma iron and iron-binding proteins in human transsexuals on contrasexual hormone therapy.

Hematological data known or supposed to be influenced by individual sex hormones were evaluated in 18 untreated transsexuals (TS) and in 20 castrated or non-castrated TS on androgen and estrogen treatment, respectively. Profiting from a situation of clinically controlled hormonal sex-transformation it was tested, whether the circulating erythrocyte and granulocyte mass and iron metabolism are linked to a male and female sex-hormone constellation. The erythrocyte and granulocyte counts were significantly higher in untreated males and treated female-to-male TS than in untreated females and treated male-to-female TS. The unexpected finding of sex hormone-dependent granulocyte fluctuations was corroborated by parallel concentration changes of lactoferrin, a granulocyte-derived plasma protein. Iron metabolism as judged from plasma iron, total iron-binding capacity and serum ferritin was unaffected by sexual transformation. Plasma iron and the total iron-binding capacity did not differ significantly in untreated and treated TS of either type. The serum ferritin concentration, however, was significantly lower in untreated as well as in virilized females than in untreated and in feminized males, but was not significantly changed by long-term androgen or estrogen treatment. The present study demonstrates the potential of human transsexualism as a model for the study of sex-related biological processes.