Exogenous estrogen effect on lipid /lipoprotein cholesterol in transsexual males

Lipid/lipoprotein cholesterol values and sex-hormone-binding globulin levels were determined in 40 transsexual males aged 20–38, 20 castrated and 20 non-castrated, taking conjugated estrogens to induce female characteristics. Variables controlled included dose of estrogen, age, weight, smoking, alcohol intake, exercise and diet history. Transsexual males on estrogens had significantly higher mean (± SE) HDL cholesterol levels (69.0 ± 7.1 mg/dl) respectively, for castrated males and (53.8 ± 6.2 mg/dl) for non-castrated males, respectively compared to normal control males not on hormonal therapy (41.5 ± 5.4) (p < 0.001), regardless of dose of estrogen received. The total cholesterol/HDL ratio was 3.31–4.05 in transsexual males on estrogens compared to 5.03 for normal males (p < 0.001). Transsexual males had mean SHBG levels in the female range (63.4 to 71.8 nmol/ml), significantly higher than controls (26.7 nmol/ml) (p < 0.001). SHBG levels were correlated with estrogen use, dose and HDL cholesterol levels. We conclude that exogenous estrogens administered to transsexual males results in a female pattern of lipid/lipoprotein cholesterol and SHBG concentration. The decreased total cholesterol/HDL ratio may imply a lower atherogenic potential and a lessened cardiovascular risk in males who take estrogens.