Sex hormones link to heart risk

Men are more prone to – and likely to
die of - heart disease compared with women of a similar age – and sex
hormones are to blame, according to a new University of Leicester led
study

The findings of a study by Dr Maciej
Tomaszewski, New Blood Lecturer in Cardiovascular Medicine in the
Department of Cardiovascular Sciences at the University of Leicester,
suggest that this "male disadvantage" may be related to the
sex-specific effects of naturally occurring sex hormones.

The research by Dr Tomaszewski and his
colleagues, which has been published on line in the journal
Atherosclerosis, involved 933 men aged, on average, 19 years, from the
Young Men Cardiovascular Association study. The researchers looked at
ways that the sex hormones - estradiol, estrone, testosterone and
androstenedione - interacted with three major risk factors of heart
disease (cholesterol, blood pressure and weight).

They found that two of these sex
hormones (estradiol and estrone, called together estrogens) are linked
to increased levels of bad cholesterol (LDL-cholesterol) and low levels
of good cholesterol (HDL-cholesterol) in men.

This suggests that certain sex hormones
may be important risk factors of heart disease in men, even before they
present symptoms of coronary artery disease or stroke.

Dr Tomaszewski commented: "We
hypothesised that circulating concentrations of sex hormones were
associated with cardiovascular disease risk factors in men long before
any apparent manifestations of cardiovascular disease such as stroke or
myocardial infarction".

"We examined associations of
circulating estrogens (estradiol and estrone) as well as androgens
(testosterone and androstenedione) with major cardiovascular risk
factors (lipids, blood pressure, body mass) in 933 young (median age –
19 years), apparently healthy men.

"Our studies showed that one of the sex
hormones - estradiol - was associated positively with total cholesterol
and negatively with HDL-cholesterol. Circulating concentrations of
another sex hormone - estrone - showed strong positive associations
with both total cholesterol and LDL-cholesterol.

"Thus, men with the highest
concentrations of estrone and estradiol may have the highest level of
cardiovascular risk as their levels of detrimental LDL-cholesterol are
high whilst their cardio-protective HDL-cholesterol is low.

"Most importantly, the demonstrated
associations between cholesterol and estrogens were independent of
other sex hormones (testosterone and androstenedione), age, body
weight, blood pressure and other potential confounding factors.

"Our data suggest that higher levels of
estrogens may have negative influence on lipid profile in men early in
life, before the apparent onset of cardiovascular disease.

"Why natural endogenous estrogens that
are generally seen as cardio-protective in women increase
cardiovascular risk in men remains to be elucidated. Future prospective
studies are needed to confirm that higher levels of endogenous
estrogens in youth increase the risk of heart disease later in man's
life.

"A number of other investigations on
sex-specific aspects of cardiovascular disease are in progress in our
Department and I am sure that we will be able to continue providing
information in this area of research in the future."