By Martin Hutchinson
BBC News Online health staff in Madrid
Lesbians are more than twice as likely to suffer from a hormone-related condition, fuelling theories that hormones play a role in developing their sexuality.
Higher rates of a condition were found in gay women
Little is known about the origins of polycystic ovarian syndrome - one in ten women has the condition, which is linked to an excess of male sex hormones in the bloodstream.
Symptoms include excess hair, acne, and obesity, as well as a heightened risk of more serious health problems such as diabetes. Patients also often suffer fertility problems.
The latest research, presented at the European Society of Human Reproduction and Embryology conference in Madrid on Monday, came from a clinic which is one of only two in the UK to offer fertility treatment to lesbian women.
Doctors there noticed a "staggering" number of lesbian women, who, on investigation, were found to be suffering either from polycystic ovary syndrome, or a less serious but related condition in which their ovaries showed many of the same features, but without the external symptoms.
We do not view lesbianism as a disease that is in need of a cure
Dr Rina Agrawal, Hallam Clinic, London
The researchers found that prevalence of this symptomless condition was 80% in the lesbian women they saw, compared with just 32% of their heterosexual patients.
Full-blown polycystic ovarian syndrome was present in 38% of lesbians, and 14% of the heterosexual women.
Lead researcher Dr Rina Agrawal said that the results suggested "significantly greater" rates of hormone imbalance in the lesbian women.
She said that while there was no evidence that polycystic ovaries could be implicated as a cause of lesbianism, it was possible that this hormone imbalance could be linked to both the medical condition and sexuality.
She said: "We do hypothesize that hyperandrogenism, which is associated with polycystic ovary syndrome, may be one of the factors contributing to the sexual orientation of women.".
Previous studies have linked hormone imbalances with sexual orientation - and the possibility has been raised that exposure to higher levels of certain hormones early in life, perhaps even pre-natally, may be influential.
However, Dr Agrawal said there was no possibility that treatments for the ovary condition might be able to influence sexuality.
"We do not view lesbianism as a disease that is in need of a cure."
Dr Adam Balen, a gynaecologist from Leeds, said that the study did not prove that polycystic ovaries "caused" lesbianism - or vice versa.
He said: "Polycystic ovary syndrome is an extremely common condition - this study is not suggesting that women with this condition are more likely to be lesbians.".
However, Dr Agrawal said that the high rates of the illness among lesbian women she encountered meant that doctors should be on the lookout for its telltale signs among their lesbian patients - in order to make sure that their wider health was not at risk.
"Our study emphasizes the importance of treating these women in a non-judgemental and non-biased manner so that clinicians may offer them appropriate health advice."