Gender identity disorder

Gender identity disorder is where a person is deeply unhappy with the gender they were born in, because it is different from the gender they feel they should be. This often leads to a desire to live in their preferred gender and change their appearance.

Relevant terms associated with gender identity disorder

Gender dysphoria; transsexualism; male to female (MtF) transsexual; female to male (FtM) transsexual; trans man; trans woman; transman; transwoman

What is gender identity disorder?

Gender identity disorder is a strong and persistent feeling that a person has the wrong gender identification, which causes discomfort with their sex or a sense of inappropriateness in the gender role of that sex. 

In addition, a person with this disorder wants to live and be accepted as a member of the opposite sex and change the gender of his or her body as far as possible through surgery and hormone treatment.

What causes gender identity disorder?

The underlying cause for gender identity disorder is unknown. In animals, it is known that there are critical periods of time during pregnancy where alterations in the amount of oestrogen and testosterone in the developing animal can permanently alter masculine or feminine behaviour. However, more research is needed to find out if a similar mechanism could be operating in gender identity disorder.

What are the signs and symptoms of gender identity disorder?

Gender identity disorder is the feeling that a person does not belong to the sex in which they were born. In gender identity disorder, the person is unhappy in their present gender role. In transsexualism, they also generally want to take steps to change their body through hormones and/or surgery so that it is more in keeping with the way they feel it should be. These feelings often lead to the wearing of clothes of their desired gender and changing their role in society accordingly.

People with gender identity disorder have normal body appearances and hormone levels for their birth gender.

It is important to recognise the difference between gender identity disorder, where the person feels they were born in the wrong gender, and disorders of sex development. This term covers a range of conditions present from birth, where the development of one or more components of anatomical, chromosomal or gonadal sex is unusual, but the person generally does not feel they have been born in the wrong gender.

How common is gender identity disorder?

Gender identity disorder is estimated to occur in 1 in 12,000 men and 1 in 30,000 women.

Is gender identity disorder inherited?

There is no evidence of an inherited cause for gender identity disorder.

How is gender identity disorder diagnosed?

The diagnosis and treatment of gender identity disorder is usually made in accordance with the World Professional Association of Transgender Health guidelines, which recommend that this is done by a mental health practitioner who has experience in working with clients who have problems of gender and sexuality.

A diagnosis of gender identity disorder can only be made if the person has had these feelings about their gender and sexuality for at least 2 years and the person does not have a significant mental health issue such as psychosis that could be causing the gender dysmorphia. People with mental health issues can be treated, but they require careful assessment to ensure the gender identity disorder is not related to the underlying mental health issue.

Within the NHS, the route to treatment is for a person to be assessed by local psychiatric services and, if gender identity disorder is present, refer them on to one of the specialist gender identity clinics.

Blood tests to rule out any endocrine problems are usually taken before hormone treatment is given and will test levels of luteinising hormone (LH), follicle stimulating hormone (FSH), testosterone, oestradiol and prolactin in the bloodstream. Tests may also be taken to check the person’s number and appearance of their chromosomes (karyotype), particularly if the person is young. Tests will also be taken to make sure it is safe to give hormones, and these include liver function tests, a prostate-specific antigen test and a full blood count. 

How is gender identity disorder treated?

The whole treatment process is known as triadic therapy, which is a progressive strategy, consisting of three critical elements – ‘real-life experience’, hormonal therapy of the desired gender and finally, sex reassignment surgery. As the person advances through this sequence of therapy with increasingly irreversible effects on their body (and therefore, more significant physical alterations), it becomes increasingly difficult to revert to their birth sex. It is therefore important that hormonal therapy is undertaken in close collaboration with a mental health professional who is experienced in the assessment of people with gender identity disorder, ideally working closely with the endocrinologist to deliver treatment.

The aim of treatment is to suppress the production of the sex hormones of the person’s birth gender and to give the hormones of the desired gender in order to produce the secondary sexual characteristics of that desired gender. Following hormonal treatment, surgery is also often used to modify the genitalia and breasts to alter their appearance to that of the desired gender. This is known as gender reassignment surgery. 

After surgery, hormone treatment needs to be continued to prevent the complications of not having sex hormone production such as brittle bones (osteoporosis) or early heart disease.

For transwomen, the standard hormonal treatment used at the major NHS provider clinic is oestradiol valerate. The dose given is usually increased over time after an initial three months of therapy. A gonadotrophin-releasing hormone analogue is added to stop testosterone production. To cover the rise in testosterone levels for the first two weeks, cyproterone acetate is also given once daily. 

Other treatments can include the use of either ethinylestradiol or premarin. However, these preparations are difficult to measure and put the person at a greater risk of thrombosis of the veins than with the use of oestradiol valerate.

For transmen, testosterone treatment begins with a dose of testosterone enanthate esters 4-weekly. The dose is increased every three to four months, but initial doses are usually adequate to suppress menstruation. The aim of therapy is to achieve testosterone levels in the high normal male range one week after the injection, and to have a lower level at the bottom of the normal male range on the day the next injection is due. Other regimes include the use of testosterone gel patches or longer-acting preparations such as a long-acting injection or testosterone implants. The aim of therapy is to get the testosterone levels into the normal male range.

Are there any side-effects to the treatment?

Although side-effects are relatively rare, there are a number of issues that a person considering treatment should be aware of.

For transwomen, the side-effects can include:

  • Thromboembolic disease (deep vein thrombosis and pulmonary embolism) – the rate of deep vein thrombosis in transsexual patients is approximately 2.6%. However, in this young population, this represents a risk that is 20 times greater than that of the general population. The majority of these incidents occur during the first two years of treatment. After this period, the risk of thromboembolic disease remains, but at a much lower rate (0.4%).
  • Breast cancer – there have only been four case reports of breast tumours occurring in treated transsexual patients, suggesting that the risk of breast cancer following feminising hormone therapy is very low.
  • Hyperprolactinaemia – there may be a slightly increased risk of developing hyperprolactinaemia.
  • Abnormal liver function – the risk of abnormal liver function is approximately 3% in male-to-female transsexuals. In half of these, the abnormalities continue for more than three months. However, the increases are mild and only rarely require discontinuation of treatment.
  • Fertility – oestrogen therapy leads to suppression of sperm production. Men should be counselled that the treatment will reduce their fertility and offered the chance of sperm storage if desired.

For transmen, the side-effects can include:

  • Polycythaemia – testosterone replacement can be associated with thickening of the blood (polycythaemia) and this can lead to an increased risk of stroke in some people. This can occur even in young people as both stroke and heart attacks have been reported in athletes who abuse testosterone.
  • Abnormal liver function – one set of research has shown short-term increases in liver function enzymes in 4.4% of female-to-male transsexuals and this was prolonged (more than six months) in only 6.8% of these. 
  • Gynaecological malignancy – testosterone can be converted to an oestrogen (specifically to oestradiol) in the body. This is especially likely to occur when high levels of testosterone replacement are used. The reported risk of overgrowth of the lining of the womb (endometrial hyperplasia) is 15% in transmen. Monitoring of the endometrial thickness by ultrasound scanning every two years is recommended. Hysterectomy is often recommended after two years of testosterone therapy.

What are the longer-term implications of gender identity disorder?

The normal timescale for treatment is that a person has to be living in the opposite gender for a minimum of one year, but more usually two years, before they are eligible for gender reassignment surgery.

With regard to long-term outcomes, the mortality rate between the trans and general population is not different, which shows that lifelong hormone replacement therapy in this group is very safe.

The legal rights of transpeople have been recognised in the Gender Recognition Act and the majority of trans people have the right to change their birth certificate when they are stable and established in their new gender role.

Last reviewed: Mar 2018