Hormone therapy: definition, procedure and areas of application

Objectives of gender-affirming hormone therapy

The overarching objectives of the GAHT are:

• Alignment of physical appearance to gender identity.
• Alleviation or resolution of gender dysphoria: The distress caused by the discrepancy between one’s assigned sex and one’s gender identity.
• Improving mental wellbeing and quality of life.
• Supporting social transition in the gender roles they embody.

Eligibility criteria and indications: Who can start GAHT?

The start of GAHT requires careful diagnosis and assessment of indications by an experienced, interdisciplinary team, typically comprising psychotherapists, psychiatrists and endocrinologists. Current medical guidelines, such as the „Standards of Care“ published by the World Professional Association for Transgender Health (WPATH), provide guidance in this regard.

Key aspects are usually:

• Diagnosis of gender incongruence (often accompanied by gender dysphoria).
• Comprehensive psychotherapeutic support and counselling: To consolidate gender identity, enable informed decisions and address any associated mental health conditions. A psychotherapeutic assessment (letter of indication) is often required before hormone therapy can begin.
• Capacity to give informed consent: The person must understand the implications of the treatment, its effects and any potential risks.
• Age: In the case of minors, special duties of care apply, and the consent of those with parental responsibility, as well as close supervision, is often required (see also ‘puberty block’).
• Exclusion of medical contraindications: Certain pre-existing conditions may be a contraindication to hormone therapy or may require a dose adjustment or closer monitoring.

Feminising hormone therapy: For trans* women and non-binary people (MtF spectrum)

Feminising hormone therapy aims to develop female secondary sexual characteristics and suppress male ones.

Hormones used

• Oestrogens: Estradiol (a bioidentical oestrogen) is usually used. It is responsible for the development of many female characteristics.
• Antiandrogens: These medicines block the effects of male hormones (androgens such as testosterone) or reduce their production. Common active ingredients include: Spironolactone (also has a diuretic effect), Cyproterone acetate (CPA) (a potent antiandrogen which also has oestrogenic properties; due to potential side effects, it is often used only in low doses or for a limited period), GnRH analogues (gonadotropin-releasing hormone analogues) (can effectively suppress testosterone production in the testicles).

Expected physical effects of feminising therapy

The effects become apparent gradually over months and years:

• Breast development: The growth of breast tissue is usually the first and one of the most noticeable changes. The extent of this varies from person to person.
• Fat redistribution: Body fat tends to be distributed in a more ‘feminine’ way (e.g. more on the hips and thighs, less around the abdomen).
• Skin changes: The skin often becomes softer and less oily.
• Reduction of body and facial hair: Hair growth may become slower and the hair finer. Additional treatments (e.g. laser treatment, electrolysis) are often required for permanent hair removal.
• A reduction in muscle mass and physical strength.
• A change in body odour.
• Decreased libido and spontaneous erections, testicular atrophy.
• Voice changes: Oestrogens have no significant effect on the voice, which has already deepened as a result of testosterone. To achieve a higher pitch, speech and language therapy or voice-adjusting surgery is often necessary.
• Psychological effects: Often an improvement in well-being and emotional changes.

Potential risks and side effects of feminising therapy

• Thromboembolic events (blood clots): The risk is particularly high with oral oestrogens and at higher doses. Transdermal administration (patches, gel) is considered to carry a lower risk.
• Cardiovascular diseases: Possible effects on blood pressure and blood lipid levels.
• Liver function tests: These factors can be influenced; regular checks are important.
• Prolactinoma: In rare cases, benign tumours of the pituitary gland may develop that produce prolactin.
• Mood swings, headaches.
• Weight gain.
• Reduced fertility or infertility (see the section on fertility).

Masculinising hormone therapy: For trans* men and non-binary people (FtM spectrum)

Masculinising hormone therapy aims to develop male secondary sexual characteristics and suppress female ones.

Hormones used in masculinising therapy

• Testosterone: This is the main hormone used. It is responsible for the development of male characteristics.

Expected physical effects of masculinising therapy

Here, too, the effects become apparent gradually over months and years:

• Voice deepening (voice break): This is usually one of the first and most noticeable changes. It is generally irreversible.
• Increased facial and body hair growth (beard growth). The extent of this is genetically determined.
• Absence of menstruation (amenorrhoea): This usually occurs within a few months.
• Clitoral enlargement (clitoral hypertrophy).
• Increase in muscle mass and physical strength.
• Fat redistribution: Body fat tends to be distributed in a more male-typical pattern (e.g. more around the abdomen, less on the hips and thighs).
• Skin changes: Your skin may become oilier, and acne may develop or get worse.
• A change in body odour.
• Increased libido.
• Male pattern hair loss (androgenetic alopecia) may occur if there is a genetic predisposition.
• Psychological effects: Often an increase in energy levels and an improvement in well-being.

Potential risks and side effects of masculinising therapy

• Polycythaemia (erythrocytosis): An increase in red blood cells, which can make the blood thicker and increase the risk of blood clots. Regular blood tests are important.
• Effects on liver function tests.
• Acne.
• Androgenetic alopecia.
• Sleep apnoea may improve or worsen.
• High blood pressure, adverse changes in blood lipid levels.
• Mood swings, irritability, aggression (rare, often dose-dependent).
• Vaginal atrophy (Atrophy of the vaginal mucosa).
• Reduced fertility or infertility (see the section on fertility).

Puberty blockers (GnRH analogues): An option for young trans* people

For young trans* people who have not yet reached puberty or are in the early stages of puberty, treatment with GnRH analogues (puberty blockers) may be an option. These medicines suppress the release of the body’s own puberty hormones, thereby preventing the development of the secondary sexual characteristics associated with the sex assigned at birth.

This gives young people more time to explore their gender identity and to make an informed decision about future gender-affirming hormone therapy. The effects of puberty blockers are reversible; once they are stopped, puberty begins as normal. This treatment requires particularly careful interdisciplinary support.

Forms of administration of hormones

The hormones can be administered in various ways:

• Oestrogens: Oral (tablets), transdermal (patches, gel), and, less commonly, injections.
• Antiandrogens: Usually taken orally (tablets). GnRH analogues as depot injections or implants.
• Testosterone: Usually as a gel to be applied to the skin or as injections (short- or long-acting). Less commonly, tablets (due to the potential strain on the liver) or patches.

The choice of dosage form depends on medical factors, individual preferences and tolerability.

Monitoring and medical supervision during the GAHT

Gender-affirming hormone therapy requires close and long-term medical supervision by an experienced endocrinologist or another doctor specialising in transgender health.

Regular check-ups include:

• A discussion about well-being and possible side effects.
• Physical examination.
• Blood tests: Monitoring of hormone levels (oestradiol, testosterone, and, where applicable, prolactin, LH, FSH); Assessment of blood count, liver function, kidney function, blood lipid levels and blood glucose; specific checks depending on medication (e.g. potassium whilst on spironolactone, prolactin whilst on CPA).
• Bone density measurement (particularly in the case of long-term anti-androgen therapy or testosterone deficiency).
• Preventative medical check-ups in accordance with the recommendations for one’s gender identity and taking into account the organs present.

Timeframe: When can changes be expected?

The physical changes brought about by GAHT develop gradually over months and years. It is an individual process that requires patience.

The first changes (e.g. skin changes, initial breast tenderness in MtF; voice changes, oilier skin in FtM) can often be noticed within the first 3–6 months.

It may take 2–5 years, or even longer, for many characteristics (e.g. breast development, beard growth) to reach their full development.

Your treatment team will let you know how long each stage is likely to take.

Fertility: An important consideration before starting treatment

Gender-affirming hormone therapy usually has a significant impact on fertility and can lead to permanent infertility.

• Feminising therapy: Inhibits sperm production.
• Masculinising therapy: Leads to a failure to ovulate and a lack of menstruation.

It is of crucial importance that the issue of fertility and the options for preserving fertility (e.g. cryopreservation of sperm, eggs or embryos) are discussed in detail with the treatment team before starting hormone therapy, if there is a desire to have children in the future or if this cannot be ruled out.

The role of the GAHT in the overall transition process and in relation to operational steps

For many trans* people, hormone therapy is a fundamental step towards bringing their bodies into line with their gender identity. The changes brought about by the hormones (e.g. breast development, fat redistribution, facial hair growth) can have a significantly positive impact on their self-image and how they present themselves in society.

Furthermore, hormone therapy often creates the physical conditions or a better foundation for any gender-affirming surgery that may be desired. For example, breast development induced by oestrogen can lay the groundwork for subsequent breast augmentation, whilst the masculinisation of the upper body achieved through testosterone can facilitate a mastectomy for trans* men or lead to a more harmonious outcome. Hormone therapy and surgical procedures are therefore often closely interlinked aspects of an individual’s transition journey.

Important: The decision for or against hormone therapy and/or surgical procedures is highly personal. There is no single „right way“ to transition. Comprehensive information and support are crucial.