Follicular disorder Hair and nails
Last Reviewed: January, 2024
Androgenic alopecia (AGA) is a complex polygenic genodermatosis that causes progressive follicular miniaturisation and baldness in a patterned distribution.
Transgender (trans) individuals have a gender different to that presumed for them at birth. Current literature focusing on hair changes in trans individuals presume the definition of ‘trans men’ as those assigned female at birth and identifying as male.
Transgender men may choose to affirm their gender with masculinising hormone therapy which aims to increase serum testosterone concentration. Exogenous testosterone administration as a component of gender-affirming therapy can accentuate and accelerate male pattern hair loss.
The incidence of androgenic alopecia (AGA) among trans men receiving testosterone is not well established. AGA can appear within 12 months of commencing testosterone therapy and both the incidence and severity may increase with long-term use.
In one retrospective study, the mean onset of AGA in trans men was 3.25 years. However, the onset was earlier for those with a known family history of AGA.
Trans men may be prescribed testosterone therapy to stimulate the development of masculine physical features, including body and facial hair, fat redistribution towards the abdomen, muscle development, and deepening of the voice.
Testosterone conversions to dihydrotestosterone (DHT) by the enzyme 5-alpha-reductase accentuates androgen receptor activation in the hair follicles. Different body areas respond to circulating androgens differently. Specifically, scalp follicles miniaturise in the temple, frontal scalp, and vertex, while beard and body hair follicles enlarge.
There is a minimum threshold level of DHT necessary for full expression of the androgenic alopecia phenotype.
Telogen effluvium due to progressive shortening of anagen duration generally precedes miniaturisation and baldness by a number of years. While more obvious in patients with long hair, telogen effluvium may go unnoticed when the hair is short.
Baldness typically commences with frontotemporal recession, before affecting the vertex and the mid-frontal scalp. The occipital scalp retains hair even in severe cases.
The Hamilton-Norwood classification of cisgender male androgenic alopecia, which describes hair loss from type I to VII, may be applicable to transgender individuals identifying as men.
Alternatively, the Sinclair scale developed for cisgender females can also be used for trans men assigned female at birth.
The aim of managing androgenic alopecia in trans men is to minimise gender dysphoria and help achieve hair growth goals.
Treatment options are based on those available for the cisgender male population. To date, only topical minoxidil and oral finasteride are approved for AGA. Other medications are off-label. There are no studies to guide ideal dosing and frequency schedule specifically in trans men.
Some successful management strategies reported in cisgender men include:
As topical minoxidil is US Food and Drug Administration (FDA)-approved for both cisgender women and men, it may be inferred that this dosing and frequency would be effective in trans patients. Minoxidil does not have hormonal properties and does not interact with testosterone therapy.
Low-dose oral minoxidil is being increasingly used as an off-label treatment to treat AGA in the cisgender population, and could also potentially be used to treat transgender patients who are intolerant to topical minoxidil.
Finasteride is an approved therapy for AGA in cisgender men. It has also been used off-label in post-menopausal cisgender women. Finasteride selectively inhibits the 5-α-reductase type II isozyme, reducing testosterone conversion into dihydrotestosterone (DHT) in both the scalp and serum.
To date, only one small retrospective study has focused on managing androgenic alopecia in trans men. It demonstrated improvement in the Hamilton-Norwood scale by one grade after an average of 5.5 months of oral finasteride. Serum testosterone levels remained within recommended limits during the study. More research on oral finasteride and its subsequent effect on sexual function and libido in trans patients are required. Gynaecomastia is a potential side effect, which may have implications for gender affirmation. Additionally, as finasteride has been associated with depression and suicidal ideation in cisgender men, thorough discussion of treatment and any pre-existing mental health disorders is important.
Topical finasteride is approved by the European Medicines Agency (EMA), but not the FDA, for male AGA. Non-inferiority compared to oral finasteride 1 mg daily has been demonstrated. Despite serum absorption, adverse sexual side effects appear to be surprisingly uncommon.
No studies have been undertaken to establish the efficacy and safety of low-level laser light therapy, micro-needling, or platelet-rich plasma for AGA in trans men. The mechanisms of action for these treatment methods are not fully understood. None of them are thought to interact with hormone therapy.
Micro-needling has been promoted as a way to improve hair growth in cis men and cis women with androgenic alopecia. It is minimally invasive and includes multiple fine needles used to create micro-punctures in the skin to stimulate injury.
Platelet-rich plasma contains autologous platelet-derived, insulin-like, epidermal, and other growth factors which can promote hair regeneration. Although hair growth has been described in case-series of cisgender patients, there is a lack of standardisation of dosing as well as the centrifugation process. The recommended quantity and frequency of treatments still need to be determined.
There are limited studies assessing how androgenic alopecia affects quality of life in trans men. More research is needed into the epidemiology and management of AGA in this population.
