Definition and initial assessment
Hirsutism corresponds to excessive terminal hair growth in women, in androgen-dependent areas such as the upper lip, chin, chest, linea alba or back.
The first step is to confirm that this is hirsutism and not hypertrichosis. Hypertrichosis is characterised by a diffuse increase in hair growth, without a typically androgen-dependent distribution.
Red flags
Once the condition has been confirmed, it is essential to look for red flags. Rapid onset, especially within less than 6 to 12 months, marked progression, severe hirsutism or the presence of virilisation should raise suspicion of a tumoural cause.
Signs such as deepening of the voice, clitoromegaly, temporal alopecia or rapid increase in muscle mass require urgent assessment and hospital referral. In these cases, tests such as total testosterone, DHEA-S, SHBG, LH, FSH and pelvic ultrasound may be requested, but investigation should not delay referral.
Other endocrinopathies
In the absence of red flags, the possibility of other endocrinopathies should be considered according to the clinical context. Cushing syndrome, hyperprolactinaemia, acromegaly and thyroid disease rarely present with isolated hirsutism, but should be considered when suggestive signs or symptoms are present.
Assessment of severity
The next step is to assess severity. The Ferriman–Gallwey score allows hirsutism to be quantified across nine body areas. In general, values between 8 and 15 points correspond to mild hirsutism, between 16 and 25 points to moderate hirsutism, and above 25 points to severe hirsutism. The cut-off may vary according to ethnicity, so interpretation should always be clinical.
Mild hirsutism
In women with mild hirsutism, regular cycles and no other signs of hyperandrogenism, initial laboratory testing may not be necessary. Medication should be reviewed, as drugs such as danazol, anabolic steroids, ciclosporin, minoxidil, phenytoin, systemic glucocorticoids, tamoxifen or clomiphene may contribute to the condition.
When to request laboratory testing
If hirsutism is moderate or severe, progressive, or associated with menstrual irregularity, acne, androgenetic alopecia, obesity, acanthosis nigricans or infertility, laboratory testing should be considered. This may include total testosterone, SHBG, LH, FSH, DHEA-S and 17-hydroxyprogesterone, as well as pelvic ultrasound.
Very high testosterone levels, particularly above 6.94 nmol/L, suggest a tumoural origin and warrant hospital referral. A 17-hydroxyprogesterone level above 6 nmol/L suggests non-classic congenital adrenal hyperplasia.
Polycystic ovary syndrome
The most common cause of hirsutism is polycystic ovary syndrome, accounting for around 70 to 80% of cases. Diagnosis is based on the Rotterdam criteria: ovulatory dysfunction, clinical or biochemical hyperandrogenism, and polycystic ovaries on ultrasound. At least two criteria are required, after exclusion of other causes.
Idiopathic hirsutism
When criteria for polycystic ovary syndrome are not met and no other cause is identified, the diagnosis may be idiopathic hirsutism, which accounts for around 5 to 15% of cases.
Treatment
Treatment depends on severity, the impact on the patient and reproductive plans. In women with excess weight, weight loss should be encouraged, particularly in the context of polycystic ovary syndrome.
In women who do not wish to become pregnant, first-line pharmacological treatment is combined hormonal contraception. Response is slow and should only be assessed after at least 6 months. If response is insufficient, anti-androgens such as spironolactone or finasteride may be considered, always with effective contraception because of the potential fetal risk.
For facial hirsutism, topical eflornithine may be used as an adjunct, slowing hair growth.
Summary
In summary, the approach to hirsutism involves confirming the androgenic pattern, excluding red flags, assessing severity, investigating common causes such as polycystic ovary syndrome, and defining a progressive, safe treatment plan adapted to the patient’s priorities.
