Primary Causes of Hirsutism in Young Females
Polycystic ovary syndrome (PCOS) is the most common cause of hirsutism in young females, affecting approximately 4-6% of women in the general population and accounting for 70-80% of hirsutism cases. 1, 2
Definition and Pathophysiology
Hirsutism is defined as the presence of excessive terminal (coarse) hair growth in females in a male-like pattern distribution, affecting between 5-15% of women. 2
The pathophysiology involves:
- Increased androgen production and/or increased tissue sensitivity to androgens 3
- Local generation of androgens within the hair follicle (explaining why circulating androgen levels don't always correlate with hirsutism severity) 3
- Genetic predisposition affecting androgen receptor activity and 5-alpha-reductase activity 2
Common Causes of Hirsutism
Primary Causes:
Polycystic Ovary Syndrome (PCOS) - Most common cause (70-80% of cases) 1, 4
- Characterized by hyperandrogenic chronic anovulation
- Involves acceleration of pulsatile GnRH secretion, insulin resistance, and hyperinsulinemia
- Results in hypersecretion of luteinizing hormone and hyperandrogenism 1
Idiopathic Hirsutism - Second most common cause (5-15% of cases)
Less Common Causes:
- Non-classical congenital adrenal hyperplasia (21-hydroxylase deficiency) 1, 2
- Hyperandrogenic insulin-resistant acanthosis nigricans syndrome 2
- Androgen-secreting tumors (ovarian or adrenal) 1, 2
- Cushing's syndrome 1
- Medications (exogenous androgens, certain antiepileptics) 1
Diagnostic Approach
Key Clinical Features to Assess:
- Distribution and severity of hair growth 1
- Menstrual history - irregular periods suggest PCOS 1
- Associated symptoms - acne, balding, clitoromegaly 1
- Signs of insulin resistance - obesity, acanthosis nigricans 1
- Family history of similar conditions 1
Laboratory Testing:
- Total testosterone or bioavailable/free testosterone - levels >200 ng/dL suggest androgen-secreting tumor 1, 5
- DHEAS (dehydroepiandrosterone sulfate) - to rule out adrenal hyperplasia 1
- Androstenedione - levels >10.0 nmol/L suggest adrenal/ovarian tumor 1
- Glucose/insulin - fasting levels to assess insulin resistance 1
- Thyroid-stimulating hormone and prolactin - to exclude other endocrine disorders 1
Imaging:
- Pelvic ultrasound - to detect polycystic ovaries (>10 peripheral cysts, 2-8 mm diameter, with thickened ovarian stroma) 1
Treatment Approaches
Treatment should be based on the underlying cause and severity of hirsutism:
For PCOS-related hirsutism:
First-line therapy: Combined oral contraceptives to suppress ovarian androgen production 1
Anti-androgen medications:
Weight loss and lifestyle modifications for obese patients - even 5% weight reduction can improve metabolic and reproductive abnormalities 1, 3
Insulin-sensitizing agents (metformin) may help improve ovulation and reduce androgen levels 1
Cosmetic and Mechanical Methods:
- Topical eflornithine hydrochloride cream (FDA-approved for facial hirsutism) 1
- Hair removal techniques: shaving, waxing, plucking, electrolysis, laser therapy 1
Important Clinical Considerations
- Hirsutism often has significant negative psychological impact and should be addressed even when mild 2, 5
- Combined medical interventions are typically more effective than monotherapy 1
- Patients should be counseled that improvement may take 3-6 months after initiating therapy 5
- For severe or rapidly progressive hirsutism, especially with very elevated testosterone levels (>200 ng/dL), evaluation for androgen-secreting tumors is essential 1, 5
Special Populations
- Adolescents with PCOS may benefit from early intervention with anti-androgens like finasteride, especially those with endocrine co-morbidities 1
- Women with epilepsy have a higher prevalence of PCOS (10-25%) even without anti-epileptic drugs, and certain anti-epileptics may trigger or worsen hirsutism 1