Hirsutism and virilization: the Ferriman-Gallwey score and the causes

What it is

Hirsutism is excess terminal (thick, pigmented) hair in women in areas where hair growth depends on androgens, such as the upper lip, chin, chest and lower abdomen. It differs from hypertrichosis, a generalized increase of fine hair that does not depend on androgens. Virilization means stronger androgen effects, such as a deeper voice, clitoral enlargement and male-pattern balding, and suggests an androgen-secreting tumor or severe adrenal disease.

The anatomy it tests

• The pilosebaceous unit in androgen-sensitive skin turns fine vellus hair into terminal hair under androgen stimulation.
• The ovaries (theca cells) and the adrenal glands (zona reticularis) are the main sources of androgens in women.
• The pituitary drives both glands through LH (ovary) and ACTH (adrenal).
• Skin sensitivity to androgens varies, so the degree of hirsutism does not always match blood androgen levels.

How to elicit it

1. Ask when the hair appeared, how fast it is progressing, about menstrual cycles, medicines and family history.
2. Ask about hair removal, because shaving, waxing or laser can hide the real degree of hair growth.
3. Inspect nine areas: upper lip, chin, chest, upper abdomen, lower abdomen, upper arms, thighs, upper back and lower back.
4. Score each area from 0 (no terminal hair) to 4 (frank male pattern) and add the scores (modified Ferriman-Gallwey).
5. Look for other signs of androgen excess: acne, oily skin and thinning hair at the crown.
6. Look for virilization: deep voice, increased muscle mass, breast atrophy, temporal balding and an enlarged clitoris.
7. Look for clues to the cause: acanthosis nigricans, central obesity, purple striae, a moon face, and an abdominal or pelvic mass.

What a positive result means

• A score of about 8 or more is the usual threshold for hirsutism; lower cut-offs are used in some populations, including about 6 in South American women.
• Gradual onset around puberty with irregular cycles: polycystic ovary syndrome, by far the most common cause.
• Hirsutism with regular cycles and normal androgens: idiopathic hirsutism, a diagnosis of exclusion.
• Nonclassic congenital adrenal hyperplasia (21-hydroxylase deficiency) can look like polycystic ovary syndrome.
• Rapid onset over months, late onset, virilization or a palpable mass suggest an ovarian or adrenal androgen-secreting tumor; Cushing syndrome and some medicines are other causes.

Usefulness and limits

• The score is subjective and varies by ethnicity; it does not capture localized heavy growth.
• Total or free testosterone first; DHEA sulfate if an adrenal source is suspected; early-morning 17-hydroxyprogesterone for nonclassic congenital adrenal hyperplasia.
• Prolactin and TSH when cycles are irregular; tests for Cushing syndrome when its features are present.
• Pelvic ultrasound or adrenal imaging when a tumor is suspected.

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Educational content on the clinical exam; it is learned and practised under supervision. It does not replace assessment by a health professional and is not for self-diagnosis.

Sources: Hirsutism in Women (American Family Physician (AAFP), 2019); Polyendocrine Metabolic Ovarian Syndrome (PMOS) (MSD Manual Professional Edition, 2024).

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