Androgenetic alopecia

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Meet the patient

A 32-year-old man sits down, hat in hand, and turns to show a deepening bitemporal recession and a thinning vertex his barber flagged six months ago. His maternal grandfather, he tells you, was bald as an egg by thirty-five. He has read the internet and has come in asking for finasteride today.^[1][2]

Two questions decide this consultation, and they are the two every AGA stem turns on: is this really androgenetic alopecia and not a mimic? (the dermatoscope answers in ninety seconds), and is he safe for the drug he is asking for? (a quick history, a baseline PSA, and a straight warning about mood). Hold those two questions and the rest of the page slots into place.^[1]

What it is — and the one sign that rules it in or out

AGA is a genetically determined, androgen-dependent, progressive miniaturisation of susceptible scalp follicles — and it is non-scarring. That last word is the whole exam. The follicle shrinks but it does not die, and the follicular ostium stays open on trichoscopy. Lose the ostia and you are no longer in AGA — you are in cicatricial (scarring) alopecia, and the management changes completely.^[1][7]

The single most useful bedside sign in all of hair-loss medicine is preserved versus lost follicular ostia. Put a dermatoscope on the scalp. If you see hair openings — even empty ones — sitting beside hairs of mixed calibre, you are looking at AGA. If the scalp is smooth, shiny, and porcelain, with the follicular markings gone, the diagnosis is scarring alopecia and you biopsy the edge before reaching for minoxidil.^[1]

The terminology rewards precision, and examiners pay for it:^[1]

• Male pattern hair loss (MPHL) — Hamilton-Norwood, seven stages with substages.
• Female pattern hair loss (FPHL) — Ludwig (three grades) and the Olsen Christmas-tree variant.
• Pattern hair loss (PHL) — the modern gender-neutral umbrella.
• Diffuse unpatterned alopecia (DUPA) — uncommon, severe, often hyperandrogenic; biopsy to confirm.^[2]

Within the non-scarring alopecias, AGA is separated from telogen effluvium by hair diameter diversity over 20 percent — telogen effluvium thins every hair uniformly, while AGA leaves thick and thin hairs standing side by side in the same field.^[1][2]

Read the pattern: Hamilton-Norwood or Ludwig?

The pattern is so characteristic that diagnosis is clinical. Men lose the bitemporal hairline and the vertex; women keep the frontal hairline and widen the central part. Name the system, then name the stage.^[1][2]

^[1]

Hamilton-Norwood, reproduced verbatim: I minimal bitemporal recession; II symmetric triangular bitemporal (up to 2 cm anterior to the coronal suture); III deep bitemporal (III vertex adds early vertex thinning); IV frontal and vertex thinning separated by a band; V the band narrows; VI the band disappears into confluence; VII only the occipital horseshoe rim remains.^[2][7]

Ludwig, with the frontal hairline as the discriminator: I a widened midline part with scalp visible through parted hair; II a clearly widened part with thinning visible without parting; III the full crown visible — and the frontal hairline preserved in every grade. The Olsen Christmas-tree variant layers a frontal accentuation along the part on top of the Ludwig grade.^[1][7]

The histological signature on horizontal scalp biopsy is a terminal-to-vellus ratio below 4:1 (normal scalp runs 7–9:1) — diagnostic when the clinical picture is genuinely uncertain.^[7]

^[1]

How common, and who is at risk?

AGA is near-universal in susceptible ageing populations, but prevalence, onset, and severity track sex, ethnicity, and genetics. Men present in their late teens to twenties — about one in four by thirty, half by fifty. Women usually notice thinning in the perimenopausal forties-to-fifties, though PCOS and hyperandrogenism pull the onset into the twenties.^[2][8]

^{[2] [8]}

Ethnic variation. Prevalence is highest in Caucasians, intermediate in Asians, and lowest in Africans. Asian men show less bitemporal recession and more diffuse frontal and vertex thinning; the African occipital halo of DHT-resistant follicles is robust. African women carry more traction-related marginal (often cicatricial) alopecia and less FPHL, though androgenic contribution to frontal fibrosing alopecia is increasingly recognised.^[2][8]

Genetics — the maternal grandfather is not a myth. The androgen receptor gene sits on Xq12, inherited through the maternal line. The CAG repeat length in exon 1 sets AR activity — shorter repeats, more active receptor, more AGA. SRD5A2 polymorphisms tune DHT output; WNT-pathway genes (WNT10A, LEF1) set follicular fate. Inheritance is polygenic, so the paternal line contributes too — but the bedside tradition of asking about the maternal grandfather has a chromosomal basis.^[1][2]

The link the examiner now expects: early AGA and the heart

Early-onset AGA in men (before age 25) is an established cardiovascular risk marker, not a cosmetic footnote. It associates with insulin resistance, metabolic syndrome, dyslipidaemia, hypertension, and type 2 diabetes, independent of BMI — roughly a two- to threefold rise in metabolic-syndrome risk. The link runs both ways: hyperinsulinaemia suppresses sex-hormone-binding globulin, raising free androgen availability and accelerating follicular miniaturisation.^[12][13]

This does not change how you treat the hair, but it changes the consultation. A young man with an aggressive Norwood III at twenty-three deserves a fasting glucose, a lipid panel, and a blood pressure — not just a prescription. Recent sex-stratified propensity-matched cohort data confirm the cardiometabolic comorbidity.^[12][13]

Why the follicle shrinks — DHT, not testosterone

The lay story that testosterone causes baldness is wrong. Testosterone alone does not miniaturise follicles. Its reduced metabolite, dihydrotestosterone (DHT), does — and only in follicles carrying a permissive androgen-receptor signature. DHT binds the AR with roughly five times the affinity of testosterone; the activated complex enters the nucleus and rewires the dermal papilla.^[1][2][7]

Run cascade way the examiner wants it:^[1][2][7]

1. Testosterone enters the dermal papilla of a susceptible follicle and is reduced to DHT by 5-alpha-reductase.
   • Type I (SRD5A1) — skin, sebaceous glands, liver.
   • Type II (SRD5A2) — prostate, hair follicle, beard, liver. This is the one finasteride hits.
2. DHT binds the AR, the complex dimerises and translocates to the nucleus, and gene expression shifts.
3. The dermal papilla secretes paracrine effectors — TGF-β1 and TGF-β2, DKK-1 (a WNT antagonist that blocks anagen entry), PGD2 (via lipocalin-type PGD synthase, acting on GPR44/DP2), and IL-6 — that tell the overlying matrix cells to shorten anagen and shrink the bulb.
4. Across cycles the follicle produces a thinner, shorter, paler vellus hair; the anagen-to-telogen ratio falls from about 9:1 toward 2:1.
5. The follicle becomes clinically invisible — but it does not die, which is why transplantation works.
6. Occipital and lateral-temporal follicles are DHT-resistant (lower local 5-AR Type II, a different AR co-regulator milieu) — they form the donor horseshoe of Norwood VII.^[1]

^[1]

Etymology for viva gold: alopecia comes from the Greek alopēx, fox — foxes shed and go bald with mange, and the metaphor stuck for two and a half millennia. Androgenetic fuses andros (man) with genesis (origin): the hair loss is born of androgens. Both roots outlived their literal meanings because the pathology they name is unchanged.^[1]

^[1]

Why occipital escapes — donor dominance

Occipital and lateral-temporal follicles keep their terminal calibre even in Norwood VII. The molecular reason is lower local 5-AR Type II activity and a different AR co-regulator milieu, with higher WNT agonism. The clinical consequence is the single most useful idea in transplant surgery: donor dominance — an occipital follicle transplanted to a balding vertex keeps behaving as occipital and resists DHT in its new home.^[3]

That is why the graft is permanent. But — the counselling trap — the surrounding native hairs keep thinning on schedule. Every transplant patient needs ongoing medical therapy to preserve the cosmetic result, or the permanent grafts end up as islands in a widening bald field.^[1][3]

The bedside round — two minutes, five moves

Examination in suspected AGA rarely surprises you; its job is to confirm the pattern and exclude a mimic. Run it the same way every time.^[1]

1. General inspection — hair density by quadrant, the pattern of thinning, occipital preservation.
2. Hair pull test — grasp 50–60 hairs at the scalp and pull gently. More than 6 telogen hairs means positive. Best done after 5 days without shampooing. Negative in stable AGA; positive in active AGA, telogen effluvium, and alopecia areata.
3. Part-width comparison — central widening (Ludwig), frontal accentuation (Olsen Christmas-tree).
4. Hair calibre — run the fingers from frontal to vertex; reduced vertex calibre suggests AGA.
5. Follicular ostia — preserved in AGA, telogen effluvium, and alopecia areata; lost in cicatricial alopecia. This is the sign that changes everything.^[1]

Trichoscopy is the standard diagnostic adjunct — non-invasive, thirty seconds with a polarised handheld dermatoscope (ideally 20–70×), and it distinguishes AGA from every important alternative.^[1][7]

^{[1] [1]}

The mimics you must not miss — the Big Five

Every candidate on the differential must be excluded before you commit a patient to lifelong therapy, because the wrong diagnosis wastes a year and misses a treatable cause. The examiner almost always asks about at least one.^[1][2][7]

^[1]

The one-line discriminator to carry onto every ward round: diameter diversity over 20 percent with preserved ostia is AGA; uniform thinning with preserved ostia is telogen effluvium; smooth shiny scalp without ostia is scarring — and scarring is never AGA.^[1]

The classic trap: treating a cicatricial alopecia with minoxidil and missing the window for immunomodulation. Smooth shiny scalp with lost ostia is a biopsy, not a prescription.^[1]

Other mimickers worth naming: drug-induced alopecia (anticoagulants, retinoids, beta-blockers, lithium, valproate, carbamazepine, cytotoxics — diffuse and reversible on withdrawal); iron deficiency without anaemia (low ferritin worsens chronic TE and blunts the FPHL response); endocrine causes (hypo- or hyperthyroidism, hypopituitarism); nutritional deficiency (protein, zinc, vitamin D, essential fatty acids); the moth-eaten alopecia of secondary syphilis (VDRL/RPR positive, responds to penicillin); hypotrichosis simplex (autosomal dominant, from childhood); pressure alopecia (post-op or ICU); and traction alopecia from tight braids or weaves — reversible early, scarring late.^[1]

Investigations — keep them targeted

Most AGA is diagnosed clinically and trichoscopically; the laboratory exists to unmask mimics and to prescribe safely, never to confirm the obvious.^[1][7][8]

Baseline for everyone: full blood count and ferritin — iron deficiency was the commonest correctable cause in a 155-woman alopecia series, where deficiency was defined as serum ferritin under 60 ng/mL and the level considered adequate for hair growth was 40–60 ng/mL — plus thyroid testing (thyroid disease accounted for 7.7% of that series) and vitamin D, zinc, and B vitamins, whose deficiencies act as modifiable risk factors, though the trial evidence is not entirely consistent. Correct a documented deficiency; that is the rational target.^[24][4]

Female hyperandrogenism screen — if hirsutism, acne, irregular menses, or central obesity accompany the thinning, keep the work-up targeted and interpret it with humility: in a 106-woman FPHL cohort that analysed sex, adrenal, and thyroid hormones plus iron metabolism, 40% reported menstrual disorders, hirsutism, or acne — yet hormone tests showed no significant abnormalities. The tests that surfaced findings were SHBG (raised in 38.8%), total testosterone (low in 25.4%), anti-TPO antibodies (raised in 17.3%), DHEA-S (low in 15.6%), and insulin (raised in 12.6%); free testosterone was raised in only 6.8%.^[25]

Pelvic ultrasound when PCOS is on the table: polycystic ovarian morphology is currently defined as an antral follicle count of at least 20 per ovary or an ovarian volume over 10 mL on transvaginal ultrasound.^[26]

Before finasteride or dutasteride in men: liver function tests as baseline, and a baseline PSA — because these drugs halve it. Consider documenting baseline sexual function (IIEF-5) for monitoring.^[1]

When to biopsy. Reserve the 4-mm punch for genuinely uncertain cases — typically a suspected DUPA or a possible cicatricial mimic. The AGA signature on horizontal section is a terminal-to-vellus ratio below 4:1, a normal-to-slightly-raised telogen count, preserved ostia, and a mild perifollicular lymphocytic infiltrate.^[1][7]

Alopecia emergencies — when AGA is not the diagnosis

AGA itself is never an emergency, but its differential contains several that are. The examiner rewards recognition above management.^[2]

^{[27] [28] [29] [5] [14] [15] [10]}

Treatment — match the drug to the sex and the stage

AGA therapy is longitudinal and lifelong: response guides every adjustment, and withdrawal reverses the benefit within 3–6 months. The clinician who discusses adherence at the first visit prevents the disappointment that arrives three years later.^[1][3][5][6]

^{[1] [5] [7]}

The drug table — doses, sex, and the one hazard each:^[5][14]

^{[6] [19] [14] [16] [18] [23] [5] [17] [20] [21] [3]}

Minoxidil — the only drug that works in both sexes

Minoxidil is a potassium-channel opener and vasodilator that prolongs anagen and enlarges the follicle — and it is wholly independent of the androgen pathway, which is exactly why it works in both sexes.^[6][10]

Topical minoxidil: the 5% foam, 5% solution, and 2% solution are FDA-approved for AGA in men and women, and minoxidil causes hair regrowth in both frontotemporal and vertex areas. For women, 5% foam applied once daily was approved in 2014 after Phase III trials showed a significant increase in target-area hair count versus placebo, with 5% foam non-inferior to the 2% solution applied twice daily — so once-daily foam is a legitimate female regimen. The 5% solution and foam do not differ significantly in efficacy from the 2% solution, and minoxidil is a prodrug activated by follicular sulfotransferase — so response varies from patient to patient.^[6][19]

Oral minoxidil (off-label): international Delphi consensus recommends starting at 1.25–2.5 mg/day in men (maximum 5 mg) and 0.625–1.25 mg/day in women (maximum 2.5 mg), with clinical response expected within 4–6 months and long-term continuation if effective and tolerated. A pooled analysis of 442 patients treated at 0.25–5 mg found hypertrichosis in 24% and pedal oedema in 2% — both dose-dependent — with postural hypotension in 1.1% and heart-rate changes in 1.3%. Serious complications including pericardial effusion are rare at alopecia doses; contraindications are pericardial disease, uncontrolled hypertension, and pregnancy, and weight with blood pressure should be checked before starting. Warn about transient shedding (16–22%) and counsel on adherence: oral dosing carries fewer application-related side effects than topical and improves compliance.^[10][14][15]

Counsel realistically. Visible improvement takes 3–6 months, maximum benefit at 1–2 years, and the commitment is lifelong — stopping reverts any gain within 3–6 months.^[1][6]

Finasteride — men only, and never in pregnancy

Finasteride is a selective 5-alpha-reductase Type II inhibitor that reduces scalp and serum dihydrotestosterone — and oral finasteride 1 mg/day is one of only two FDA-approved drugs for AGA.^[16][5]

Dose: 1 mg orally once daily. In a 48-week placebo-controlled trial of 66 men with a 48-week extension in 49, finasteride produced a net hair-count gain versus placebo of 9.2% at 48 weeks and 15.4% at 96 weeks — and the gains in hair weight were larger still (25.6% and 35.8%), meaning treated hairs also grow longer and thicker, not merely more numerous. Finasteride was generally well tolerated.^[16]

Adverse effects — name them and their approximate rates: decreased libido (~1.5%), erectile dysfunction (~1.5%), ejaculatory disorder (~1%), gynaecomastia (~0.5%). Most sexual effects are transient and resolve in 50–60% on continued therapy. Depression and suicidal ideation are rare but real — the FDA updated labelling in 2011 — and at the first sign of severe mood change you stop the drug and refer. Post-finasteride syndrome (persistent sexual, neurological, and psychiatric symptoms after stopping) is reported and litigated; the causal link remains controversial, and the FDA has not withdrawn the drug on that basis.^[1]

PSA — the number that must be doubled. In a randomised trial of 355 men aged 40–60 with male-pattern hair loss, finasteride 1 mg/day for 48 weeks lowered serum PSA by a median of 40% (men 40–49) and 50% (men 50–60). The screening correction derived for the 5 mg preparation — multiply the measured PSA by two — applies equally to the 1 mg dose. Forget this and you mask a prostate cancer.^[18]

Pregnancy — the absolute rule. Finasteride is contraindicated in pregnancy because of known teratogenicity, and women of childbearing potential who receive it for hair loss must adhere to reliable contraception. Prescribe it to men — and there is no reward for bending the rule: in 137 postmenopausal women with AGA, finasteride 1 mg/day for 12 months produced no increase in hair growth and no slowing of thinning versus placebo.^[23][22]

Dutasteride — men only, more potent, longer half-life

Dutasteride inhibits both type I and type II 5-alpha-reductase and suppresses DHT more than finasteride in serum and scalp. It is not FDA-approved for AGA, but Japan and South Korea have approved oral dutasteride 0.5 mg/day for male AGA. Head-to-head, dutasteride 0.5 mg/day significantly increased hair count and hair width versus finasteride 1 mg/day at 24 weeks in a 917-man randomised trial, with adverse events similar among groups.^[5][17]

The half-life is roughly 5 weeks (against about 4.5 hours for finasteride and about 4 hours for minoxidil) — the pharmacokinetic reason dutasteride lingers long after the last tablet. A comparative review ranks its probable efficacy above every finasteride and minoxidil dose studied: dutasteride 0.5 mg/d, then finasteride 5 mg/d, minoxidil 5 mg/d, finasteride 1 mg/d, and minoxidil 0.25 mg/d.^[5]

Spironolactone — women only

Spironolactone is an androgen-receptor antagonist (plus reduced testosterone production at higher doses), used off-label but widely for FPHL.^[7]

Dose: 100 mg/day was the comparator dose in a 24-week randomised trial of 204 women with FPHL (Sinclair grade II–V), where adverse events occurred in 18.6%. A 24-month retrospective cohort of 187 women then found doses above 100 mg/day (median 130 mg/day) delivered greater benefit than the maximum bicalutamide dose — with a better safety and monitoring profile — supporting spironolactone as a first-line systemic option for FPHL.^[20][21]

Other antiandrogens for women: bicalutamide 50 mg/day versus spironolactone 100 mg/day over 24 weeks produced greater trichoscopic improvement (hair count and shaft diameter) without significant differences in clinical endpoints, and with fewer adverse events (11.7%) — but over 24 months bicalutamide caused more laboratory abnormalities and required closer monitoring. Finasteride is not the answer in women: in two controlled studies it showed no benefit over placebo in female pattern hair loss.^[20][21][23]

Hair transplantation — permanent grafts, lifelong medicine

Transplantation surgically relocates DHT-resistant occipital and lateral-temporal follicles to balding recipient areas — and donor dominance makes the result permanent.^[3]

• FUT (follicular unit transplantation, the strip method): an occipital strip is excised, dissected into 1–4-hair follicular units, and transplanted. Leaves a linear scar; one session can move 2000–4000 grafts.
• FUE (follicular unit extraction): individual units are punched out one at a time with a 0.7–1.0 mm punch. No linear scar; more time-consuming; 2000–5000 grafts per session.^[1]

Candidacy. Stable Norwood III–VI men with adequate donor density and realistic expectations. Women with Ludwig II–III are poorer candidates — diffuse thinning reduces donor supply and recipient density. Smokers, poorly controlled diabetics, those with cicatricial or unstable disease, and those with body dysmorphic disorder are poor candidates.^[1]

Pitfalls. Shock loss of adjacent native hair (10–20%, usually temporary); donor depletion (irreversible); poor graft survival (smoking, sun, infection); a wider-than-expected FUT scar.^[1]

The counselling point that protects the result. Transplanted hairs are permanent, but native recipient-area hairs keep thinning on schedule. Every transplant patient needs ongoing minoxidil, with or without finasteride, or the permanent grafts end up as islands.^[1]

Adjuncts — evidence is variable, expectations must be modest

• Low-level laser therapy (LLLT) — laser caps and combs; photobiomodulation and follicular ATP; FDA-cleared for AGA; modest RCT benefit.^[3]
• Platelet-rich plasma (PRP) — autologous platelet concentrate injected into the scalp; growth factors (PDGF, TGF-β, VEGF, EGF) may prolong anagen; technique not standardised; useful as an adjunct.^[3]
• Microneedling — a 1.5 mm dermaroller every 1–4 weeks; micro-wounds release growth factors and enhance topical minoxidil penetration.^[3]
• Ketoconazole 2% shampoo — mild anti-inflammatory and anti-androgenic effect; reduces Malassezia. Useful adjunct.^[3]
• Cosmetic camouflage — scalp micropigmentation, hair fibres, wigs, weaves. Psychologically important.
• Micronutrients — correct iron, zinc, and vitamin D when deficient; no benefit from supplementing replete individuals.^[4]

^{[6] [19] [14] [20] [21] [16] [17] [5] [18] [23]}

The algorithm by stage and sex

Men, early pattern: first-line is finasteride 1 mg/day (one of only two FDA-approved AGA drugs) or topical minoxidil (5% foam or solution, FDA-approved), with oral minoxidil 1.25–2.5 mg/day (off-label, maximum 5 mg) as an adherence-friendly alternative or addition. The probable efficacy ranking from a comparative review runs dutasteride 0.5 mg, finasteride 5 mg, minoxidil 5 mg, finasteride 1 mg, minoxidil 0.25 mg. If finasteride underperforms: dutasteride 0.5 mg/day beat it head-to-head on hair count at 24 weeks.^[5][17][10]

Men, Norwood V–VII: combined finasteride plus minoxidil (consider dutasteride) is essential to preserve native hair; transplant is often necessary — counsel realistically about donor supply.^[1]

Women, no hyperandrogenism: topical minoxidil is the only FDA-approved therapy for female AGA — 5% foam once daily, non-inferior to 2% solution twice daily — or low-dose oral minoxidil 0.625–1.25 mg/day (off-label, maximum 2.5 mg). Correct documented iron, vitamin D, and zinc deficiency alongside.^{[7][19][10][4]}

Women, with PCOS or hyperandrogenism: treat the hair with topical minoxidil plus an off-label systemic antiandrogen — spironolactone 100 mg/day or above (first-line systemic option) or bicalutamide 50 mg/day (more laboratory abnormalities, closer monitoring) — and manage the endocrine syndrome in parallel. Pelvic ultrasound supports the PCOS diagnosis when antral follicle count reaches 20 per ovary or ovarian volume exceeds 10 mL.^{[7][21][20][26]}

Transgender and gender-diverse individuals: specialist-led care, integrated into the gender-affirming hormonal pathway (below).^[9]

The safety-critical drugs — three rules that must not be broken

Humour is off for the rest of this section. These three errors harm patients.^[1]

1. Never prescribe finasteride or dutasteride to a woman of childbearing potential. Both are Category X. DHT is required for normal male fetal external genitalia; inhibition causes ambiguous or female-appearing genitalia in a 46,XY fetus. Prescribing mandates a pregnancy test and highly effective contraception (long-acting reversible, or two forms). Pregnant women must not even handle broken tablets. Washout before conception: about 1 month for finasteride, about 6 months for dutasteride (the long half-life).^[1]
2. Always double the PSA in a man on finasteride or dutasteride. The drug halves serum PSA; an uncorrected reading masks prostate cancer.^[1]
3. Stop the drug at the first sign of severe mood change. Depression and suicidal ideation are rare but FDA-labelled for finasteride; the post-finasteride syndrome debate is ongoing but the patient-safety concern is real. Stop, document, and refer urgently.^[1]

Reassuring data on the cardiovascular question: a large 2026 TriNetX propensity-matched cohort found no increased cardiovascular hazard with oral 5-alpha-reductase inhibitors prescribed for AGA.^[11]

Special populations — tailor the pharmacology

Women of childbearing potential carry the absolute rules above. Topical minoxidil in pregnancy is Category C — defer to postpartum — and minoxidil enters breast milk, so avoid it in lactation.^[1]

Children. AGA in a child is uncommon and warrants investigation for hyperandrogenism (peripubertal PCOS, late-onset congenital adrenal hyperplasia, an androgen-secreting tumour), endocrine and nutritional causes, and genetic mimics (hypotrichosis simplex, ectodermal dysplasia, alopecia areata). Topical minoxidil is the only widely accepted pharmacotherapy (off-label); finasteride, dutasteride, and spironolactone are not consentable in children, and transplantation is inappropriate before adulthood because the donor area is not yet stable.^[1]

Elderly patients. Cardiovascular comorbidity shapes the choice: oral minoxidil is contraindicated in pericardial disease and uncontrolled hypertension, adverse effects are dose-dependent, and caution is advised in renal or hepatic impairment — so start at the low end of the range (0.625 mg in women, 1.25 mg in men) and review. Checking body weight and blood pressure before initiation is the Delphi-consensus minimum.^[14][10]

Transgender and gender-diverse individuals. AGA care is integrated into the gender-affirming pathway.^[9]

• Trans women and transfeminine individuals — estrogen-based gender-affirming hormone therapy slows or reverses AGA; finasteride may be added as part of androgen blockade.
• Trans men and transmasculine individuals — testosterone-based therapy worsens AGA in those predisposed; counsel before starting and consider prophylactic finasteride plus topical or oral minoxidil.
• Non-binary individuals — tailor therapy to hormonal goals.
• Mental-health input, peer support, and culturally competent care are essential.^[1][9]

PCOS and metabolic syndrome. About 40–70% of women with PCOS have AGA. Treat both in parallel: PCOS-specific care (metformin or inositol for insulin resistance, lifestyle, a combined OC with antiandrogenic progestin, letrozole for fertility) plus AGA-specific care (spironolactone or bicalutamide, topical or oral minoxidil). Coordinate endocrinology, gynaecology, and dermatology.^[1]

Cardiovascular and prostate disease. Finasteride and dutasteride halve PSA — double it for screening. Symptomatic BPH benefits from the same drugs at different doses. Oral minoxidil is a vasodilator; caution in heart failure, severe aortic stenosis, and recent MI.^[1][11]

Prognosis — progressive, lifelong, reversible on stopping

Untreated AGA is progressive over decades. Medical therapy slows or halts loss and may regrow hair, but it does not cure — all medical therapies are lifelong, and the benefit reverses within 3–6 months of stopping.^[1][5]

Good response: early treatment (within five years of onset, before extensive dropout), younger age, vertex and mid-frontal disease (better than bitemporal), good adherence, adequate donor supply, and no untreated underlying cause (iron, thyroid, androgen, drug).^[1]

Poor response: extensive disease (Norwood VI–VII), long-standing miniaturisation (over 10 years — many follicles may be unrecoverable), coexistent scarring, non-adherence (the commonest cause of failure), untreated hyperandrogenism, and donor depletion in transplant candidates. Spontaneous stabilisation occurs in about 10–20% of men after Norwood IV–V; most eventually continue.^[1][5]

Transplanted hairs are permanent, but native hairs keep thinning without medical therapy — the reason every transplant patient needs ongoing minoxidil or finasteride.^[1]

The mantra, and the viva honesty line

The mantra: diameter diversity and preserved ostia — then check who must not get finasteride.^[1]

^[1]

Ward-round test — four stems, thirty seconds each

Stem 1 — the man with the receding hairline and the bald maternal grandfatherShowHide

A 28-year-old man has progressive bitemporal recession over 18 months; his maternal grandfather was completely bald by thirty. What is the diagnosis, and what do you do at this visit? Model: Androgenetic alopecia with a positive family history — family history carries an odds ratio of about 2.7 for presence and 4.2 for progression of AGA in meta-analysis, and a paternal history alone raises risk (OR 2.2); smoking independently worsens it. Diagnosis is clinical, on the pattern, with trichoscopy where available. First-line is finasteride 1 mg/day plus topical minoxidil 5% (one of only two FDA-approved drugs, with a net hair-count gain of 9.2% at one year and 15.4% at two years versus placebo, and hair-weight gains of 25.6% and 35.8%); counsel on sexual and neuropsychiatric adverse effects, and remember that finasteride 1 mg/day lowers PSA by 40–50%, so the reading must be doubled in screening. Oral minoxidil 1.25–2.5 mg/day is the off-label alternative when adherence to topical is poor.^{[8][5][16][6][18][10]}

Stem 2 — the woman with central thinning, hirsutism, and irregular mensesShowHide

A 36-year-old woman has a widened midline part, mild hirsutism, irregular menses, and acne. Testosterone is mildly raised, SHBG is low-normal, and pelvic ultrasound shows polycystic ovaries. What is the unifying diagnosis, and how do you manage the hair? Model: PCOS with female pattern hair loss driven by hyperandrogenism — and a hormone profile that is often less dramatic than the clinical picture (in one 106-woman FPHL cohort, 40% had hyperandrogenism symptoms yet hormone tests showed no significant abnormalities). Manage the hair with topical minoxidil 5% foam once daily (the only FDA-approved therapy for female AGA) plus spironolactone 100 mg/day or above — doses above 100 mg/day outperformed maximum-dose bicalutamide over 24 months — with bicalutamide 50 mg/day as the alternative if closer laboratory monitoring is acceptable. Avoid finasteride: controlled studies showed no benefit in FPHL, it is contraindicated in pregnancy (teratogenic), and any woman of childbearing potential receiving it needs reliable contraception. Polycystic ovarian morphology on ultrasound (antral follicle count of at least 20 per ovary or ovarian volume over 10 mL) supports the diagnosis.^{[7][19][21][20][23][25][26]}

Stem 3 — why does the transplant work, and why does the patient still need finasteride?ShowHide

Explain donor dominance, and explain why a transplanted patient still needs medical therapy. Model: Occipital and lateral-temporal follicles carry lower local 5-AR Type II activity and a different AR co-regulator milieu, so they are DHT-resistant even in Norwood VII. Transplanted to a bald vertex, they keep that resistance — donor dominance — so the grafts are permanent. But the surrounding native hairs keep thinning on schedule, so ongoing minoxidil, with or without finasteride, is required to preserve the cosmetic result.^[3]

Stem 4 — the PSA that must be doubledShowHide

A 45-year-old man on finasteride 1 mg/day has a PSA of 1.0 ng/mL. How do you interpret it? Model: Finasteride 1 mg/day for 48 weeks lowers serum PSA by a median of about 40% in men aged 40–49, so a measured 1.0 ng/mL behaves like roughly 2.0 ng/mL. The recommended correction in prostate-cancer screening is to multiply the measured PSA by two — a rule derived for the 5 mg/day dose and confirmed by randomised trial to apply to the 1 mg/day preparation. Without the correction, finasteride can mask a prostate cancer and delay diagnosis. Communicate the correction to every clinician managing the patient.^[18]

References29ShowHide

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