Chapter 5 — Male Pattern Hair Loss

GP-Level Analogy

"Male pattern hair loss is like a lawn where certain patches of grass have been genetically programmed to respond to a particular weedkiller — dihydrotestosterone (DHT). Pour enough of that chemical over the lawn and those programmed patches shrink and disappear, while the patches at the edges remain perfectly healthy. The treatment is either to reduce the weedkiller or to encourage the grass to grow despite it."

Male androgenetic alopecia (MAGA) is the most common cause of hair loss in men globally, affecting approximately 50% of men by age 50 and up to 80% by age 70. Despite its prevalence, it remains significantly undertreated — largely because patients delay presentation and clinicians underestimate the psychological burden and the efficacy of available treatments.

For the GP, MAGA represents an opportunity to diagnose confidently, counsel accurately, and initiate evidence-based treatment without referral in the majority of cases.

Epidemiology at a glance

Prevalence

50% by age 50

~30% at age 30, ~50% at age 50, ~80% by age 80. Highest in Caucasians; lower in East Asian populations.

Onset

Can begin at 18–20

Earlier onset generally predicts more extensive eventual loss. Onset does not equal baldness — progression is highly variable.

Psychology

Significant QoL impact

Strong associations with depression, social anxiety, and reduced self-confidence — particularly with early-onset or severe loss.

Key Insight for GP

The earlier a patient presents, the more hair can be preserved. Treatment does not regrow what is lost — it maintains what remains. Early treatment is far more effective than late treatment. Prompt identification is critical.

Pathophysiology: the DHT–follicle axis

MAGA results from a genetically predetermined sensitivity of scalp follicles to dihydrotestosterone (DHT). All proven treatments target some point along this pathway.

Fig 5.1 — DHT pathway and follicular miniaturisation

Fig 5.1: The DHT pathway from testosterone to follicular miniaturisation. Finasteride/dutasteride block 5-alpha reductase (reducing DHT by 70–90%). Minoxidil prolongs anagen independently of DHT. Both treatments target different points on this pathway.

The miniaturisation process

Follicular miniaturisation proceeds over many hair cycles. With each successive cycle, the anagen phase becomes slightly shorter. Over years, a follicle that once produced a thick terminal hair (diameter >0.06 mm, pigmented) produces progressively thinner, shorter, and less pigmented hairs — ending as a vellus-like hair (<0.03 mm). This is why patients notice thinning before frank baldness.

The occipital and temporal fringe follicles lack significant androgen receptor expression. This explains why they are spared in MAGA and why they are used as donor sites in hair transplantation.

GP Analogy — DHT Sensitivity

"DHT is not abnormally high in most men with MAGA — their serum DHT is normal. The problem is that their frontal and vertex follicles have been programmed to overreact to it, like a smoke alarm that goes off when you toast bread. The alarm isn't broken — it's just set too sensitively."

Feature	Detail	Clinical implication
Key enzyme	5-alpha reductase type II (SRD5A2)	Target of finasteride (type II) and dutasteride (type I+II)
Key hormone	DHT (5× more potent than testosterone at AR)	Serum DHT levels not diagnostically useful — local sensitivity is the issue
Key receptor	Androgen receptor (AR) — overexpressed in frontal/vertex DP cells	AR gene on X chromosome explains maternal inheritance pattern
Inhibitory signal	TGF-β1 — upregulated by DHT, shortens anagen	Research target for novel therapies
Growth signal	IGF-1 — downregulated by DHT	Basis for PRP and LLLT research

The Hamilton–Norwood Classification

The Hamilton–Norwood scale (modified by Norwood in 1975) is the internationally accepted staging system for MAGA. It describes seven stages of progressive hair loss.

Fig 5.2 — Hamilton–Norwood scale: schematic top-view diagrams

Fig 5.2: Hamilton–Norwood scale. Types I–IIIv are early stages where medical treatment is most effective. Types V–VII represent advanced loss where hair transplantation may be considered alongside medical therapy.

Types I–II

Minimal recession. Prevention focus. Counselling + optional early treatment.

Types III–IIIv

Active recession + vertex thinning. Ideal stage for medical therapy.

Types IV–V

Significant loss. Medical therapy still useful. Transplant assessment appropriate.

Types VI–VII

Advanced loss. Limited medical benefit. Transplant or acceptance/camouflage.

GP Analogy — Treatment Window

"Treating MAGA is like repainting a house before the wood rots. Medical treatment preserves the paint that's still on — it doesn't restore what's already gone. Once a follicle produces vellus-only hair for several cycles, it's effectively a blank wall. The earlier you treat, the more wall you're protecting."

Clinical features

MAGA has a characteristic clinical presentation that allows diagnosis without investigations in the majority of men. The GP who knows what to look for can diagnose it in under two minutes.

Fig 5.3 — Key clinical features of MAGA (front-view examination schematic)

Fig 5.3: Clinical examination findings in MAGA. The M-shaped bitemporal recession and vertex thinning with preservation of the temporal and occipital fringe are pathognomonic. The preserved fringe reflects the absence of significant androgen receptor expression in those follicles.

Symptoms

MAGA is characteristically asymptomatic. No itch, pain, or scaling. The presence of any of these symptoms should prompt consideration of a co-existing condition (seborrhoeic dermatitis, psoriasis) or an alternative diagnosis (lichen planopilaris). The absence of symptoms does not mean the condition is not significant — the psychological impact can be profound.

Associated conditions

Association	Evidence	GP action
Cardiovascular disease risk	Vertex baldness associated with increased CVD risk in men under 55 (meta-analysis, 850,000+ men)	Assess CVD risk factors if vertex pattern, age <55
Insulin resistance / metabolic syndrome	MAGA associated with hyperinsulinaemia, especially in younger men	Check fasting glucose, lipids if early severe AGA
Seborrhoeic dermatitis	More common in men with AGA — each worsens the other	Treat seborrhoeic dermatitis as part of AGA management
Psychological impact	Depression, social anxiety, reduced QoL — particularly in early-onset (<35) and severe cases	Screen for depression; avoid minimising patient concerns

Making the diagnosis

In the majority of men, MAGA is a clinical diagnosis — the classic Hamilton–Norwood pattern with preserved occipital and temporal fringe. Investigations are rarely required but indicated in atypical presentations.

Sufficient for diagnosis

Classic presentation

Hamilton–Norwood pattern + male gender + preserved occipital/temporal fringe + family history + gradual onset + asymptomatic scalp = diagnose MAGA clinically. No investigations required.

Investigate if present

Atypical features

Diffuse loss without patterning, age <20, rapid onset, symptoms (itch, scale, pain), or examination findings suggesting alternative diagnosis.

Trichoscopy findings in MAGA

Finding	Description	Significance
Hair calibre diversity	Thick terminal + thin vellus-like hairs in same follicular unit	Pathognomonic — miniaturisation ratio >20% = diagnostic
Peripilar brown halo	Brown ring at follicular opening (targetoid sign)	Characteristic of AGA — perifollicular lymphocytic infiltrate
Single-hair follicular units	Follicular groups containing only 1 hair (normal: 2–3)	Loss of companion hairs from miniaturisation
Yellow dots	Empty infundibula filled with sebum (advanced)	Severe miniaturisation — follicle producing only vellus
Honeycomb pattern	Regular pigmented network in inter-follicular epidermis	Relatively accentuated in AGA with hair loss

Blood tests — when and what

Test	Indication	Rationale
Not routinely needed	Classic MAGA presentation in adult man	Clinical diagnosis — investigations add nothing
FBC, ferritin, TFTs	Diffuse component or atypical pattern	Exclude superimposed TE — common co-occurrence
Testosterone, SHBG	Very early onset (<20 yrs), very rapid progression	Rarely reveals androgen excess in men
Baseline PSA	Before starting finasteride, age >40	Finasteride reduces PSA by ~50% — document baseline

Diagnoses not to miss

Diffuse loss without AGA pattern → check thyroid and ferritin. Patterned loss with perifollicular scale/erythema → consider lichen planopilaris. Rapid total loss in weeks → exclude autoimmune alopecia totalis. Patchy loss with scaling in a young man → tinea capitis not AGA.

Treatment of MAGA

Treatment aims to slow or halt progression and potentially achieve partial regrowth. The two licensed medical treatments — topical minoxidil and oral finasteride — have the strongest evidence base and can be initiated in primary care.

GP Analogy — Treatment Expectations

"Treating MAGA is like paddling upstream. If you paddle hard enough, you stop going backward and may make slight forward progress. If you stop paddling, you drift back — sometimes faster. Treatment is lifelong, stopping causes loss of all gains, and beginning early makes the paddling far easier."

Fig 5.4 — Treatment evidence and mechanism overview

Fig 5.4: The three main evidence-based treatment approaches. Combination therapy achieves superior outcomes to either agent alone and is now considered first-line for patients motivated to maximise hair preservation.

Minoxidil — prescribing guidance

Aspect	Topical minoxidil	Oral minoxidil (low-dose)
Dose	2% solution twice daily or 5% foam once daily	0.625–2.5 mg/day (off-label in most countries)
Evidence	Multiple RCTs; 5% superior to 2% in men	Growing evidence; may equal or exceed topical
Initial shedding	Common weeks 2–8; reassure — telogen effluvium	Same — reassure, do not stop
Side effects	Scalp irritation, contact dermatitis, facial hypertrichosis	Fluid retention (rare at low dose), body hypertrichosis
Stopping treatment	All gains lost within 3–4 months of cessation	Same — lifelong treatment required

Finasteride — prescribing guidance

Aspect	Detail
Dose	1 mg orally once daily (Propecia)
Contraindications	Women of childbearing potential (teratogenic — Category X), children
Sexual side effects	Decreased libido, erectile dysfunction, ejaculatory disorder — 1.8–3.8% in RCTs (vs 1.3% placebo). Majority resolve on cessation.
PSA effect	Reduces PSA by ~50% — document baseline before starting; double any PSA reading during treatment for prostate cancer screening
Depression	Label warning added 2012 — screen for depressive symptoms
Response	65–70% halt progression; 30–35% have visible regrowth; optimal at 2 years

Dutasteride, hair transplantation, and emerging therapies

Dutasteride

Dual 5-AR inhibitor

Inhibits both type I and type II 5-AR → reduces DHT by ~90% vs 70% with finasteride. Off-label in UK/Australia/USA. Evidence suggests superiority to finasteride.

Hair transplant (FUE)

Follicular unit extraction

Transplantation of DHT-resistant occipital follicles to bald zones. Best for stable, advanced loss (NW IV–VII). Always combine with medical therapy to protect non-transplanted hair.

Emerging therapies

PRP, LLLT, oral minoxidil

PRP (platelet-rich plasma): equivocal evidence. LLLT: modest RCT evidence, adjunctive role. Oral minoxidil: strong emerging evidence as a simpler alternative to topical.

Counselling key points

1. Treatment is lifelong — stopping loses all benefit within months. 2. Response takes 6–12 months — do not judge at 3 months. 3. Success = no further loss; regrowth is a bonus. 4. Combination therapy is more effective than monotherapy. 5. Adherence is the biggest predictor of outcome.

Quick recall — mnemonics

Pathophysiology: DART

D·A·R·T

DHT — the key androgen (5× potent)
AR — androgen receptor, overexpressed frontally
Reductase — 5-alpha type II converts T → DHT
Terminal → vellus miniaturisation cascade

Pattern: MTV

M·T·V

M — M-shaped bitemporal recession (early sign)
T — Top (vertex) thinning, circular
V — spared fringe at temporal/occipital V
Quiet scalp — no itch, no scale, no pain

Treatment: FILM

F·I·L·M

Finasteride — 1mg/day; blocks 5-AR type II
Information — lifelong, 6–12 mo response time
Low-dose oral minoxidil — emerging option
Minoxidil topical — 5% foam; prolongs anagen

Finasteride cautions: PDSP

P·D·S·P

PSA — halved; double readings for screening
Depression — label warning; screen
Sexual SE — libido, ED (reversible in most)
Pregnancy — absolute contraindication (teratogen)

GP quick-reference action card

Presentation	Diagnosis	First action	Treatment	Review
Man 20–50, M-shaped recession, FHx, no symptoms	MAGA types I–III	Confirm; counsel expectations	Minoxidil 5% foam ± finasteride 1mg	12 months — photograph baseline
Man 30–60, vertex + frontal loss, quiet scalp	MAGA types III–V	Dermoscopy; check for TE	Combination Mx + Fin; consider transplant referral	6–12 months
Man any age, diffuse loss without pattern	Exclude TE, thyroid, anaemia	FBC, ferritin, TFTs	Treat underlying cause first	3–6 months
MAGA + perifollicular scale, erythema	AGA + sebderm or LPP	Dermoscopy; if peripilar cast → refer	Treat sebderm (ketoconazole shampoo)	Urgent if scarring features
MAGA wanting hair transplant	Stable MAGA types IV–VII	Medical therapy first to stabilise	Refer transplant surgeon + maintain medical Rx	Post-transplant maintenance

Anki Flashcard Deck — Chapter 5

22 cards covering MAGA pathophysiology, classification, clinical features, diagnosis, and treatment. Tap to flip.

Card 1 / 22

tap card to flip

Deck complete

All 22 cards

References

APA 7th edition format.

1. Blumeyer, A., Tosti, A., Messenger, A., et al. (2011). Evidence-based (S3) guideline for the treatment of androgenetic alopecia in women and in men. Journal of the German Society of Dermatology, 9(Suppl 6), S1–S57. https://doi.org/10.1111/j.1610-0379.2011.07802.x
2. Cranwell, W., & Sinclair, R. (2016). Male androgenetic alopecia. In K. R. Feingold et al. (Eds.), Endotext. MDText.com. https://www.ncbi.nlm.nih.gov/books/NBK278957/
3. Ellis, J. A., Harrap, S. B., & Sinclair, R. (2001). The genetics of androgenetic alopecia. Clinics in Dermatology, 19(2), 149–154.
4. Garza, L. A., Liu, Y., Yang, Z., et al. (2012). Prostaglandin D2 inhibits hair growth and is elevated in bald scalp of men with androgenetic alopecia. Science Translational Medicine, 4(126), 126ra34. https://doi.org/10.1126/scitranslmed.3003122
5. Gubelin Harcha, W., Barboza Martínez, J., Tsai, T. F., et al. (2014). A randomized study of dutasteride versus finasteride in male subjects with androgenetic alopecia. Journal of the American Academy of Dermatology, 70(3), 489–498.e3.
6. Hamilton, J. B. (1951). Patterned loss of hair in man: Types and incidence. Annals of the New York Academy of Sciences, 53(3), 708–728.
7. Inui, S., & Itami, S. (2011). Androgen actions on the human hair follicle: Perspectives. Experimental Dermatology, 22(3), 168–171.
8. Kaufman, K. D., Olsen, E. A., Whiting, D., et al. (1998). Finasteride in the treatment of men with androgenetic alopecia. Journal of the American Academy of Dermatology, 39(4), 578–589.
9. Lolli, F., Pallotti, F., Rossi, A., et al. (2017). Androgenetic alopecia: A review. Endocrine, 57(1), 9–17. https://doi.org/10.1007/s12020-017-1280-y
10. Messenger, A. G., & Rundegren, J. (2004). Minoxidil: Mechanisms of action on hair growth. British Journal of Dermatology, 150(2), 186–194.
11. Norwood, O. T. (1975). Male pattern baldness: Classification and incidence. Southern Medical Journal, 68(11), 1359–1365.
12. Olsen, E. A., Dunlap, F. E., Funicella, T., et al. (2002). A randomized clinical trial of 5% topical minoxidil versus 2% topical minoxidil and placebo in men. Journal of the American Academy of Dermatology, 47(3), 377–385.
13. Tosti, A., Piraccini, B. M., & Soli, M. (2001). Evaluation of sexual function in subjects taking finasteride for androgenetic alopecia. Journal of the European Academy of Dermatology and Venereology, 15(5), 418–421.
14. Trüeb, R. M. (2002). Molecular mechanisms of androgenetic alopecia. Experimental Gerontology, 37(8–9), 981–990.
15. Wolff, H., Fischer, T. W., & Blume-Peytavi, U. (2016). The diagnosis and treatment of hair and scalp diseases. Deutsches Ärzteblatt International, 113(21), 377–386.