Male androgenetic alopecia (AGA) progresses from the hairline and crown in defined zones, while female pattern hair loss (FPHL) produces diffuse thinning concentrated along the part line. These fundamentally different patterns require completely different photo protocols, measurement zones, and benchmarks. Using the wrong protocol leads to systematic measurement errors that can mask real changes or flag false positives.
The Core Pattern Difference
Understanding why male and female hair loss behave differently starts with the underlying biology.
Male Androgenetic Alopecia
DHT (dihydrotestosterone) attacks follicles in genetically sensitive zones: the frontal hairline, temples, and vertex (crown). The result is a pattern of recession and balding that follows the Norwood scale from stage 1 (no significant loss) to stage 7 (most extensive loss with only a narrow band remaining).
The donor area (back and sides of the scalp) is typically resistant to DHT, which is why it serves as the source for hair transplants.
Female Pattern Hair Loss
FPHL involves diffuse thinning across the top of the scalp, with particular density loss along the natural part line. The frontal hairline is usually preserved, which is why many women do not notice the loss until it reaches moderate severity (Ludwig II).
The hormonal mechanism in FPHL is more complex than in male AGA. While DHT plays a role, aromatase activity, estrogen levels, and androgen receptor sensitivity all contribute. This is why finasteride (which targets only DHT) is less consistently effective in women than in men.
Photo Protocol Differences
The single biggest tracking error is using male photo angles for female tracking or vice versa.
Male Protocol: Three Essential Angles
| Photo | Camera Position | Target Zone | Purpose |
|---|---|---|---|
| Frontal hairline | Eye level, facing forward | Temples and frontal line | Recession measurement |
| Profile (both sides) | Eye level, 90 degrees from center | Temple points | Temple recession depth |
| Vertex | Directly overhead | Crown | Vertex density and expansion |
Male tracking requires precise frontal hairline documentation because recession is the primary indicator of progression. The camera must be at eye level, not above, to accurately capture the hairline contour. A downward angle underestimates recession because it compresses the forehead.
Female Protocol: Two Essential Angles
| Photo | Camera Position | Target Zone | Purpose |
|---|---|---|---|
| Top-down part line | Directly above the head | Part line from front to back | Part width and density |
| 45-degree crown | Behind and above, angled down | Crown-to-vertex area | Diffuse thinning assessment |
Female tracking requires a top-down view because the part line widening is the primary indicator of progression. The camera must be directly overhead to capture the part symmetrically. A tilted angle creates uneven lighting across the part, which produces asymmetric density readings.
Why Mixing Protocols Causes Errors
If a woman uses the male frontal hairline protocol, the tracking system monitors a zone where FPHL produces minimal change. The result: the system reports "stable" while actual density loss continues at the part line and crown.
If a man uses the female top-down protocol, the tracking system monitors the part line, which is not where male AGA manifests (except in diffuse patterned alopecia, which affects about 10% of men). The result: the system reports "stable" while actual recession continues at the temples.
Measurement Zone Differences
The zones where density is measured must match the loss pattern being tracked.
Male Measurement Zones
| Zone | Norwood Relevance | Measurement Priority |
|---|---|---|
| Frontal hairline (midline) | All stages | Primary |
| Left temple point | N2+ | Primary |
| Right temple point | N2+ | Primary |
| Vertex center | N3V+ | Secondary (becomes primary at N3V+) |
| Midscalp bridge | N5+ | Tertiary |
| Donor area (occipital) | Transplant planning | Baseline reference |
For a Norwood 2 patient (800-1,500 grafts typical), the frontal and temple zones are the active tracking areas. For Norwood 4+ (2,500-3,500+ grafts typical), the vertex zone becomes equally important.
Female Measurement Zones
| Zone | Ludwig Relevance | Measurement Priority |
|---|---|---|
| Part line center | All stages | Primary |
| Part line anterior | Ludwig I detection | Primary |
| Part line posterior | Christmas tree pattern | Primary |
| Crown center | Ludwig II+ | Secondary |
| Temporal zones | Rules out AGA overlap | Tertiary |
| Frontal hairline | Confirms FPHL pattern | Baseline reference |
For a Ludwig I patient (10-20% density loss), the part line zones capture the earliest changes. The frontal hairline is measured not for tracking progression but for confirming the diagnosis: preserved frontal hairline points toward FPHL rather than male-pattern AGA.
Benchmark Population Differences
Comparing your density to the right reference population is essential for meaningful tracking.
Baseline Density by Ethnicity and Sex
| Ethnicity | Male Average (FU/cm2) | Female Average (FU/cm2) |
|---|---|---|
| Caucasian | 200 | 200 |
| Asian | 170 | 170 |
| African | 150 | 150 |
| Hispanic | 170 | 170 |
| Middle Eastern | 180 | 180 |
Baseline density does not differ significantly between men and women of the same ethnicity. The difference is in the pattern of loss, not the starting density. However, the rate of loss and the treatment response benchmarks differ substantially.
Treatment Response Benchmarks by Sex
| Treatment | Male Response | Female Response |
|---|---|---|
| Finasteride 1mg | 80-90% halt, 65% regrowth | Less consistent, off-label use, lower response rate |
| Minoxidil 5% | 40-60% moderate regrowth | 40-60% moderate regrowth (FDA approved for women at 2%) |
| Dutasteride 0.5mg | More effective than finasteride, off-label | Rarely used in women, hormonal concerns |
| Spironolactone | Not typically used in men | First-line anti-androgen for FPHL |
| PRP ($500-$2,000/session) | 30-40% density increase | 30-40% density increase |
The most significant difference is in anti-androgen therapy. Finasteride is the first-line treatment for male AGA but is contraindicated in pregnant women and less consistently effective in postmenopausal women. Spironolactone is the first-line anti-androgen for women but is not used in men due to feminizing side effects.
Rate of Progression Differences
Male and female hair loss progress at different speeds, which affects how often you should track.
Male AGA Progression
Without treatment, male AGA typically progresses one Norwood stage every 3-5 years after onset. The rate is fastest in the 20s and 30s, slowing in the 40s and 50s. Some men progress rapidly (N2 to N5 in 5 years), while others progress slowly (N2 to N3 over 15 years).
Recommended tracking frequency for men: every 4-6 weeks during active treatment, every 8-12 weeks during maintenance.
FPHL Progression
Female pattern hair loss progresses more slowly and more variably than male AGA. Many women remain at Ludwig I for decades, while others progress from I to II within 2-3 years. Hormonal events (pregnancy, menopause, PCOS diagnosis) can accelerate progression.
Recommended tracking frequency for women: every 4-6 weeks during active treatment, every 6-8 weeks during hormonal transitions, every 8-12 weeks during stable periods.
The Overlap Cases
About 10-15% of hair loss presentations do not fit neatly into male or female categories.
Diffuse Patterned Alopecia (DPA) in Men
DPA affects the entire top of the scalp rather than following the classic Norwood recession pattern. Men with DPA show thinning that looks similar to female FPHL. For tracking purposes, these men benefit from the female top-down photo protocol rather than the male frontal protocol.
Female AGA Pattern
About 5% of women develop frontal recession that resembles male-pattern AGA. This is often associated with hyperandrogenism (elevated androgen levels) from conditions like PCOS. These women benefit from the male tracking protocol, including frontal hairline documentation.
How myhairline.ai Handles Overlap
The app allows pattern-based tracking that overrides the default gender protocol. If you are a man with diffuse thinning, you can select "diffuse crown" as your pattern type, which activates the top-down photo protocol and Ludwig-based benchmarks. If you are a woman with frontal recession, you can select "frontal recession" for Norwood-based monitoring.
Practical Setup Recommendations
For Men
- Select male profile in myhairline.ai
- Set your current Norwood stage (N2 at 800-1,500 grafts through N7 at 5,500-7,500 grafts)
- Use the frontal, profile, and vertex photo prompts
- Track every 4-6 weeks
- Benchmark against male AGA treatment response curves
For Women
- Select female profile in myhairline.ai
- Set your current Ludwig stage (I through III)
- Use the top-down and 45-degree crown photo prompts
- Track every 4-6 weeks during treatment, more frequently during hormonal transitions
- Benchmark against FPHL treatment response curves
For Non-Binary or Uncertain Pattern
- Select condition-based profile
- Choose your actual loss pattern (frontal, diffuse, vertex, or combination)
- The app will assign the appropriate photo protocol automatically
- Benchmarks are drawn from users with the same loss pattern, regardless of gender
Start tracking with the protocol matched to your specific loss pattern at myhairline.ai/analyze for the most accurate benchmarks and progress monitoring.
This article is for informational purposes only and does not constitute medical advice. Consult a board-certified dermatologist for personalized hair loss diagnosis and treatment recommendations.