Alopecia areata does not follow the Norwood scale because it is an entirely different condition from the androgenetic alopecia (pattern hair loss) that the Norwood system was designed to classify. Misdiagnosis of hair loss type leads to wrong treatment in about 28% of cases, and confusing these two conditions is one of the most common errors. Understanding why these classification systems differ helps you get the right diagnosis and the right treatment.
This article is for informational purposes only and does not constitute medical advice.
What the Norwood Scale Actually Measures
The Norwood-Hamilton scale classifies male pattern hair loss into seven stages based on a predictable progression of hair loss driven by dihydrotestosterone (DHT). Each stage follows a recognizable pattern:
| Norwood Stage | Pattern | Typical Grafts Needed |
|---|---|---|
| Norwood 1 | No significant hair loss | 0 (preventive care only) |
| Norwood 2 | Slight recession at temples | 800 to 1,500 |
| Norwood 3 | Deep temple recession forming M-shape | 1,500 to 2,200 |
| Norwood 3V | Temple recession with vertex thinning | 2,000 to 2,800 |
| Norwood 4 | Further recession with enlarged vertex area | 2,500 to 3,500 |
| Norwood 5 | Narrowing separation between front and vertex | 3,000 to 4,500 |
| Norwood 6 | Bridge between areas lost, horseshoe pattern | 4,000 to 6,000 |
| Norwood 7 | Most extensive loss, narrow band remains | 5,500 to 7,500 |
The key feature of the Norwood scale is predictability. Hair loss starts at the temples and vertex and expands in a known direction over years or decades. Surgeons use these stages to plan graft counts, estimate donor requirements, and set realistic expectations for transplant outcomes.
Why Alopecia Areata Cannot Be Norwood-Classified
Alopecia areata behaves in fundamentally different ways from pattern hair loss:
Unpredictable Location
Alopecia areata can appear anywhere on the scalp (or body), at any time. A patch might form at the occipital region, the crown, the temporal area, or the frontal hairline with no predictable sequence. This randomness makes stage-based classification meaningless because there is no progression pathway to follow.
Non-Linear Progression
Pattern hair loss moves in one direction: forward. It gets progressively worse over time without treatment. Alopecia areata can expand, stabilize, resolve spontaneously, and then recur in a completely different location. Some patients have a single episode that resolves within a year. Others experience chronic relapsing disease. There is no orderly staging system that captures this variability.
Different Mechanism
The Norwood scale tracks DHT-driven follicle miniaturization, a hormonal process where hair gradually becomes finer and shorter over many growth cycles until follicles produce only invisible vellus hairs. Alopecia areata causes sudden shutdown of otherwise healthy follicles through immune attack. The follicles do not miniaturize; they simply stop producing hair abruptly.
Reversibility
Norwood progression is largely permanent without treatment. Once follicles have fully miniaturized at advanced stages, they do not spontaneously recover. Alopecia areata, by contrast, preserves the follicle structure, and complete spontaneous regrowth occurs in 50% of cases with limited disease within one year, even without treatment.
How Alopecia Areata Is Actually Classified
Instead of the Norwood scale, alopecia areata uses its own classification based on extent and pattern:
By Extent
- Patchy alopecia areata: One or more round patches of hair loss, the most common form
- Alopecia totalis: Complete loss of all scalp hair
- Alopecia universalis: Complete loss of all body hair, including scalp, eyebrows, eyelashes, and body hair
By Pattern
- Patchy: Distinct round or oval patches
- Ophiasis: Band-like loss along the temporal and occipital margins of the scalp (treatment-resistant pattern)
- Sisaipho (reverse ophiasis): Hair loss in the central scalp with retention at the margins
- Diffuse: Widespread thinning across the scalp without distinct patches (hardest to diagnose, often confused with telogen effluvium or early pattern hair loss)
By Severity Score (SALT)
The Severity of Alopecia Tool (SALT) score provides a numerical assessment of scalp hair loss from 0 (no loss) to 100 (complete loss). This is the standardized measure used in clinical trials, particularly for JAK inhibitor studies where 35 to 40% of severe patients achieved major regrowth.
When Both Conditions Coexist
It is possible to have both alopecia areata and androgenetic alopecia simultaneously. In these cases, you may see Norwood-pattern thinning at the temples and crown alongside distinct smooth patches characteristic of alopecia areata. This dual diagnosis complicates treatment because each condition requires a different approach.
For the pattern component:
- Finasteride: 80 to 90% halt further loss, 65% experience regrowth
- Minoxidil: 40 to 60% regrowth rate
- These work on DHT and blood flow but do not address the autoimmune component
For the alopecia areata component:
- Corticosteroid injections: 60 to 70% response for limited patches
- JAK inhibitors for severe cases
- These target the immune system but do not prevent DHT-driven miniaturization
A dermatologist can identify which areas are affected by which condition using dermoscopy, which reveals miniaturized hairs (pattern loss) versus exclamation point hairs and yellow dots (alopecia areata).
Why This Distinction Matters for Transplant Planning
When a patient eventually qualifies for hair transplantation, knowing whether their loss is Norwood-pattern, alopecia areata, or both determines everything about the surgical plan.
For Norwood-pattern loss, surgeons can predict future loss based on the stage and plan graft placement accordingly. A Norwood 4 patient needs 2,500 to 3,500 grafts. The donor area (back and sides of the scalp) is predictably safe because DHT-resistant follicles grow there permanently. Safe extraction is limited to 45% of the donor area, with each graft containing an average of 2.2 hairs.
For alopecia areata, none of these calculations are reliable during active disease. The donor area is not guaranteed to remain safe because the immune system can attack any follicle, including transplanted ones. This is why the two to three year remission requirement exists. Understand more about alopecia areata causes and check whether you meet the criteria through the hair transplant candidacy assessment.
Getting the Right Classification
If you are unsure whether your hair loss follows a Norwood pattern or an alopecia areata pattern, a dermatologist using dermoscopy can differentiate within minutes. Getting this classification right is the first step toward the correct treatment. Do not assume your hair loss type based on family history alone, as the 28% misdiagnosis rate demonstrates how often this goes wrong even among professionals.
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