The Norwood scale has been popularly used for the classification of male pattern baldness from stages I- VIII. Although first developed by Dr James Hamilton, it was later modified by Dr Norwood in his study “Male Pattern Baldness Classification Incidence” in 1975.
It is this scale that’s commonly used by medical practitioners, including dermatologists and hair transplant surgeons. Due to the contributions of two different surgeons, it’s also known as the Norwood-Hamilton scale.
What Is The Hamilton-Norwood Scale?
It was James Hamilton who first noted that the presence of male sex hormones contributed to the development of male pattern baldness. Although hair loss can worsen in individuals who have higher levels of these hormones, it’s not always necessary to trigger this kind of alopecia. Even at normal levels, the sensitivity of hair follicles to DHT makes them susceptible to miniaturization and eventual shedding. That is because of the genetics of an individual.
With the help of this scale, clinicians can determine the severity of hair loss in a patient. Specifically, it helps in the identification of hair loss due to androgenetic alopecia that’s because it usually follows a fixed pattern. The different stages of this scale show the procession of that pattern of hair loss.
It starts with the formation of an “M” along the hairline, which becomes more and more pronounced before it takes on a “U” shape due to the recession of the entire hairline. Meanwhile, thinning occurs along the crown/vertex region. Both the crown hair loss and hairline recession meet at the top of the head, leaving the entire area bald.
According to the International Society of Hair Restoration Surgery (ISHRS), it’s estimated that people in their 20s have no more than a 20% chance of getting pattern baldness, people in their 30s have a 30% chance and so on and so forth. However, it is noted that for a person who’s in his 20s, predicting the pattern of hair loss can be quite difficult. In fact, there’s no way of knowing it exactly, even as the person continues to lose their hair.
Link Between Norwood Scale & Health Conditions
Although, of course, there’s no direct relationship between the Norwood scale and any health conditions, this scale has been useful in predicting the risks of certain diseases.
According to the Prostate Cancer Foundation, people higher up on the Norwood scale are three times as likely to end up with prostate cancer that needs to be treated. Another study published in the International Journal of Trichology found that males with androgenetic alopecia were also at a higher risk of developing cardiovascular diseases. Again, the relationship was independent, one factor didn’t affect the other. However, still, how these conditions are linked is yet to be studied.
What Are the Stages of the Hamilton-Norwood Scale of Male Pattern Baldness?
There are 7 stages listed on the Norwood hair scale, 8 including Stage 3 Vertex, with a further ‘A’ classification for those with a slightly different pattern of hair loss. Keep in mind that the progression of hair loss from one stage to another can take years. The stages manifest as follows:
Stage 1 – It is the point at which most healthy-haired individuals will be. This stage features no significant hair loss beyond the norm and no recession of the overall hairline.
Stage 2 – It is characterised by a slight recession of the hairline, typically starting at the temples.
Stage 3 – This is when the balding starts to take the pattern that’s most commonly seen in patients with androgenetic alopecia. Seen from above, the hairline forms an “M” shape.
Stage 3 Vertex – When the hair begins to thin or bald at the crown (or vertex) of the head, this is known as ‘Stage 3 Vertex’. This is less severe than ‘Stage 3.’ A person can experience both these stages at once or just one of them.
Stage 4 – Compared to stages 2 and 3, stage 4 features further loss of hair across both the temples and the vertex. This can be split up by a band of hair remaining between the two balding regions. The hooks of “M” have started to take more of a “U” shape along the hairline.
Stage 5 – The band separating the hair loss becomes narrower and sparse. This stage is marked by more severe hair loss and further progression of it.
Stage 6 – The balding areas on the temples will join at this stage, leaving very thin hair left across the band or none at all.
Stage 7 – This is the most severe stage of hair loss and will manifest in no hair on the top of the head and only a band of hair around the sides and back of the head. The remaining hair in the balding areas will be very thin and weak. These, too, will eventually fall away.
The A-Classification
This is a type of pattern of hair loss that some people experience instead of the one mentioned above. The main difference between the two is that in this, it’s only the hairline that will continue to recede, so much so that it will end up enveloping the crown region. Its stages can be seen as:
Stage 2A – The hairline has the classic “M” shape. There are no other thinning, balding areas on the scalp.
Stage 3A – The “M” of the hairline is further diminished to form a “U” shape.
Stage 4A – The hairline continues to recede as hair loss becomes more severe.
Stage 5A – The hairline recedes all the way back to the crown.
How Is The Norwood-Hamilton Hair Loss Scale Used In Hair Transplant?
If you’re getting a hair transplant surgery, the number of hair grafts you need to cover the balding areas will be determined using this Norwood Scale. You can find this out for yourself using a graft calculator. This can determine the kind of hair transplant technique that’ll best meet your needs and expectations. That’s why understanding this scale is important.
If using this scale, it is determined that you need more than 4,500 hair grafts (because hair loss is occurring from zone 1-7) then you’d need to have more than one hair transplant session. This will be discussed with you in the preparation of your treatment plan.
While there’s no way to reverse any Norwood stage, you can get it treated through a hair transplant, where your hair will grow just like your existing, natural hair. In addition, you can be on one stage for quite a while and stay on that one. In this case, you don’t have to wait for the hair loss to progress to stage 7 or 8 before getting treatment. You can get it at any stage from 2-8.
Is The Norwood Scale Reliable?
There have been concerns regarding the reliability of the Norwood scale. That’s because not always do people come to the same conclusions when viewing this scale for determining their hair loss. However, the Norwood scale is simply a tool that helps in the diagnosis of hair loss. If you’re suffering from androgenetic alopecia, the doctor might perform different hair tests.
In addition to physically examining the scalp, they’ll also ask you about your family history (since genetics are significant when it comes to pattern baldness). To rule out other hair conditions, they may also have a blood test done in addition to other tests.
Is There A Norwood Hair Scale Equivalent For Females?
There are two different types of scales by hair specialists:
Ludwig Scale
For the diagnosis of the female pattern baldness and the measuring of its severity, the Ludwig scale is used. It was first presented in 1977 in a study titled “Classification of the types of androgenetic alopecia (common baldness) occurring in the female sex” by Dr E. Ludwig. It has three stages.
Stage 1 – Thinning along the part line of the scalp and the crown. It doesn’t affect the hairline.
Stage 2 – Severe loss of hair in the crown region and top of the head. At this stage, the skin of the scalp starts showing through quite clearly.
Stage 3 – There is a complete loss of hair in the crown and front regions of the scalp. The frontal fringe might persist.
Even though this classification system is used for the diagnosis and progression of female hair loss, women can lose their hair in the same pattern as male androgenetic alopecia. Moreover, this scale may not be applicable if the woman is experiencing diffuse hair loss (affecting the whole scalp).
Savin Scale
In 1994, the Savin scale divided hair loss into 8 stages. It has further subcategorization for frontal hair loss:
Stage I-1 – The central parting of the scalp shows no hair loss.
Stage I-2 – There is a slight widening of the gap.
Stage I-3 – The part continues to widen, with the scalp starting to show through.
Stage I-4 – The part further widens.
Stage II-1 – More significant widening of the part line.
Stage II-2 – Hair loss continues, hair pulling back on the sides.
Stage III – There is a significantly large bald patch extending to the crown region.
Advanced – As the name indicates, it is the “advanced” stage of hair loss. Here, the frontal fringe has also started to thin.
Frontal – The hairline starts to undergo recession.
Concluding Remarks
Norwood scale is a classification of the severity of male pattern baldness. It has 8 stages that show the progression of the loss of hair in the form of a set pattern. This is helpful for surgeons in the diagnosis of the condition. However, it has its limitations, so other tests may also be performed. In any case, you can use it to get an estimate of the total number of hair grafts that you’d need when getting a transplant surgery.
Reviewed and Approved by Dr. Hassan Soueid.
