Norwood Scale: Classifying male pattern baldness
The Norwood scale (also known as the Hamilton-Norwood scale) is the "gold standard" as a system of alopecia classification. It is used to measure the extent and pattern of male pattern baldness or androgenetic alopecia. Men typically lose their hair in one of many common patterns over several decades. The Norwood scale provides us with a simple reference image that indicates the different phases or stages of baldness.
There are many other scales to classify baldness used by doctors, researchers, and hair transplant specialists. Some rating scales include both sexes or focus on the female pattern of alopecia.
How many stages does the Norwood Scale have?
The Norwood scale, however, is the form of measurement most commonly used by clinicians for primarily academic purposes. It provides a benchmark for diagnosing the spread of baldness, discussing different treatment options, and measuring its effectiveness.
This scale consists of 7 stages, within which we can find various subdivisions that help us to exemplify in a simple way the evolution of baldness. Each of these stages or phases measure the progress and pattern of hair loss.
What are the 7 stages?
There is no significant hair loss or recession of the front line.
There is a slight recession of the front line around the storms. This is also known as an adult frontline or maturity frontline.
The first significant clinical signs of baldness become apparent. The front line presents a deep recession in the two periods, its image begins to appear with a shape like the letters M, U or V. The recession areas are seen completely empty or with few hairs throughout the area.
Stage 3 vertex.
The front line remains as in stage 2, but there is significant hair loss of hair in the upper area of the scalp or crown (vertex).
The recession of the frontal line is more severe than in stage 2, there is total hair loss or few hairs covering the vertex. The two areas of hair loss are separated by a hair band that connects the remaining hair on each side of the head.
The two areas of hair loss are wider than in stage 4. They are still separate but the band between them is narrower and the hair is less dense.
Temporary bald patches join alopecic patches at the vertex. The hair band across the top of the head is missing or there is too little hair density.
The most advanced stage of hair loss, only a band around the head is maintained with hair. Normally this is not observed with sufficient density or the hair appears very thin.
Norwood "class" A.
Class A is a variant of the Norwood scale, where a slight variation and a less common progression of hair loss are observed. The main differences are that the front line has a uniform recession, without maintaining an island of hair in the middle area, and there is no baldness in the vertex area. Instead, the front line progresses directly from the front to the back.