The Norwood Scale is an objective method of quantifying the degree of hair loss in an individual. It is mainly used to assess the severity and progression of male pattern baldness. The scale, also known as the Hamilton-Norwood scale, has seven grades. The scale was introduced by James Hamilton in the 50s, and modified by O’Tar Norwood in the 70s.
Because it is an objective scale rather than a subjective scale, the Norwood scale is important for documentation purposes when following up a patient suffering from progressive baldness. It also makes it easier to communicate about the condition with other healthcare providers in terms that provide all the needed information with clarity and without leaving out any important information. Using the Norwood Scale, hair loss is graded in the following manner:
Stage 1 of the Norwood scale refers to no recession of the hairline, or very minor recession. Usually individuals who are at this stage require no treatment since the problem is minor. This is particularly so if the individual does not have a family history of baldness. In case a person has Norwood Stage 1 hair loss and is seen by a professional, they would need to be closely monitored to assess the progression of the hair loss, and to decide when to institute treatment.
An individual is said to be in Norwood Stage 2 hair loss if they have triangular, symmetrical hairline recession at the frontal and temporal areas of the head (around the forehead and the temple). In this type of hair loss, the hair line usually remains a few centimeters in front of the hears. The central part of the scalp at the front may also have reduced hair density, and signs of early baldness are usually evident.
Individuals in stage 3 of the Norwood Scale typically manifest with hair loss that can be defined as baldness. They usually have deep hairline recession. Their temples are usually bare or covered with very sparse hair. The top of the head, called the vertex, usually has hair loss as well.
Stage 4 of the Norwood scale manifests as a recession of the temporal hairline that is more severe than in stage 3. In addition to that, there is typically a lack of hair on the top of the head. It is common to find a dense band of hair extending across the top of the head and separating the two areas of hair loss (at the crown and the temporal region)
In stage 5 of the Norwood Scale, the hair loss at the top of the head is still separated from the hair loss at the temples by a band of hair. However, the distinction is far less distinct, and the hair band is usually much thinner than in stage 4. It is also narrower and thinner. The remaining hair on the sides and back of the head form a horseshoe shape.
Stage 6 of the Norwood Scale manifests as very sparse hair between the top of the head and the temple. In addition to that, the hair loss on the sides is usually extended even further.
This is the last stage of the Norwood classification and represents terminal hair loss. This is the most advanced form of hair loss, and usually manifests as a very narrow band of hair in a horseshoe shape on the sides of the head and at the back of the scalp. The hair is usually very fine, and reduces with time.