In order to determine the best course of treatment for hair loss, it is important to understand the progression. The Norwood-Hamilton scale is the generally accepted standard to measure the extent of hair loss in men.

The most common type of male hair loss is called androgenetic alopecia, often referred to as “male pattern baldness” or “male pattern hair loss.” Male pattern hair loss is responsible for hair loss in about 90% of men. It can begin as early as the teens or twenties and is caused by a combination of genetic predisposition and male sex hormones.

There are several different patterns for male hair loss. The most common are a receding hairline beginning at the temples, thinning at the crown of the head (also called the vertex), and general thinning of the hair across large areas of the scalp without much direct change to the hairline. Men can experience one of these patterns of hair loss or a combination of all three.

The Norwood-Hamilton Scale outlines the different stages of male pattern hair loss. Vertex stages show hair loss at the crown of the head, while the “A” patterns demonstrate a more dramatic pattern of hair loss. Although this type of hair loss impacts less than 10% of men, it often appears more severe because hair loss is concentrated in the front of the head

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Stage I

Shows an adolescent hairline, generally located on the upper brow crease. There is no hair loss at the hairline or crown of the head.

Stage II

Demonstrates the progression to an adult hairline, which sits slightly above the upper brow crease. Hair loss at this stage is very mild and usually concentrated at the frontal hairline.

Stage III

This is the earliest stage of hair loss considered cosmetically significant enough to be called “baldness” according to this scale. At this stage, most men show a deep symmetrical recession at the temples, which are either bare or only sparsely covered with hair. The vertex figure here shows the additional thinning of the hair at the crown of the head.

Stage IV

Includes a deepening recession at the front of the head in the temple areas. Hair loss at the crown is evident and often a bridge of moderately dense hair will separate hair loss at the front of the scalp from that at the vertex or the crown of the head. The sides of the head are typically well-covered with hair.

Stage V

Marks the beginning of severe hair loss. While there remains a small separation between the loss of hair at the hairline and the loss of hair at the crown, the band of hair between the two is much thinner and narrower. Hair loss at both the crown and the temporal regions are larger and more distinct.

Stage VI

The bridge of hair that once separated the front of the head from the crown is now almost fully lost, only a few sparse strands may persist. The remaining hair now forms a horseshoe shape around the baldness concentrated in the center of the scalp. Hair loss on the sides of the head will also extend further at this stage.

Stage VII

The most advanced stage of hair loss, only a wreath of thin hair remains on the sides and back of the scalp.


According to a study, less than 45% of women will maintain a full head of hair throughout their lifetime. While there are various causes of female hair loss, the most common is androgenetic alopecia or female pattern hair loss. Similar to male pattern hair loss, both heredity and hormones seem to play major roles in female pattern hair loss. However, patterns of hair loss appear differently in women than in men. Whereas male pattern hair loss typically concentrates at the front of the hairline and at the crown of the head, women with androgenetic alopecia more often have diffuse thinning on all areas of the scalp.

Once the cause of the hair loss is determined, the next step in figuring out the best course of treatment is to evaluate the extent of the hair loss. Several scales measure the extent of female hair loss, but the two most common standards are the Ludwig Scale and the Savin Scale. The two are almost identical, except the Savin Scale measures overall thinning as well as the density in the hair, shown by the hair pictured at the crown.

Stages I-1, I-2, I-3, I-4:

illustrate the female crown hair density. The first stage (I-1) shows a woman with a central part in her hair with no hair loss. The part widens in images I-2, I-3, and I-4, demonstrating thinning hair along the top of the scalp and the crown area.

Stages II-1, II-2:

Show increasingly thin hair at the top of the scalp as the hair loss advances.

Stage III

Represents a woman with severe female pattern hair loss, concentrated at the top of the head and crown area.


While rarely seen in clinical practice, this picture shows a very advanced stage of female pattern hair loss, with almost no hair remaining on the crown or top of the head


Demonstrates female pattern hair loss concentrated more at the forehead area than the crown of the head and gradually moves back. This pattern is fairly rare among women who experience hair loss.