Classification of Baldness

There are two classification systems for baldness. Typical male pattern baldness, or androgenic alopecia, follows a fairly well defined pattern.Unfortunately, female baldness if more difficult to characterize though a system has been proposed and is most commonly used.

Hamilton Norwood Classification

Hamilton, an anatomist, recorded his observations of more than 300 men and graded their patterns of hair loss in 1949.  Dr. O’tar Norwood, a dermatologist and distinguished hair transplant surgeon, expanded Hamilton’s classification after conducting his own study of 1,000 men.  The Norwood classification, published in 1975, is the most widely used classification for hair loss in men. It defines two major patterns and several less common types.  As Norwood observed, thinning starts in both temples as well as the crown/vertex and slowly progresses to encompass the entire top of the scalp.This progression is noted in Norwood's classification which is depicted below.

Type I: No or very minimal hairline recession along the anterior border in the frontotemporal region.
Type II: The anterior border of the hair in the frontotemporal region has symmetrc triangular areas of recession which extend no further posteriorly than 2 cm anterior to a line drawn in a coronal plane at the level of the external auditory meatus.
Type III: The triangular areas in Type II extend posterior of the coronal plane which is 2 cm anterior to the external auditory meatus.  This is the minimal level considered to represent baldness.
Type III Vertex: Most of the hair loss is seen on the vertex.  Frontal hair loss may be similar to Types I or II but should not exceed Type III.  This type is most commonly seen with advancing age.
Type IV: Hair loss on the vertex associated with frontal loss more severe than Type III, but the frontal and vertex areas are separated by a distinct band of hair.
Type V: Greater hair loss than Type IV with only a sparse band of hair separating the frontal and vertex areas.  The hair left on the occipital and parietal areas begins to form the shape of a horseshoe when viewed from above (also true for Types VI and VII).
Type VI: The frontal and vertex areas of hair loss are contiguous with greater lateral and posterior areas of denudation.
Type VII: The most severe form of male pattern baldness. Only a narrow sparse horseshoe-shaped band of hair is left extending from the ears posteriorly to the occiput.

In addition, Types II through V can also be designated with a Type A variant.  The major features of the type A variant are: 1) the entire anterior hairline border recedes in unison without leaving the midfrontal peninsula of hair and 2) there is no simultaneous balding of the vertex.  The two minor features are 1) scattered sparse hairs frequently persisting in the entire area of balding and 2) the horseshoe shaped fringe of hair that remains on the sides and back tends to be wider and reaches higher on the head.  These variants exist only in about 3% of the population studies. 

Type IIA: The hairline is anterior to the coronal plane 2 cm anterior to the external auditory meatus.
Type IIIA: The hairline has receded back to a point between the limit of Type IIA and the level of the external auditory meatus.
Type IVA: The hairline has receded beyond the external auditory meatus but has not reached the vertex.
Type VA: The area of denudation includes the vertex. Hair loss more severe than Type VA cannot be distinguished from Types VI or VII.

Ludwig Classification of Female Hair Loss

The Ludwig classification is the most commonly used for female hair loss. There are three main classes each with increaseing hair loss.