What Does the Hamilton-Norwood Scale Tell Us About Hair Loss?

What Hamilton Norwood Scale Explains

The Hamilton-Norwood Scale (HNS) is widely used in clinical practice to evaluate the severity and progression of androgenetic alopecia (AGA).

Hamilton, an anatomist, conducted a clinical study involving over 300 men with hair loss and introduced a comprehensive classification system to describe the pattern and progression of androgenetic alopecia. Hamilton grouped the classifications into two main categories: (a) non-balding scalps (Types I–III) and (b) balding scalps (Types IV–VIII), each representing distinct patterns of hair loss severity1.

Stages in HNS

Type I: A variant of this pattern may present with a uniformly high anterior hairline across the forehead, without localized thinning or temple recession.

Type II: The anterior hairline shows triangular recessions in the frontoparietal regions, characteristic of early pattern hair loss. Additionally, there is thinning or sparsity of hair along the midfrontal scalp, although the extent of recession in this area is less pronounced than in the temples.

Type III: This stage includes scalps where accurate classification is challenging due to factors such as scarring, asymmetrical patterns of hair loss, or atypical forms of hair thinning and sparseness.

Type IV: It represents the earliest degree of hair loss that qualifies as true baldness. It is characterized by deep, typically symmetrical frontotemporal recessions that may be either bare or covered with only sparse hair. In some cases, there may also be a broad band of thinning or absent hair along the entire anterior hairline.

Type V: This stage involves significant recession in the frontoparietal and frontal regions, accompanied by noticeable thinning or complete loss of hair at the crown.

Type VI: In this pattern, the tonsural area of hair loss is separated from the more anteriorly located balding regions by a narrow, laterally extending strip of scalp with only mild thinning. An isolated patch of hair remains along the midline just in front of this lateral bridge. In some variants, the mid-frontal hair may be noticeably sparse or completely absent.

Type VII & VIII: In these stages, the horseshoe-shaped area of thinning or baldness is continuous, without any laterally directed strip of well-preserved hair. This pattern results from the merging and expansion of the occipital (tonsural) and anterior balding regions.

Insights from a Hair Transplant Surgeon: Understanding Your Hair Loss Stage

To understand the progression of male pattern baldness, the HNS remains an essential tool in clinical practice. Whether you are considering medical therapy or surgical restoration, knowing your specific stage helps guide the best approach for lasting results. We are here to assist, both in-person at our clinic and via video consultation.

References:

1-Gupta M, Mysore V. Classifications of Patterned Hair Loss: A Review. J Cutan Aesthet Surg. 2016;9(1):3-12. doi:10.4103/0974-2077.178536