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Year : 2016  |  Volume : 9  |  Issue : 3  |  Page : 192-195
Ahmad's NPRT system: A practical innovation for documenting male pattern baldness

Plastic and Hair Restorative Surgeon, Hair Transplant Institute, Islamabad, Pakistan

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Date of Web Publication7-Oct-2016


Various classifications for male pattern baldness are mentioned in the literature. The 'Norwood's classification is the most commonly used but it has certain limitations. The new system has included 'three' extra features which were not mentioned in any other classification. It provides an opportunity to document the full and correct picture while documenting male pattern baldness. It also aids in assessing the treatment for various degrees of baldness.

Keywords: Hair loss classification, hair loss, male androgenic alopecia, Norwood scale

How to cite this article:
Ahmad M. Ahmad's NPRT system: A practical innovation for documenting male pattern baldness. J Cutan Aesthet Surg 2016;9:192-5

How to cite this URL:
Ahmad M. Ahmad's NPRT system: A practical innovation for documenting male pattern baldness. J Cutan Aesthet Surg [serial online] 2016 [cited 2022 Oct 7];9:192-5. Available from:

   Introduction Top

More than 50% of the men experience some degree of hair loss in their lives.[1] With increase in the population, the total number of men with baldness will keep on increasing. The increase in the male population has resulted in changes in male hair loss patterns (e.g., the total population of men in 2015 is more than the total population of men and women in 1950).[2] There have been a few classifications for male pattern hair loss described in the literature. The first attempt was made in 1950 by Beek in male White patients and in 1951 by Hamilton in White and Chinese population.[3],[4] The most commonly used is Hamilton–Norwood classification presented in 1974.[5] The change in the patterns may be due to environmental changes, climate changes, racial changes, dietary factors, etc.[6] As noted by Hamilton, the basis of male pattern baldness is the hormonal factor along with the genetic pre-disposition and age.[7] Because of the isolation of genes responsible for male pattern hair loss, there may be redistribution/mix-up of the genetic materials from different races as a process of evolution, which can result in a change in the expression of these genes.

The Norwood classification is considered to be 'gold standard' for categorising male pattern hair loss. There have been certain other classifications due to the versatility of baldness patterns.[8],[9],[10] With an experience of over a decade, the author has attempted to develop a system for documenting the features of male pattern baldness, improving the 'gold standard' and adding certain details to the points not mentioned earlier in Norwood's classification.

   Proposed Classification Top

The new classification comprises four points.

Norwood classification

The Norwood grades serve the main part of the classification, and the types remain as I–VII and variants as IIIa, IIIv and IVv [Figure 1].
Figure 1: Norwood–Hamilton classification (adopted from Norwood OT. Male pattern baldness; classification and incidence. Southern Med J 1975;68 (11):1359-65)

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Temporal peaks/points

Denoted by the letter 'P', the different grades are being proposed from '0' to '3' with the letter 'P' [Figure 2].
Figure 2: Temporal points/peaks (P)

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  • P0 indicates 'no' hair loss at the temporal points
  • P1 indicates the temporal point (apex of the peak) is located not less than the junction of one-third and two-third of the distance between the outer canthus to tragus
  • P2 denotes that the temporal point is located not less than the half of the distance between the outer canthus to tragus
  • P3 denotes the reverse of P1 i.e., the temporal point is located at the distance <two-third and one-third between the outer canthus to tragus.

Reverse thinning

It is denoted by the letter 'R'. It is the hair loss in the occipital area and above the ears (mastoid area), which may be combined with loss of peaks [Figure 3]. The following grades are proposed. 'Reverse thinning' means more skin is visible than hair.
Figure 3: Reverse thinning (R)

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  • R0 denoted 'no' reverse thinning
  • R1 indicates 'mild reverse thinning' i.e., the density is decreased considerably and is limited only to 1 cm above ears and/or occipital area
  • R2 indicates 'moderate reverse thinning' i.e., the hair loss/decreased density is more than 1 cm, but <2 cm
  • R3 indicates 'severe reverse thinning' and involves the decrease in density/hair loss more than 2 cm above the ears and/or above the line joining both ear lobes.

Overall thinning

It is denoted by the letter 'T' [Figure 4].
Figure 4: Overall thinning (T)

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  • T0 indicates 'no' thinning
  • T1 indicates the 'mild' loss in density (<25%) i.e., more skin is visible than hair
  • T2 indicates the 'moderate' loss in density (more than 25% but <50%) i.e., much skin is visible than hair
  • T3 indicates 'severe' loss of density (more than 50%) i.e., too much skin is visible than hair.

The density can be measured at the level of external occipital protuberance. The density of 100 hair/cm 2 is taken normal.

After the Hamilton–Norwood classification, a few limitations were observed, for example, it puts more emphasis only on vertex classification, the temporal regression is not discussed. To address the limitations, a few other classifications have been developed.[8],[9],[10],[11],[12] Bouhanna developed a multifactorial classification.[13] These classifications were based on the study of Caucasians of different ages. The basic and specific pattern (BASP) classification was developed by Lee et al. in Asian population in 2007.[10] The BASP classification has various points which are difficult to memorise. In spite of the claim, it is more complicated and has limitations too. It has not been able to get a worldwide acceptance mainly due to its complexity of the description of various points. It lacks the descriptions which are required for the physicians, and it does not encompass the versatility of different patterns. It also has limitations that certain points are confused with Norwood scale.[14] Similarly, temporal points have also been classified by Brandy and Mayer and Perez-Meza, but these have not been able to get incorporated in the Norwood scale.[15],[16] The various differences in the hair loss pattern, not relating to a specific pattern in Norwood scale, are termed 'non-specific' patterns and these non-specific patterns need a classification system.

The classification system presented addresses all the lacking issues in the previous classifications. It seems to be less complicated and can be easily memorised. It maintains the 'gold standard' to which various points are added. The Norwood scale is mentioned, and these three points are expressed in bracket, for example, Type VI (P1, T2 and R2) or VI (P2, T0 and R0), etc.

The current system has the advantage of combining and documenting various assessment points at the same time and can predict the future loss in baldness. It also helps in planning the surgical procedure as well. The author has been using this current method for more than a year after developing it. It was found to be very useful, especially when the patients with Norwood Type VI or VII and having advanced thinning (T3 or R3) visit the clinic for hair restoration, which are difficult to be documented.

   Conclusion Top

The current system is easy and needs further studies to improve on the standard classification for male pattern baldness.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.

   References Top

Unger WP, Shapiro R. editors. Hair Transplantation. 4th ed. New York: Marcel Dekker Inc.; 2004.  Back to cited text no. 1
United States Consensus Beaurou. Available from: [Last accessed on 2016 Feb 01].  Back to cited text no. 2
Beek CH. A study on extension and distribution of the human body-hair. Dermatologica 1950;101:317-31.  Back to cited text no. 3
Hamilton JB. Patterned loss of hair in man; types and incidence. Ann N Y Acad Sci 1951;53:708-28.  Back to cited text no. 4
Norwood OT. Male pattern baldness: Classification and incidence. South Med J 1975;68:1359-65.  Back to cited text no. 5
Bas Y, Seckin HY, Kalkan G, Takci Z, Citil R, Önder Y, et al. Prevalence and types of androgenetic alopecia in North Anatolian population: A community-based study. J Pak Med Assoc 2015;65:806-9.  Back to cited text no. 6
Hamilton JB. Male hormone stimulation is prerequisite and an incitant in common baldness. Am J Anat 1942;71:451-80.  Back to cited text no. 7
Savin RC. Evaluating androgenetic alopecia in male and female patients. Kalamazoo, MI: The Upjohn Company; 1994.  Back to cited text no. 8
Cohen BH. The hair loss profile and index. J Cosmet Dermatol 2002;15:19-23.  Back to cited text no. 9
Lee WS, Ro BI, Hong SP, Bak H, Sim WY, Kim do W, et al. A new classification of pattern hair loss that is universal for men and women: Basic and specific (BASP) classification. J Am Acad Dermatol 2007;57:37-46.  Back to cited text no. 10
Kim JY, Kim MH, Hong SP, Park BC. Characteristics of nonbalding scalp zones of androgenetic alopecia in East Asians. Clin Exp Dermatol 2015;40:279-85.  Back to cited text no. 11
Hong H, Ji JH, Lee Y, Kang H, Choi GS, Lee WS. Reliability of the pattern hair loss classifications: A comparison of the basic and specific and Norwood-Hamilton classifications. J Dermatol 2013;40:102-6.  Back to cited text no. 12
Bouhanna P. Multifactorial classification of male and female androgenetic alopecia. Dermatol Surg 2000;26:555-61.  Back to cited text no. 13
Agarwal S, Godse K, Mahajan A, Patil S, Nadkarni N. Application of the basic and specific classification on patterned hair loss in Indians. Int J Trichology 2013;5:126-31.  Back to cited text no. 14
Brandy DA. A method for evaluating and treating the temporal peak region in patients with male pattern baldness. Dermatol Surg 2002;28:394-400.  Back to cited text no. 15
Mayer ML, Perez-Meza D. Temporal points: Classification and surgical techniques. ESHRS J 2003;3:6-7.  Back to cited text no. 16

Correspondence Address:
Dr. Muhammad Ahmad
Hair Transplant Institute, House No. 1-B, Main Kohistan Road, F-8/3, Islamabad
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Source of Support: None, Conflict of Interest: None

DOI: 10.4103/0974-2077.191652

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  [Figure 1], [Figure 2], [Figure 3], [Figure 4]

This article has been cited by
1 Revised NPRT Classification System Encompasses Additional Patterns of Male and Female Hair Loss
Muhammad Ahmad, Muhammad Humayun Mohmand
International Society of Hair Restoration Surgery. 2020; 30(3): 81
[Pubmed] | [DOI]


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