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The severity of Alopecia Areata (AA) is typically measured with the Severity of ALopecia Tool (SALT) Score^1,2 . The SALT Score is computed by measuring the percentage of hair loss in each of the 4 areas of the scalp — the right profile (accounting for 18% of the total scalp area), the left profile (18%), the vertex (40%), and the posterior (24%), see also figure 4 below. By adding the total procentage of hair loss for each region multiplied by the regions relative area, one achieves a composite total score ie the SALT Score. Hair regrowth is reflected by a decrease in the SALT score (eg, complete hair regrowth would confer a SALT score of 0). Below you will find a simple tool that does the SALT SCORE calculation based on hair loss in each of the above mentioned regions.

Figure 1: Definition of the four main scalp areas associated with the SALT Score.
Image copyright: Kirsten Rønholt site author

1: Olsen EA, Hordinsky MK, Price VH, Roberts JL, Shapiro J, Canfield D, et al. Alopecia areata investigational assessment guidelines–part ii. National alopecia areata foundation. J Am Acad Dermatol. 2004;51:440–447

2: Olsen EA, Roberts J, Sperling L, Tosti A, Shapiro J, McMichael A, Bergfeld W, Callender V, Mirmirani P, Washenik K, Whiting D, Cotsarelis G, Hordinsky M. Objective outcome measures: Collecting meaningful data on alopecia areata. J Am Acad Dermatol. 2018 Sep;79(3):470-478.e3