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Hair pull test: Evidence-based update and revision of guidelines
Katherine A McDonald1, Amanda J Shelley1, Sophia Colantonio1
1University of Ottawa, Ottawa, Ontario, Canada.
Background:
The hair pull test lacks validation and has unclear pretest guidelines.
Objective:
We sought to quantify normal hair pull test values and elucidate the effect of pretest hair washing and brushing. The impact of hair texture and lifestyle was also examined.
Methods:
Participants (n = 181) completed a questionnaire recording demographics, medications, and hair health/history. A single hair pull test (scalp vertex) was performed.
Results:
The mean number of hairs removed per pull was 0.44 (SD 0.75). There was no significant difference in the mean number of hairs removed regardless of when participants washed (P = .20) or brushed (P = .25) their hair. Hair pull test values were similar between Caucasian-, Asian-, and Afro-textured hair. There was no significant difference in hair pull values between participants taking medications affecting hair loss and participants not taking these medications (P = .33). Tight hairstyles did not influence hair pull test values.
Limitations:
Participant hair washing and brushing could not be controlled during the study, but this information was documented and analyzed.
Conclusion:
Normal values for the hair pull test should be reduced to 2 hairs or fewer (97.2% of participants). The current 5-day restriction on pretest hair washing can be reduced and brushing be made permissible.
