title: Hair pull test: Evidence-based update and revision of guidelines.
abstract: 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.
  
  
  CONCLUSIONS
  Participant hair washing and brushing could not be controlled during the study, but this information was documented and analyzed.
  
  
  CONCLUSIONS
  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.
authors.affiliation: University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Katherine A
authors.initials: KA
authors.lastname: McDonald
authors.affiliation: University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Amanda J
authors.initials: AJ
authors.lastname: Shelley
authors.affiliation: University of Ottawa, Ottawa, Ontario, Canada.
authors.forename: Sophia
authors.initials: S
authors.lastname: Colantonio
authors.affiliation: Division of Dermatology, Ottawa Hospital, Ottawa, Ontario, Canada. Electronic address: jbeecker@toh.on.ca.
authors.forename: Jennifer
authors.initials: J
authors.lastname: Beecker
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000505:Alopecia / Q000175:diagnosis* / Q000503:physiopathology; D044466:Asian People; D044383:Black People; D019317:Evidence-Based Medicine; D005260:Female; D006197:Hair / Q000187:drug effects / Q000502:physiology*; D006203:Hair Preparations / Q000494:pharmacology; D006801:Humans; D006920:Hygiene; D008019:Life Style; D008297:Male; D008875:Middle Aged; D004364:Pharmaceutical Preparations; D017410:Practice Guidelines as Topic; D012016:Reference Values; D012535:Scalp; D044465:White People; D055815:Young Adult
chemical_list: D006203:Hair Preparations; D004364:Pharmaceutical Preparations
keywords: acute telogen effluvium; alopecia; alopecia areata; anagen effluvium; clinical examination; clinical guidelines; diagnosis; ethnicity; hair; hair loss; hair pull guidelines; hair pull test; hair texture; loose anagen syndrome; traction test; trichology