title: Bioelectrical impedance vector in pre- and postmenarcheal females.
abstract: OBJECTIVE
  To present what is to our knowledge the first study of the effects of puberty on the distribution of bioimpedance vectors.
  
  
  METHODS
  Resistance and reactance (standard, tetrapolar analysis at 50-kHz frequency) were measured in 143 pre- and postmenarcheal Sardinian girls aged 10 to 15 y.
  
  
  RESULTS
  The data agreed well with the reference values proposed for the Italian population. Bioelectrical impedance vector analysis showed a clear differentiation between pre- and postmenarcheal girls, whereas no significant age-related differences were observed within groups. Postmenarcheal girls had a shorter impedance vector (reduced R/H and Xc/H) and a greater phase angle than did premenarcheal girls.
  
  
  CONCLUSIONS
  Sexual maturity is the major cause of differentiation in the body composition of adolescent females. We recommend that this source of variation be considered in clinical and anthropologic analyses of bioelectrical variables.
authors.affiliation: Department of Experimental Biology, Anthropological Science Section, University of Cagliari, Cagliari, Italy.
authors.forename: Roberto
authors.initials: R
authors.lastname: Buffa
authors.forename: Giovanni
authors.initials: G
authors.lastname: Floris
authors.forename: Elisabetta
authors.initials: E
authors.lastname: Marini
mesh_terms: D000293:Adolescent; D000704:Analysis of Variance; D001823:Body Composition / Q000502:physiology*; D002648:Child; D017097:Electric Impedance; D005260:Female; D006801:Humans; D007558:Italy; D008572:Menarche / Q000502:physiology*; D011627:Puberty; D012016:Reference Values; D012741:Sexual Maturation / Q000502:physiology*