title: Monthly haemostatic factor variability in women and men.
abstract: BACKGROUND
  Hormonal status influences haemostatic factors including fibrinogen, factor VII and plasminogen activator inhibitor (PAI-1), and concentrations differ among men, premenopausal and postmenopausal women. This study examines how phases of the menstrual cycle influence variability of fibrinogen, factor VII and PAI-1.
  
  
  METHODS
  We studied 103 subjects (39 premenopausal women, 18 postmenopausal women and 46 men) during three, randomized, 8-week energy- and nutrient-controlled experimental diets in the Dietary Effects on Lipids and Thrombogenic Activity (DELTA) Study. Fasting blood samples were collected weekly during the last 4 weeks of each diet period, and haemostatic factors were quantified. Two linear mixed-effects models were used for fibrinogen, factor VII and PAI-1: one to estimate and compare group-specific components of variance, and the other to estimate additional fixed effects representing cyclical functions of day of menstrual cycle in premenopausal women.
  
  
  RESULTS
  Systematic cyclical variation with day of menstrual cycle was observed for fibrinogen (P < 0.0001), factor VII (P = 0.0012) and PAI-1 (P = 0.0024) in premenopausal women. However, the amplitude of cycling was small relative to the total magnitude of intra-individual variability. In addition, the intra-individual variance and corresponding coefficient of variation observed in premenopausal women did not differ from postmenopausal women and men.
  
  
  CONCLUSIONS
  The variability in haemostatic factors in premenopausal women is no greater than for postmenopausal women or men. Consequently, premenopausal women can be included in studies investigating haemostatic factor responses without controlling for stage of menstrual cycle.
authors.affiliation: Department of Nutritional Sciences, The Pennsylvania State University, University Park, PA, USA; Nutritional Physiology Research Centre, The University of South Australia, Adelaide, Australia.
authors.forename: Alison M
authors.initials: AM
authors.lastname: Hill
authors.forename: Paul W
authors.initials: PW
authors.lastname: Stewart
authors.forename: Mark K
authors.initials: MK
authors.lastname: Fung
authors.forename: Penny M
authors.initials: PM
authors.lastname: Kris-Etherton
authors.forename: Henry N
authors.initials: HN
authors.lastname: Ginsberg
authors.forename: Russell P
authors.initials: RP
authors.lastname: Tracy
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Pearson
authors.forename: Michael
authors.initials: M
authors.lastname: Lefevre
authors.forename: Roberta G
authors.initials: RG
authors.lastname: Reed
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Elmer
authors.forename: Stephen
authors.initials: S
authors.lastname: Holleran
authors.forename: Abby G
authors.initials: AG
authors.lastname: Ershow
mesh_terms: D000328:Adult; D000368:Aged; D004958:Estradiol / Q000097:blood; D005167:Factor VII / Q000378:metabolism*; D005260:Female; D005340:Fibrinogen / Q000378:metabolism*; D006801:Humans; D016014:Linear Models; D007986:Luteinizing Hormone / Q000097:blood; D008297:Male; D008597:Menstrual Cycle / Q000097:blood*; D008875:Middle Aged; D010507:Periodicity; D017395:Plasminogen Activator Inhibitor 1 / Q000097:blood*; D017698:Postmenopause / Q000097:blood*; D017697:Premenopause / Q000097:blood*; D011374:Progesterone / Q000097:blood; D012737:Sex Factors; D055815:Young Adult
chemical_list: D017395:Plasminogen Activator Inhibitor 1; D011374:Progesterone; D004958:Estradiol; D005167:Factor VII; D005340:Fibrinogen; D007986:Luteinizing Hormone
keywords: Controlled dietary intervention; factor VII; fibrinogen; menstrual cycle; plasminogen activator inhibitor