title: Bladder diary measurements in asymptomatic females: functional bladder capacity, frequency, and 24-hr volume.
abstract: OBJECTIVE
  To study the effects of age and 24-h volume (V(24)) on bladder diary measurements of voiding frequency (F(24)) and functional bladder capacity (FBC) from an asymptomatic female population. Also, to use these data to develop clinical reference values. (We use FBC as a generic term for bladder diary volume-per-void measurements.)
  
  
  METHODS
  Computer-processed 3-day bladder diaries were collected from 161 females (median age: 46.6 years; range = 19.6-81.8 years) claiming no urological symptoms, previous pelvic surgery and diseases and medications effecting urologic function. Regression analysis was used to investigate relationships among age, FBC and V(24).
  
  
  RESULTS
  Both FBC and F(24) increase as V(24) increases (P < 0.0005). With aging, F(24) increases (P = 0.026) and FBC may decrease slightly (P = 0.02-0.08). There is a concave downward, curvilinear relationship between age and V(24). We used multiple regression to generate tables of FBC and F(24) "normal limits" adjusted for these simultaneous influences of V(24) and age. Removing their relationships to age reduces the variability of FBC and F(24) reference values by 50% and 20%, respectively.
  
  
  CONCLUSIONS
  Our finding, supported by others, that, with increasing V(24), FBC increases more than F(24) suggests an adaptive mechanism that adjusts FBC to urine production to minimize changes in voiding frequency. We illustrate adjustment of reference values for age and V(24) by calculating traditional clinical "normal limits." However, the probable large overlap between "normal" and "abnormal" suggests that it may be more useful to report bladder diary measurements as reference population percentiles rather than to designate them "normal" or "abnormal".
authors.affiliation: Department of Obstetrics and Gynecology, Division of Urogynecology, Duke University Medical Center, Durham, North Carolina 27110, USA. amund@mc.duke.edu
authors.forename: Cindy L
authors.initials: CL
authors.lastname: Amundsen
authors.forename: Matthew
authors.initials: M
authors.lastname: Parsons
authors.forename: Bill
authors.initials: B
authors.lastname: Tissot
authors.forename: Linda
authors.initials: L
authors.lastname: Cardozo
authors.forename: Ananias
authors.initials: A
authors.lastname: Diokno
authors.forename: Alfred C
authors.initials: AC
authors.lastname: Coats
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D003950:Diagnostic Techniques, Urological / Q000592:standards* / Q000706:statistics & numerical data; D005260:Female; D006801:Humans; D008499:Medical Records / Q000706:statistics & numerical data*; D008875:Middle Aged; D010358:Patient Participation; D011177:Postal Service; D012016:Reference Values; D012044:Regression Analysis; D001743:Urinary Bladder / Q000502:physiology*; D053201:Urinary Bladder, Overactive / Q000175:diagnosis* / Q000503:physiopathology; D014549:Urinary Incontinence / Q000175:diagnosis* / Q000503:physiopathology; D014563:Urodynamics / Q000502:physiology*