Presenting a New Non-Invasive Diagnostic Tool in Estimating Bladder Capacity in Healthy Children: The Abc (Age-Related Bladder Capacity)-Formula

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      Estimating the bladder capacity is highly important in diagnosing voiding or bladder dysfunction in children. The convenient formula, the Koff formula (bladder capacity (in ounces) = age (in years) + 2), has been established as gold standard. Despite its relevance, it shows certain weaknesses, especially in young children. It is often associated with larger bladder volumes and higher daily fluid intake. The aim of this study was to develop a formula which puts bladder capacity in association with age and micturition frequency.

      Material and Methods

      We examined prospectively the bladder diary in 60 children with no voiding or bladder dysfunction, which were seen for other urological problems. We differentiated three age groups of children.
      Group 1: little children aged 5-7, (n = 20)
      Group 2: small school children aged 8-10 (n = 20)
      Group 3: big school children aged 11-15 (n = 20)
      After computerized evaluation, an equation got developed out of these micturition data.


      Tabled 1
      Age Micturition frequency Micturition vol. (ml)

      (acc. ABC-formula)
      Daily amount of urine (ml)
      5 6-7x/d 75 450-525
      6 90 540-630
      7 105 630-735
      8 5-6x/d 120 600-720
      9 135 675-810
      10 150 750-900
      11 4-5x/d 165 660-825
      12 180 720-900
      13 195 780-975
      14 210 840-1050
      15 225 900-1125
      The results are represented in table 1. Table 1: parameter marks for healthy children in relation to the ABC-formula


      The formula presented shows its relevance based on the co-parameter age, micturition frequency and bladder capacity. It is thought to be a useful guide for diagnosing voiding and bladder dysfunctions. With the ABC-formula [(Age x 30)/2], bladder capacity in healthy children can be determined exactly.
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