The 24-hour bladder diary can provide an accurate record of urinary output, average voided volume, frequency of voiding, and frequency and nature of incontinent episodes, as well as type and volume of fluid intake. Patients are asked to catch and measure their urine output in a measuring cup during any "normal" 24-hour period they choose.
Occasionally, disorders such as diabetes mellitus, diabetes insipidus or excessive caffeine intake, can be discovered through the bladder diary entries. The diary enables the physician to make helpful suggestions regarding the type and amount of fluid intake. For example, many women with lower urinary tract dysfunction believe they should drink eight to 10 large glasses of water per day, thus maintaining an almost constantly full bladder. Such patients will often benefit from being given "permission" by their physician to just drink when they are thirsty. Patients with significant nocturia may benefit from decreasing fluid intake after their evening meal.