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Dr. Udaya Kumar, Urology Today, 01/29/13

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Does the bladder have a clock?

Many of our bodily functions are subject to the influence of the circadian rhythm.

This rhythm is related to the biological clock which dictates the mental, physical and behavioral changes that follow a roughly 24-hour cycle of light and darkness.

The circadian rhythm can be observed in most living organism including animals, plants and even tiny microbes. This natural oscillation influences the sleep-wake cycles, hormonal secretion, body temperature and kidney function.

The master clock that regulates the various circadian rhythms of the body resides in a group of nerve cells in the brain called the suprachiasmatic nucleus, or SCN, in the hypothalamus.

Imbalances or disruption to these circadian rhythms have been linked to several problems, including sleep disorders, obesity, depression and diabetes.

It has long been observed that kidney functions including urine production exhibit daily oscillations. Urine production is influenced by a hormone called anti-diuretic hormone (ADH), which also fluctuates according to the circadian rhythm. Sleep deprivation and other imbalances can cause a reversal of the pattern of urine production, causing increased nighttime urine production with resulting nocturia, or nighttime urinary frequency.

Increased nighttime urinary frequency, or nocturia, is often the most bothersome symptom of bladder problems experienced by men and women.

Nocturia and poor sleep can adversely affect the quality of life, productivity at work and may even result in falls and fractures among the elderly.

While change in the circadian rhythm in anti-diuretic hormone production and increased urine production at night is one of the main causes of nocturia, several other conditions have to be considered by the physicians treating nocturia. Reduced capacity of the bladder, enlarged prostate in men, congestive heart failure, the use of diuretics (water pills), poorly controlled diabetes, sleep apnea, kidney disease and edema are some of the other conditions that may influence urinary frequency at night.

Recoding the urinary frequency and volume for a one- to three-day period may help the physician diagnose excessive production of urine at night and treat accordingly.

The PER2 gene (Period 2 gene) that regulates the circadian rhythm in the brain has also been identified in various body tissues such as the liver, heart and endocrine organs.

Now researchers in the United Kingdom have identified the PER2 gene in mice bladders and found that the activity of the gene oscillated with the 24-hour light/dark cycle.

It has been suggested that derangement in the regulation of the PER2 gene may have a role to play in bladder overactivity and increased nighttime frequency.

Further research on the “bladder-clock” gene may provide us clues to better manage nocturia and overactive bladder. Perhaps we could turn the clock off before going to bed!

Udaya Kumar. M.D., FRCS Urol, Dip. Urol (London), is certified by the American Board of Urology and the Board of Urology of U.K. and Ireland. He is a former professor of urology with University of Arkansas for Medical Sciences. Contact him at 3475 S. Suncoast Blvd., Homosassa, FL 34448 or 352-628-7671.