Andrew Siegel, M.D. Blog #100
Nocturia is a condition in which one awakens from sleep to urinate. Arising once or so to empty one’s bladder during sleep hours is considered normal; however, when it happens multiple times, it can be not only annoying but also sleep-disruptive. It is common in both men and women and increases in prevalence as we age. It is primarily a kidney-driven urine production problem, as opposed to a bladder-driven urine storage issue.
As with many matters, nocturia is more complicated than it appears and is often multi-factorial. That stated, it is important to reiterate that the most common underlying cause of nocturia is nocturnal overproduction of urine. Although most associate the occurrence of nighttime urination with lower urinary tract conditions, in many cases the problem is actually due to the kidneys (upper urinary tract) and not the bladder and prostate (lower urinary tract). Nighttime urine overproduction, a.k.a. nocturnal polyuria, may result from kidney issues, but also from cardiac or lung conditions. Nocturnal overproduction of urine at night has been implicated as a causal factor in over 80% of cases of nighttime urination.
Nocturia can certainly occur on the basis of lower urinary tract conditions, particularly with benign prostate enlargement or overactive bladder. Under these circumstances, the nocturnal urinary frequency is often on the basis of decreased bladder capacity (in which the bladder is incapable of storing normal volumes) or sometimes because of failure to empty the bladder (in which the bladder is always left partially full). Additionally, any source of bladder irritation such as an infection, stone, cancer, etc., can irritate the lining of the bladder and cause nighttime urination. Nocturia can be induced by extrinsic pressure on the bladder, seen with fibroids of the uterus and rectal fullness due to either gas or constipation, although it can be caused by the presence of any pelvic mass. Nocturia can also occur on a neurological basis since neurological diseases such as stroke, spinal cord injury, multiple sclerosis, Parkinson’s disease, etc., can affect urinary frequency during sleep. Even when nocturia is caused primarily by prostate enlargement, overactive bladder, bladder irritation or a neurological issue, etc., nocturnal overproduction can contribute to the process.
Why does nocturnal overproduction of urine occur? It can result from a number of factors such as the mobilization of excess fluid stored in the lower extremities in people who have peripheral edema. Edema refers to fluid within the tissues–typically the ankles–that tends to accumulate with gravity over the course of the day. Upon assuming the lying-down position when sleeping, the legs are relatively elevated as opposed to standing and this tissue fluid returns into circulation, causing the kidneys to increase urine production. In general, those with peripheral edema go to sleep with ankles (and perhaps legs) engorged with edema fluid and wake up with thinner legs, as the return of some of the fluid to the circulation and the subsequent increased urination rids them of this. Another underlying cause is excessive production of atrial natriuretic peptide due to sleep apnea or congestive heart failure. Yet another possibility is an abnormality in the nocturnal secretion of anti-diuretic hormone. This pituitary hormone functions to cause the kidneys to retain fluid; nocturia may occur because of an age associated decline in its secretion while sleeping. Other factors include excess fluid intake in the evening, especially caffeine-containing beverages, and the use of medications such as diuretics. Systemic diseases such as diabetes mellitus, diabetes insipidus, and kidney insufficiency, can all cause nocturnal polyuria.
Sometimes nighttime urination occurs not because of any systemic illness or bladder, prostate, kidney or overproduction issue, but simply because of poor sleep. When sleeping poorly, one often gets up to urinate because the wakeful state makes one more conscious of their bladder being full, or alternatively, for an activity to occupy time during the insomnia. Any sleep disorder—insomnia, obstructive sleep apnea, restless leg syndrome, etc.—can result in poor quality sleep and often nocturia. The bladder is a convenient outlet for anxiety, which can induce urinary frequency.
The principal diagnostic tool for assessing nocturia is a voiding diary in which the time and the volume of urination are recorded for a 24-hour period. There are 4 major findings that may occur: reduced bladder capacity; global polyuria; nocturnal polyuria; or a mixed pattern. Typical bladder capacity is 10–12 ounces with 4–6 urinations per day. Reduced bladder capacity is a condition in which frequent urination occurs with low bladder capacities, for example, 3–4 ounces per void. Global polyuria is a condition in which bladder volumes are full and appropriate and the frequency occurs both daytime and nighttime. Nocturnal polyuria is nocturnal urinary frequency with full and appropriate volumes, with daytime voiding patterns being normal. A mixed pattern can be a more complex picture involving elements of the other patterns.
If fluid intake is found to be excessive, simple moderation of intake will be helpful, particularly with respect to caffeinated beverages and high fluid content foods such as melons and other fruits. Restricting liquid intake after dinner is often advisable. Minimizing high salt content foods and table salt can help prevent fluid retention. If edema is the issue, compression stockings worn during the day as well as elevating the legs during the day can be of value in getting some of the interstitial fluid out of the system. Diuretics taken during the late afternoon may decrease fluid accumulation.
Medications may be helpful, depending upon the cause of the nocturia. Synthetic antidiuretic hormone, aka DDAVP which is useful for childhood bedwetting, can be useful for adults with nocturia associated with nocturnal polyuria. Bladder relaxing medications as well as behavioral techniques and pelvic floor exercises can be beneficial for overactive bladder. Prostate relaxing and shrinking medications or surgical treatment can be helpful if an enlarged prostate is the cause.
Nighttime urination is one of the most annoying and bothersome of urinary symptoms given how sleep-disruptive it often proves to be. Chronically disturbed sleep can negatively affect one’s quality of life and health. It can result in daytime fatigue, increased risk of traffic accidents, increased incidents of fall-related nighttime injuries, and weight gain because of altered eating patterns. Insufficient sleep alters our internal biochemical environment and can profoundly disrupt our eating drives leading to patterns of “promiscuous eating.” Clearly, there appears to be a physiological basis for this fatigue-driven eating. Sleep deprivation or the need for sleep results in decreased levels of leptin, our chemical appetite suppressant, and increased levels of ghrelin, our appetite stimulant, in addition to increased levels of cortisol, one of the stress hormones. This sleep-deprived change of our internal chemical milieu can drive our eating. Therein lies the link between urology and nutrition/health/wellness that I am so fond of establishing.
Bottom Line: Nocturnal urinary frequency should be investigated to determine its cause, which may in fact be related to conditions other than urinary tract issues. Nighttime urination is not only bothersome, but may also pose real health risks. Chronically disturbed sleep can lead to a host of collateral wellness issues.
Andrew Siegel, M.D.
Author of Promiscuous Eating: Understanding and Ending Our Self-Destructive Relationship with Food: www.promiscuouseating.com
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Tags: benign prostate enlargement, bladder cancer, bladder diary, congestive heart failure, extrinsic compression, neurological diseases, nocturia, nocturnal polyuria, obstructive sleep apnea, overactive bladder, peripheral edema, promiscuous eating, urinary infection, uterine fibroids