One of the most common and disturbing symptoms prompting a consultation with a urologist — the medical specialist who deals with urinary issues — is nighttime urination (aka nocturia), which is often sleep-disruptive and causes daytime fatigue.
Getting up once is usually tolerated, but when it occurs two or more times, it can be problematic, with many finding it difficult to get back to sleep.
Nocturia is also responsible for an increased risk of fatigue-related accidents and fall-related nighttime injuries during the frequent trips to the bathroom in the dark.
Causes Of Nocturia
Although nocturia often has a urologic basis, that is not always the case. Therefore, it is important to seek the underlying cause to effectively treat nocturia.
Excessive nighttime urine production, sleep issues, and diminished bladder capacity are the major three general causes of nocturia. Several of these factors can coexist.
In the older population, excessive nighttime urine production is the most common culprit. The first thought for many men suffering with nocturia is that the prostate must be responsible.
Although the prostate may certainly play a role, it is often far more complicated than this, since nocturia is equally prevalent in men and women (and women lack prostates).
1. Excessive Urine Production
Since urine production by the kidneys is proportional to fluid intake, nocturia can result from excessive fluid consumption, particularly caffeinated beverages or alcohol, especially when consumed late in the evening.
Diabetes often causes frequent urination because of the diuretic (water pill) effect of glucose. Moreover, many medications may induce frequent urination. Edema, aka fluid accumulation in the legs and other tissues, causes nocturia because when sleeping, the fluid is no longer under gravitational pressure and returns to the circulation. This is why those with leg edema often have the greatest swelling in the evening hours and the least in the morning hours.
Nighttime urination commonly occurs because of an age-related decline in kidney function (one of which is to concentrate urine), which results in higher volumes of more dilute urine. Two hormones govern nighttime urine production: anti-diuretic hormone (ADH) and atrial natriuretic peptide (ANP). ADH functions to restrict urine production (to ensure that we do not dehydrate). On the other hand, ANP is a diuretic that increases urine production.
Nocturia can occur because of the decline in nighttime ADH release, unresponsiveness of the kidneys to the action of ADH, or excessive ANP, all three of which can accompany the aging process.
2. Sleep Issues
Insomnia often leads to frequent visits to the bathroom. When awake, tossing and turning, not only is one more aware of their bladder fullness, but, not uncommonly, more frequent trips are made to the bathroom simply as something to do, not necessarily because one needs to.
Obstructive sleep apnea (OSA) is a major and increasingly recognized cause of nocturia. This is condition is estimated to occur in up to 30% of men and is characterized by the collapse of the soft tissues of the throat while sleeping, resulting in snoring and obstruction to the inflow of oxygen. Breathing against an obstructed airway results in negative chest pressures and an increase of blood return to the heart. The heart falsely senses fluid overload and secretes ANP, causing production of large volumes of urine. It is not uncommon for patients with sleep apnea to awaken six or more times to urinate; remarkably, when treated, the nocturia often disappears.
3. Urological Causes
Overactive bladder — the bladder “squeezing without its owner’s permission” — is a common cause of nocturia as are incomplete bladder emptying due to prostate enlargement, urethral scar tissue, dropped bladder, and nerve issues affecting bladder function. Any form of bladder irritation can also cause frequent urinating: cystitis, bladder stones, bladder cancer, etc.
The principal diagnostic tool is a bladder diary, a simple test that can effectively guide diagnosis and treatment. This is a 24-hour record of the time and volume of urination, requiring a watch, pen, paper, and measuring cup. Normal bladder capacity is 10–12 ounces, and typical frequency of urination is 4–6 times per day. Small-volume nocturia is most often due to urological causes, whereas full-volume nocturia is due to non-urological issues.
Depending on the results of the diary, more sophisticated tests may be necessary to pinpoint the source of the nocturia.
Lifestyle modifications to improve nocturia include:
- Preemptive urinating before bedtime
- Intentional nocturnal and late afternoon dehydration
- Salt restriction
- Dietary restriction of caffeine and alcohol
- Adjustment of medication timing
- Use of compression stockings, with afternoon and evening leg elevation
- Use of sleep medications as necessary
Urological issues may need to be managed with medications that relax or shrink the prostate when the issue is prostate obstruction, with bladder relaxants for overactive bladder. For full-volume nocturia, synthetic ADH (an orally disintegrating sublingual tablet) can be highly effective.
Nocturia is a common and bothersome condition and should be investigated to determine its cause, which may often be related to conditions other than urinary tract issues. Nighttime urination is not only annoying and disruptive to sleep, but the chronically disturbed sleep can pose real health risks. The good news is that it is a very treatable problem.