What are Night-time Symptoms?
Patients may experience bladder symptoms that only happen or are worse at night. These symptoms include waking up once or more overnight to urinate (nocturia) and incontinence.
What are the causes?
Nocturia (waking up once or more to pass urine) is a very common complaint. It can result in insufficient rest and tiredness during the day. There are many causes for it. A distinction must be made between those who wake up because of sleep disturbances (eg. sleep apnea) or psychological factors (stress, anxiety) and those who are woken up by a desire to pass urine. The former group go to the toilet because they are awake and are not bothered by any bladder urgency.
Those who are woken by the bladder are classified into those with bladder storage problems and those with high urine output (polyuria).
Bladder storage problems
A bladder may have problems storing urine if it does not empty well in the first place. It does not take long for such a bladder to fill up again and provoke a desire to void. This is seen in patients with an underactive bladder or in men with obstruction from an enlarged prostate (see prostate related bladder symptoms).
Patients with bladder spasms (overactive bladder) or a stiff bladder that does not stretch to hold more urine (poorly compliant bladder) also have problems storing urine.
Other conditions like bladder infections or interstitial cystitis (IC) often cause poor bladder storage.
Polyuria (high urine output)
This can be divided into 24-hour polyuria (high urine output all day long) and nocturnal polyuria (high urine output only at night).
The causes of 24-hour polyuria include high fluid intake, untreated types 1 and 2 diabetes, diabetes insipidus and diabetes associated with pregnancy.
Nocturnal polyuria is defined as nighttime urine output of >20% of the daily total in young adults and >33% in older adults. The causes include heart failure with fluid retention, swelling of the legs, certain drugs like diuretics (fluid tablets) and drinking too much before bed.
Nighttime incontinence can be due to a few causes:
Bed-wetting that has not resolved since childhood (primary nocturnal enuresis)
An underactive bladder with overflow incontinence
Some leakages occur day and night and are continuous and constant. Some causes include:
A severely incompetent sphincter (ring of muscle below the bladder that controls continence) called intrinsic sphincter deficiency (see stress urinary incontinence)
An abnormal connection between the urinary tract and the vagina - fistula
A congenital condition in which the ureter (tube that drains the kidney) can come down and open in another site other than inside the bladder – ectopic ureter
What are the investigations?
A urine analysis is first done to rule out a simple cause like an infection. A bladder diary recording the frequency and volume voided and the fluid intake is very useful to distinguish between the various causes of nocturia and incontinence.
A CT scan or an ultrasound can be done if anatomical abnormalities are suspected.
Urodynamics can be carried out to identify why a bladder would have storage problems. An overactive or underactive bladder and a poorly compliant bladder can be diagnosed with urodynamics.
If diabetes is suspected, the patient will be referred to an endocrinologist. A blood test called HBA1c can be done to give an indication on how well the blood sugar level is controlled in that person with diabetes, over the last 3 months.
If heart failure is suspected, the patient will then be referred to a cardiologist for further investigations.
What are the treatments?
The treatment of these symptoms should be catered according to the cause indentified. Simple measures like restricting evening fluid intake, changing the time of taking a fluid tablet and treatment of sleep apnea can be useful.
Specific medical conditions
Diabetics lose sugar molecules in the urine. These sugar molecules attract water molecules and hence result in a larger volume of urine made. In those with poorly controlled diabetes, they should seek specialist help to achieve better sugar control.
The fluid that accumulates in the legs all day in those with leg swelling, is redistributed in the body and excreted in the urine when that person lies down flat in bed at night. These patients may benefit from the use of compressive stockings during the day, leg elevation during the afternoon and reduction in salt intake.
Bed wetting rarely persists into adolescence (1% by age 15) and treatments involve changes in fluid intake and behavioural therapy (a waking regimen with the aid of alarms and sensors). In young adults, urodynamics studies should be done to rule out bladder storage problems like an overactive bladder. Medications such as a bladder-calming drug (for OAB) or ADH (anti-diuretic hormone) may be useful in some cases.
Medications can be helpful in some patients. In those with an overactive bladder, medications to calm the bladder can be effective. A medication called ADH can help to reduce nighttime urine output and is used in select patients. There is a risk in electrolyte imbalance (low sodium) and exacerbating heart failure, so it is generally not recommended in the elderly.
Surgery may be indicated if the underlying problem is prostatic obstruction in men. In patients with overactive bladder who do not respond to medications, Anti-spasm bladder injection or sacral neuromodulation (bladder pacemaker) may be tried.