Bladder Clinic article on Nocturia features in Cystitis and Overactive Bladder(Cob) Foundation's Spring Newsletter

Nocturia

HJ Zeif, YZ Almallah
Department of Urology
The Queen Elizabeth Hospital, University Hospital Birmingham NHS Foundation Trust

1. Introduction:
Nocturia is the need to get up during the night in order to pass urine (in contrast to nocturnal enuresis where urine is unintentionally passed during sleep as often seen in children). A single episode of nocturia per night is considered within normal limits. Therefore the term nocturia generally refers to waking up to pass urine more frequently than normal meaning more than once per night. In medical terms ‘nocturia’ describes a symptom and is not considered a diagnosis. It is common in both men and women becoming more frequent in older age. If frequent it can be disruptive to sleep and cause tiredness during the day hence having a significant impact on quality of sleep and quality of life. In the elderly it represents a significant risk factor for accidental falls and injuries at night time and accounts for many emergency hospital admissions.

2. Causes of nocturia:
There are many recognised causes of nocturia such as e.g. heart failure and diabetes. Often these conditions have gone unrecognised for quite some time before patients represent to their doctor with nocturia. This explains why it is important to find out the underlying cause. Generally speaking the reasons for nocturia can be divided into three categories. Problems with fluid balance, neurological conditions which affect bladder function and control and disorders of the lower urinary tract (i.e. the bladder and urethra).

Fluid balance problems can lead to production of excess urine volumes (polyuria). Possible causes include excessive drinking especially before going to bed as well as diabetes, kidney failure, high calcium levels in the blood (hypercalcaemia), treatment with water tablets (diuretics, e.g. bendroflumethiazide) and sleep apnoea. In the elderly heart failure can lead to the redistribution of body fluids from pending areas (swollen ankles and legs) when lying down at night time. Nocturnal polyuria is a condition when more than 35% of the average daily urine production is urinated during the night. This is usually either caused by heart failure or a hormone problem. Vasopressin (or antidiuretic hormone) is a hormone which controls urine production by the kidneys. Vasopressin is normally released into the blood stream in a circadian rhythm. This normally prevents excessive urine production at night time. In the elderly this rhythm often gets weaker or lost causing nocturia.

The bladder’s main functions are the storage of and controlled release of urine. These two functions are closely controlled by the brain which in turn depends on nerves travelling down the spinal column to the bladder and back. This explains why neurological conditions such as e.g. slipped lumbar discs, spinal cord compression by tumours or injury can cause nocturia. Multiple sclerosis, Parkinson’s disease, diabetes, birth defects such as spina bifida or inflammatory diseases such as transverse myelitis can also affect the way the bladder works. Sometimes this can lead to the involuntary retention of urine resulting in increased urinary frequency or even leakage (overflow incontinence). This can be misinterpreted as nocturia and can lead to a missed diagnosis. Doctors are commonly well advised to look for neurological symptoms in women or younger patients who present in urinary retention. They are less likely to suffer with bladder outflow obstruction or medical conditions which commonly affect the elderly age group.

Disorders of the lower urinary tract comprise bladder outflow obstruction (chronic urinary retention) caused by either pregnancy, prostatic or urethral disease. Age related prostatic enlargement (benign or cancer related) can lead to partial or complete retention of urine. This leads to frequent urination of small volumes or sometimes leakage if the ‘bursting point’ of the full bladder is reached. Sensitivity, overactivity, infection, inflammation (e.g. interstitial cystitis) or cancer of the bladder can also affect the lower urinary tract. These conditions usually do not occur in isolation at night time but also throughout the day distinguishing them from nocturia per se. Nocturia in men is often put down to prostate problems, without due consideration of other causes or a possible combination of factors, which can just as likely be the cause(s). Benign prostatic enlargement often occurs in presence of or with diabetes, heart or kidney failure.

Most times doctors can identify the underlying reason for nocturia by asking questions, performing an examination, asking the patient to fill in a fluid and voiding diary and sometimes with the help of a bladder function test called urodynamics.

3. Treatment
Treatment should be guided by the underlying cause. The severity of symptoms and their impact on quality of life and sleep also play an important part. Treatment is not always required for as long as the patient is not bothered by his symptoms and not at risk of short or long-term complications such as e.g. kidney failure.

Fluid advice consists of cutting down on ‘bad’ fluids such as alcohol, tea, coffee or fizzy drinks which can have a negative or worsening effect on bladder symptoms. Drinking late at night should also be avoided and bladder emptying before going to bed encouraged. Following these basic measures alone can help a great number of patients to improve their nocturia. Age related prostatic enlargement (both benign and in cancer) can be treated by drugs, surgery or a combination of both. Catheterisation (introduction of a drainage tube into the bladder) represents a valuable alternative in patients unsuitable for drug treatment or surgery. However it is not well tolerated by all patients and carries potential risks such as recurrent infections, bladder stone or scar tissue formation (urethral stricture). Excessive thirst can be suggestive of diabetes (mellitus or insipidus) requiring medical treatment. Heart failure is sometimes treated with drugs which can in themselves cause increased urine production (water tablets or diuretics).

Whatever the underlying cause patients are well advised to inform their doctor if nocturia becomes a problem. Possible underlying causes include a variety of potentially debilitating and dangerous conditions which may otherwise have been gone unnoticed.

For further information please visit
www.thebladderclinic.co.uk or www.cob.org.