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Assessment of nocturia 

Assessment of nocturia
Chapter:
Assessment of nocturia
Author(s):

Marcus Drake

DOI:
10.1093/med/9780198719113.003.0003
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Key points

  • Patients suffering from nocturia need a thorough medical and surgical history and focused clinical examination.

  • Baseline investigations required for patients suffering with nocturia include:

    • height and weight to calculate body mass index

    • bladder diary, e.g. the ICIQ-Bladder Diary

    • symptom and quality of life questionnaires, e.g. ICIQ-N and ICIQ-NQoL

    • urinalysis, e.g. ‘dipstick’

    • flow rate and post-void residual measurement

    • biochemical tests, e.g. renal electrolytes.

  • Further urological investigations, such as urodynamics, cystoscopy, or imaging, are not indicated, unless an abnormality is suspected on baseline investigations and after failure of conservative and medical therapy.

  • Patients are usually referred to the urologist for nocturia. However, following a thorough investigation, patients may need to be referred to another specialty to exclude potential systemic diagnoses, such as sleep disorders, sleep apnoea, or endocrine dysfunction.

3.1 Introduction

Clinical assessment of nocturia aims to establish the severity and QoL impact of the symptom, and also to try to understand underlying mechanisms in individuals affected. In general, more severe nocturia is likely to reflect a worse underlying problem, and it may well have a greater impact on QoL. However, bother levels do not necessarily correspond with symptom severity, since individual attitudes may differ. Sometimes younger people report bother from the symptom, whilst older people might be more accepting of nocturia of similar severity. Accordingly, severity and bother should both be considered.

Nocturia is not only a LUTS, but also an aspect of homeostatic control. Urine output is determined physiologically to eliminate excess free water (diuresis) or excess salt (natriuresis); some conditions can lead to excessive free water or salt excretion beyond that needed physiologically. Thus, nocturia (usually in the form of nocturnal polyuria) or 24-hour polyuria (in which night-time and daytime overproduction of urine are both present) can reflect systemic conditions or problems with renal tubular function.

Clinical assessment is directed at deciding firstly whether there might be an underlying medical condition of which the management needs to be optimized or which has yet to be recognized in the person affected, and secondly whether the nocturia needs treatment as a symptom in its own right. As with any other clinical presentation, clinical assessment starts with history, which usefully can be supplemented by symptom assessment questionnaires. Modern questionnaires have been validated to score symptom severity and bother for all LUTS, which makes taking the history more efficient and comprehensive. A frequency/volume chart is crucial for guiding the evaluation of underlying mechanisms. Special investigations may be needed in certain contexts.

3.2 History and examination

The presence of LUTS in the categories of storage or voiding/post-micturition needs to be ascertained. The most widely used definitions of LUTS are the standardized terms defined by ICS (Table 1.1).

Nocturia should be diagnosed if the individual has to wake at night one or more times to void [1, 2]. The term ‘night-time frequency’ differs from that for nocturia, as it includes voids that occur after the individual has gone to bed, but before he/she has gone to sleep, and voids which occur in the early morning which prevent the individual from getting back to sleep as he/she wishes [1]. If this definition is used, then an adapted definition of daytime frequency would need to be used with it.

The presence of a range of LUTS, in addition to nocturia, suggests lower urinary tract dysfunction may be a contributory aspect of nocturia, although additional contributory factors do still need to be considered. The presence of enuresis should be sought by questioning as to whether the patient passes urine, whilst remaining asleep, and thereby wets nightclothes and the bed. Nocturia can also be an aspect of bladder pain syndrome, so the presence of pain related to bladder filling, relieved by emptying, should be enquired after. Symptom assessment questionnaires are a time-effective means of comprehensively and systematically capturing relevant features. In the field of nocturia, there are dedicated questionnaires for nocturia severity and QoL impact. The International Consultation on Incontinence Modular Questionnaire (ICIQ) has developed specific questionnaires for nocturia (ICIQ-N) (Figure 3.1) [3] and QoL impact of nocturia (ICIQ-NQol) (Figure 3.2) [4]. These are particularly useful where nocturia is a predominant symptom.


Figure 3.1 International Consultation on Incontinence Modular Questionnaire (ICIQ) questionnaires for nocturia (ICIQ-N).

Figure 3.1 International Consultation on Incontinence Modular Questionnaire (ICIQ) questionnaires for nocturia (ICIQ-N).

Reproduced with permission from ICIQ.net. The Journal of Urology, 175(3), Abrams et al., The International Consultation on Incontinence Modular Questionnaire: <http://www.iciq.net>, pp. 1063–1066, Copyright (2006).


Figure 3.2 International Consultation on Incontinence Modular Questionnaire (ICIQ) questionnaires for quality of life impact of nocturia (ICIQ-NQol).

Figure 3.2 International Consultation on Incontinence Modular Questionnaire (ICIQ) questionnaires for quality of life impact of nocturia (ICIQ-NQol).

(Reproduced from Urology, 63(3), Abraham et al., Development and validation of a quality-of-life measure for men with nocturia, pp. 481–486, Copyright (2004), with permission from Elsevier.)

Where other LUTS are also prominent, broader symptom assessment tools, such as the ICIQ-Male LUTS (ICIQ-MLUTS) and ICIQ-Female LUTS (ICIQ-FLUTS) tools, provide an assessment of all lower urinary symptoms, rating both severity and bother. In the ICIQ-MLUTS questionnaire, the specific question related to the nocturia is ‘During the night, how many times do you have to get up to urinate on average?’, scored between 0 and 4. This is immediately followed by the question ‘How much does this bother you?’, rated from 0 to 10 (‘not at all’ to ‘a great deal’). There is also a question ‘Do you leak urine when you are asleep?’, also scored from 0 to 4, and again linked to a specific bother question.

Nocturia also features in the well-known International Prostate Symptom Score (IPSS) where the relevant question is ‘How many times do you typically get up at night to urinate?’, scored from 0 to 5, averaged over the preceding month. For the IPSS, bother is scored globally for all LUTS, rather than for each individual LUTS. Recently, a slightly simplified questionnaire, called the ‘Urgency, Weak stream, Incomplete emptying, and Nocturia’ (UWIN) score, has been introduced and validated [5]. Questionnaires can also be used to assess sleep, of which the Pittsburgh Sleep Quality Index (PSQI) is a well-known example [6].

During history-taking, enquiries should be made regarding habits such as fluid intake and sleep environment. Evening intake of fluid volume, caffeinated drinks, or alcoholic beverages should be captured, and also the type and time of meals in the evening as many foods contain mainly water such as fruits, salads, and vegetables. The sleep environment should be considered, e.g. noise levels and temperature. The mental state should also be considered. Anxiety and depression can be significant contributors to difficulty sleeping. The possibility of undiagnosed underlying depression should be considered, and a simple screening measure, such as the hospital anxiety and depression scale (HADS), may be appropriate. For some patients, anxiety or depression may be precipitated by their LUTS [7]. For some patients, they may be concerned about the possibility of underlying malignancy as a cause of their LUTS. Many male patients can be concerned that prostate cancer is a factor in LUTS, and simple screening and reassurance can be a suitable measure in such cases.

The past medical history should be screened, focusing on known conditions which can be relevant in urine production. These include endocrine dysfunctions such as diabetes mellitus or diabetes insipidus. Congestive cardiac failure, renal dysfunction, pulmonary disease, and neurological disease are potentially relevant [8]. The possibility of an as yet undiagnosed medical condition should also be considered. Questions related to erectile dysfunction, shortness of breath, swelling of ankles, and nocturnal breathing interruptions may be appropriate. Additionally, a past medical history of conditions or medications affecting sleep should be considered. A list of medications which can affect urine output or sleep quality is given in Table 3.1.

Table 3.1 Medications affecting urine output or sleep

Increased urine output

Direct lower urinary tract effects

Insomnia and central nervous system effects

Diuretics

Ketamine

CNS stimulants (dexamfetamine, methylphenidate)

Calcium channel blockers

Tiaprofenic acid

Antihypertensives (alpha-blockers, beta-blockers, methyldopa)

Tetracycline

Cyclophosphamide

Respiratory (salbutamol, theophylline)

Lithium

Decongestants (phenylephrine, pseudoephedrine)

Hormones (corticosteroids, thyroid)

Psychotropics (MAOIs, SSRIs, atypical antidepressants)

Dopaminergic agonists (carbidopa)

Anti-epileptics (phenytoin)

CNS, central nervous system; MAOI, monoamine oxidase inhibitor; SSRI, selective serotonin reuptake inhibitor.

(Adapted from BJU International, Gulur et al., Nocturia as a manifestation of systemic disease, Copyright (2011), with permission from John Wiley and Sons.)

Physical examination should include a general medical examination, with additional focused examination to look at the body habitus (in case of the possibility of obstructive sleep apnoea) and the abdomen to look for any abdominal or pelvic masses that are compressing the bladder or a palpable bladder or kidneys, pelvic examination, and evidence of fluid retention (dependent oedema, usually seen as swollen ankles).

Examination should also include a digital rectal examination in men and vaginal examination in women to look for prolapse, oestrogen status, anal tone and sensation, and pelvic squeeze as well as a neurological examination of the lower limbs. This may help to diagnose a neurological problem, which can be relevant in nocturia.

A cardiovascular and respiratory examination needs to be performed to rule out any congestive cardiac failure signs, especially pitting oedema of the lower limbs and any sign of wheeziness in the chest which may cause shortness of breath at night, causing the patient to rise and void.

Following this, some simple bedside tests can be performed. These include measurement of the height and weight to calculate the body mass index, and therefore help diagnose obesity which can be a factor in causing sleep apnoea. Measurement of blood pressure may help in the diagnosis of cardiac or renal problems.

3.3 Bladder diary

History alone is unreliable at cataloguing urine volumes, and a frequency/volume chart (FVC) or bladder diary measured over at least 3 days is an essential element in the assessment of nocturia [9]. The number of days that an FVC needs to be completed depends on the information required. FVCs can vary from 1-day to 14-day charts. ICS recommends that, for nocturia, an FVC has to be for 24–72 hours. However, in our opinion, 24 hours is not very informative, as nocturia may vary from day to day and depends on the individual’s drinking habits, as mentioned earlier; thus, it may be worse at weekends, compared to weekdays, when some patients may drink in greater amounts, e.g. several beers on a Saturday night. Also, it may be difficult to assess other LUTS, such as daytime frequency and incontinence, with a 1-day chart.

Written instructions on an FVC are normally adequate for most patients, and intensive personal instruction is not necessary. We normally send an FVC to patients with their clinic appointment, as this saves them having to attend another clinic appointment, and they can have a diagnosis and treatment initiated sooner rather than later.

We have used a 7-day FVC until recently, as this would include weekends and weekdays, but patients sometimes had difficulty completing them, especially if they are working. We have now changed to a 3-day FVC, based on evidence that a 3-day chart gives the same information as, if not better than, a 7-day FVC. The FVC, for purposes of nocturia, should include recording the time of going to bed with the intention of sleeping and the time of rising with the intention of getting up for the day.

The FVC provides the most important objective information, as it enables the categorization of patients into those with 24-hour polyuria, nocturnal polyuria, sleep disturbance, or reduced nocturnal bladder capacity [10]. This can be differentiated easily through mathematical analysis of the chart, which can give a range of useful information (Table 3.2) [11]. The key points to note are whether there is polyuria (an overall urine output in excess of 40 mL per kg body weight per 24 hours), nocturnal polyuria (where more than a third of the 24-hour output is made during the hours of sleep), and whether there are frequent voids of small volume. The FVC can also be used to evaluate the sleep duration (Table 3.2).

Table 3.2 Parameters of nocturia derived from a frequency/volume chart (FVC)

Parameter

Description

Actual number of nightly voids (ANV)

Night-time voids observed from the FVC

Functional bladder capacity (FBC)

Largest single recorded voided volume from the FVC (equals the maximum voided volume)

Nocturnal urine volume (NUV)

Night-time voided volumes plus first morning voided volume

Nocturia index (Ni)

NUV/FBC

Predicted number of nightly voids (PNV)

Ni − 1

Nocturnal bladder capacity index (NBCi)

ANV − PNV

Nocturnal polyuria index (NPi)

NUV/24-hour total voided volume

(Adapted from The Journal of Urology, 175(3), Jeffrey Weiss, Nocturia: ‘Do the Math’, pp. 16–18, Copyright (2006), with permission from Elsevier.)

The FVC can be supplemented by additional information such as fluid intake or symptom scores [12] (Figure 3.3). It is then known as a bladder diary, according to ICS standardized terminology. Without the FVC, the diagnoses cannot be made, and therefore inappropriate treatment may be given, resulting in a waste of the patient’s time and of health service resources. Thus, the FVC forms the most important and indispensable part of the evaluation of nocturia.See Table 3.3 for an example FVC analysis.


Figure 3.3 International Consultation on Incontinence Questionnaire Bladder Diary (ICIQ-BD).

Figure 3.3 International Consultation on Incontinence Questionnaire Bladder Diary (ICIQ-BD).

(Adapted from European Urology, 66(2), Bright et al., Developing and Validating the International Consultation on Incontinence Questionnaire Bladder Diary, pp. 294–300, Copyright (2014), with permission from Elsevier.)

Table 3.3 Example of FVC analysis

Daytime(from waking up to going to bed)

Night-time(from going to bed to getting up)

Time

Voided volume (mL)

Time

Voided volume (mL)

Time of waking up: 07.00

200

Time of going to bed: 22.05

Watching TV in bed

08.15

200

23.00

200 (Fell asleep at 23.30)

12.00

350

01.00

200

16.30

400

03.00

300

18.30

250

06.00

400

22.00

200

Woke up at 08.00 next morning and voided 200 mL

  • Maximum voided volume 400 mL

  • Daytime frequency: 6 times (200, 200, 350, 400, 250, 200)

  • Night-time frequency: 4 times (200, 200, 300, 400)

  • Nocturia episodes: 3 times (200, 300, 400)

  • 24-hour urine volume: 200+350+400+200+200+200+200+300+400+200=2700

  • Nocturnal urine volume: 200+300+400+200=1100

  • NPI: 1100/2700 = 40.7% i.e. nocturia due to nocturnal polyuria

  • Ni: (200+300+400+200)/400 = 2.75 i.e. i.e. nocturia due to nocturnal polyuria

  • NBCi: 3-(2.75-1) = 1.25 i.e. nocturia is probably not due to reduced bladder capacity

3.4 Investigations

3.4.1 Biochemical blood tests

Simple measurement of urea and electrolytes is a common assessment which can provide useful information, since chronic kidney disease can influence urine output. In modern practice, the glomerular filtration rate (GFR) is often estimated and provides a slightly more accurate assessment of renal function. If the GFR is normal, it does not exclude a renal factor in nocturia—renal tubules are the main element controlling output, and renal tubular dysfunction (e.g. nephrogenic diabetes insipidus) is not necessarily associated with abnormal urea or electrolytes (which results from glomerular dysfunction). Electrolyte levels should be reviewed. Sodium levels can be particularly relevant, since a disrupted sodium level may reflect a natriuretic component of urine output. Furthermore, treatment with desmopressin requires a normal baseline level of sodium. Abnormal protein levels or calcium levels can influence urine output. Prostate cancer has been associated with nocturia, and prostate-specific antigen (PSA) measurement after counselling may be indicated.

3.4.2 Urinalysis

This can be done using a urine ‘dipstick’. If any abnormalities are found, then the urine can be sent for microscopy, culture, and sensitivity. Urinary tract infection or inflammation can contribute to increased voiding frequency, including nocturia. The presence of protein may trigger the need to assess renal function, and a spot test of protein-to-creatinine ratio can be informative for this.

3.4.3 Free flow rate and post-void residual

These assessments are conventionally undertaken in assessing LUTS. Impaired maximum flow rate points towards voiding dysfunction, and the presence of a substantial PVR is likely to increase urinary frequency, including during night time.

3.4.4 Ultrasound scan of the renal tract

An ultrasound scan to look at the renal structure and bladder emptying is not usually indicated, unless there is an abnormality on kidney function tests or urinalysis, or a significant post-void residual (PVR). Significant findings, such as renal masses, which are relevant to nocturia are unusual, but, if present, they must be identified and evaluated.

3.4.5 Urodynamic studies

These can have a role, if LUTS are clearly present in association with the patient’s nocturia and conservative and medical therapy have failed in resolving the symptoms. Conventional urodynamic assessment is unable to assess specific mechanisms underlying nocturia, since the patient is not in a suitable sleeping environment when undergoing urodynamic tests. Conclusions from urodynamic studies, such as detrusor overactivity or BOO, can therefore only be regarded as indirect at best.

3.4.6 Cystoscopic examination

Cystoscopy and biopsy to look for signs of interstitial cystitis, bladder stones, or bladder cancer are not usually indicated, unless there is an abnormality on previous investigations such as blood on urinalysis.

3.5 Specialized assessment

If a specific endocrine, nephrological, neurological, or cardiovascular problem is present, specialist referral may be warranted. Sleep studies and nocturnal oximetry can be used to screen for obstructive sleep apnoea and can be useful to identify parasomnias, restless leg syndrome, and other sleep abnormalities. The presence of such abnormalities is potentially important, since they may cause the patient to wake, following which the patient may become aware of the need to pass urine. This would make the nocturia the secondary, rather than the primary, cause of sleep disturbance.

3.6 Conclusions

The clinical assessment of nocturia is focused on identifying severity and bother, and establishing various potential underlying mechanisms in order to guide treatment selection. Key information with regard to the presence of LUTS, contributory habits, and systemic medical conditions must be obtained. The use of a screening questionnaire is the most time-efficient way to obtain much of this information. Examination should be directed toward potential contributory factors. The bladder diary (FVC) is an indispensable element of the assessment. Further specific tests are guided by individual circumstances.

References

1. Abrams P, et al. (2002). The standardisation of terminology of lower urinary tract function: report from the Standardisation Sub-committee of the International Continence Society. Neurourol Urodyn. 21:167–78.Find this resource:

2. Van Kerrebroeck P, et al. (2002). The standardization of terminology in nocturia: report from the Standardization Subcommittee of the International Continence Society. BJU Int. 90 Suppl 3:11–15.Find this resource:

3. Abrams P, Avery K, Gardener N, Donovan J (2006). The International Consultation on Incontinence Modular Questionnaire:. www.iciq.net J Urol. 175(3 Pt 1):1063–6; discussion 1066.Find this resource:

4. Abraham L, et al. (2004). Development and validation of a quality-of-life measure for men with nocturia. Urology. 63: 481–6.Find this resource:

5. Eid K, et al. (2014). Validation of the Urgency, Weak stream, Incomplete emptying, and Nocturia (UWIN) score compared with the American Urological Association Symptoms Score in assessing lower urinary tract symptoms in the clinical setting. Urology. 83:181–5.Find this resource:

6. Buysse DJ, et al. (1989). The Pittsburgh Sleep Quality Index: a new instrument for psychiatric practice and research. Psychiatry Res. 28:193–213.Find this resource:

7. Coyne KS, et al. (2009). The burden of lower urinary tract symptoms: evaluating the effect of LUTS on health-related quality of life, anxiety and depression: EpiLUTS. BJU Int. 103 Suppl 3:4–11.Find this resource:

8. Gulur DM, Mevcha AM, and Drake MJ (2011). Nocturia as a manifestation of systemic disease. BJU Int. 107:702–13.Find this resource:

9. Bright E, Drake MJ, and Abrams P (2011). Urinary diaries: evidence for the development and validation of diary content, format, and duration. Neurourol Urodyn. 30:348–52.Find this resource:

10. Cornu JN, et al. (2012). A contemporary assessment of nocturia: definition, epidemiology, pathophysiology, and management—a systematic review and meta-analysis. Eur Urol. 62:877–90.Find this resource:

11. Weiss JP (2006). Nocturia: ‘do the math’. J Urol. 175(3 Pt 2): S16–18.Find this resource:

12. Bright E, et al. (2014). Developing and validating the International Consultation on Incontinence Questionnaire bladder diary. Eur Urol. 66:294–300.Find this resource: