BJU International (1999), 84, Suppl. 1, 33–35

Nocturia: current knowledge and future directionsA. MATTIASSONLund University Hospital, Department of Urology, Lund, Sweden

Keywords Nocturia, arginine vasopressin, atrial natriuretic peptide, pharmacology, prevalence

Table 1 Factors common to day- and night-time voiding problemsWhat is nocturia?

Infection or urinary tract stonesNocturia (literally ‘voiding at night’) has no specificBPH with/without detrusor instability

clinical definition; however, by examining nocturia from Detrusor instability (without prostate disease)several perspectives, it may be possible to determine Psychological (stress, anxiety)more exactly what constitutes nocturia. Structural: small bladder, postradiotherapy or repeat surgery, after

infection by tuberculosis, malignancyFluid factors: fluid intake, diabetes mellitus, diabetes insipidus

Day- and night-time micturition Drugs: diuretics, calcium-blockers, NSAIDs, xanthines, caCeineAgeingDiCerences exist between day- and night-time urinary

tract problems. Incontinence is a common problem inelderly people, especially women. Stress incontinenceoccurs almost exclusively during the day, but urge

Bothersomenessincontinence can occur both during the day and atnight, and this can seriously aCect the quality of life [1]. Some people find voiding at night causes them no

problem while the quality of life of others is seriouslyObstructions in the urinary tract primarily cause prob-lems at night and these tend to appear before any aCected by relatively few nocturnal voids. Whether noc-

turia could be considered to be ‘inconvenient’ voiding atdaytime problems [2]. Urinary infections and variousmedications can aCect both day- and night-time mictur- night or not, it is important to examine the relationship

between urine production, eCective bladder storageition. In contrast, volume problems occur predominantlyat night. Some factors are common to both daytime capacity and the hours of sleep that an individual needs

to be able perform eCectively during the day. Otherand night-time micturition, and these are detailed inTable 1. factors that should be considered are the ability to return

to sleep and how bothersome it is to get up at night tovoid. Together these factors contribute to the overall

High- and low-volume frequencyquality of life of the individual.

People who void at night can be divided into those withlow-and those with high-volume frequency. The former

Defining nocturiaincludes those who have a high frequency of awakeningbut their total nocturnal urine production is normal or The need for an agreed definition of nocturia is para-

mount, but it was clear from the lively discussions innot excessive. The category includes people with sleepdisorders, other conditions that result in awakening, e.g. the meeting that a consensus on a definition of nocturia

is far from being reached. Some feel that nocturia shouldcardiac problems or pain, or external factors (e.g. noise,children or partners waking), or occupational factors be defined as any episode of ‘getting up to void at night’,

whereas others consider it should only include thosethat cause awakening at night. Patients with high-volume frequency produce more urine during the hours who get up more than once a night. Additionally,

subjective factors such as bothersomeness may be con-of sleep than they do during the remainder of the 24 h.Factors that may influence high-volume nocturia include sidered important enough to be part of a definition,

which could comprise a description of the number ofarginine vasopressin production by the pituitary, renalcauses such as nephrogenic diabetes insipidus, atrial voids and a score of bother. Other factors that must also

be considered are the significant cultural diCerencesnatriuretic peptide and its eCects on sodium metab-olism, fluid intake (especially alcohol), pharmacological that exist among countries, particularly in terms of

the perception of symptoms and bothersomeness,therapies and congestive cardiac failure.

33© 1999 BJU International

34 A. MATTIASSON

health-seeking behaviour, access to medical care and Urinary output is influenced by fluid intake; it isrecognized that some people alter their lifestyle by sever-treatments available. One major problem with any defi-

nition of nocturia will be the diCerentiation of those who ely restricting their fluid intake to reduce the frequencyof nocturia. It is important to consider this when diagnos-awaken because of a poor sleep pattern and then get up

to void, from those who awaken because of nocturia ing possible causes of nocturia.and who also have a poor sleep pattern (if these peopleare not considered to have nocturia).

Key questions

Several important questions that require furtherWhat is normal?

research are:(i) What is normal?Waking once at night to void is extremely common

behaviour and may be a normal part of ageing. However, (ii) How much nocturia is caused by the normal ageingprocess? (i.e. physiological decline rather than pathologi-it is highly questionable whether this should de defined

as normal, even though it may be clinically insignificant. cal processes).(iii) How does the bladder function at night?One analogy is that although prostate cancer is common

in men over the age of 70 years, it cannot be considered (iv) Does the functional bladder capacity (FBC) changefrom day to day? (i.e is the FBC suBciently consistentnormal. Moreover, what an individual perceives to be

normal is an important factor in considering what is that a value from one 24-h voiding diary is suBcient,or would it be better to use a mean from several days?)‘normal’. However, a patient’s perception of what is

normal and/or bothersome can be influenced by aware- (v) At what level of nocturia should the patientundergo further investigation and then treatment?ness of an available treatment, as in the case of hormone-

replacement therapy during and after the menopause. (vi) What causes awakening at night to void in patientswith nocturia? Do concomitant conditions (e.g. cardiacproblems) cause patients to awaken or is their nocturia

Factors aVecting diagnosis and treatmentthe primary reason for awakening? Are there two kindsof aCerent activity in the bladder; one where there is noDuring discussions it was evident that certain factors

would aCect the diagnosis and treatment, but exactly motor activity and one secondary to bladder contractionsas a result of detrusor overactivity?where these would fit into a diagnostic algorithm is not

yet known. There are many causes of nocturia and each (vii) Is the bothersomeness of nocturia related to thetiming of voiding at night?should be carefully classified as to importance, bother-

someness and treatment possibilities, especially in theelderly. Long-term data on nocturia are needed, e.g. does

Recommendations for future studiesit become more frequent over time in an individual?Voiding diaries are simple and inexpensive tools that A structured interview or questionnaire study for people

of diCerent age groups is needed to understand moreprovide valuable information about nocturia. However,the minimum number of days required to obtain reliable fully what level of nocturia is normal, taking into

account how bothersome the condition is. The drawbackand accurate information from a voiding diary isunknown. Recent data suggest that a 24-h or 48-h diary of using only one fixed value to define ‘normality’, e.g.

one void at night, is that it does not take into consider-is insuBcient, but that a 72-h diary is highly reproduc-ible; further studies are needed. Moreover, there may be ation that getting up once may be bothersome for some

patients and not others.diCerences between diaries kept during weekdays orweekends. Large-scale prospective longitudinal epidemiological

studies are needed to determine the prevalence of noctu-There is no doubt that a 24-h urine collection isuseful, but this needs to be standardized. It was suggested ria in the general population and how it aCects people’s

lives. Recognition of the true prevalence of nocturia andthat urine collection should be divided into three 8-hgroups to more correctly assess the volume and composi- its consequences may provide a new perspective on how

satisfactory sleep may be. As there are many possibletion of the nocturnal voids. Additionally, patients shouldbe divided into those with solute or water diuresis. Such causes of nocturia, further studies should be made to

determine the prevalence of nocturia of diCerent aeti-measures may help to classify patients into subgroupswhich can be targeted for specific therapies. It is import- ologies. Moreover, in older people, where nocturia may be

associated with multiple comorbidities, studies areant to be able to identify and distinguish those groupsof patients who would respond to certain drugs such as needed to determine the relative contribution of each

condition to nocturia. Such information will help in thedesmopressin, and those in whom such treatmentsshould be avoided. planning and design of interventional studies.

© 1999 BJU International 84, Suppl. 1, 33–35

NOCTURIA: CURRENT KNOWL EDGE AND FUTURE DIRECTIONS 35

Studies in sleep laboratories are needed to further Further information on fluid intake, timing and habitsin diCerent age-groups is needed to fully understandunderstand the relationship between sleep and nocturia.

There are many questions that remain to be answered: urinary output. Such information can be included invoiding diaries. Studies should determine the frequencyis there any correlation between the bothersomeness

of nocturia and how quickly an individual can return of lifestyle adjustments among people with nocturia. Inaddition, it was suggested that standardization of noctu-to sleep after awakening; is the bothersomeness of

nocturia solely caused by sleep disturbances; are ria indices on the basis of standardized fluid intake wouldbe useful. Suggestions of diCerent indices to determinechanges in bladder sensation awareness related to the

quality or depth of sleep; do medications that assist the cause of nocturia need further evaluation [3].Such measurements could be useful, but they must besleep (e.g. hypnotics, anxiolytics) alter the pattern of

nocturia; do sleep disturbances per se influence detrusor validated in many patients before they can be usedroutinely.function?

It is clear that further understanding of the physiology Studies are needed to compare novel treatments fornocturnal urine overproduction, e.g. desmopressin, withand mechanisms of bladder reactivity during the night

are needed. It was suggested that combined urodynamic more conventional therapies, e.g. support stockings (withor without diuretics like frusemide) in patients whoand sleep studies in small well-defined groups of patients

may provide the most valuable information. Such studies have oedema.could answer several questions about bladder capacityand function in relation to sleep patterns and timings

Summaryof awakening. For example, does the bladder becomeunstable during rapid-eye movement (REM) sleep? The discussion provided some valuable questions and

recommendations for future studies. Perhaps mostCombined urodynamic and sleep studies could determinewhether a primary awakening process of sleep disturb- importantly, it is evident that nocturia is a bothersome

condition that should be fully defined so that it may beance is causing nocturia episodes or whether unstabledetrusor contractions are triggering aCerent messages to diagnosed and treated. It is hoped that some of the

recommendations for future studies will enable thesethe CNS to arise and void.A study providing information on the timing of noctu- goals to be realized soon.

ria may be helpful and easy to perform. There are dataon the timing of episodes of enuresis in children, but Referencessimilar data on the timing of nocturia are lacking. For

1 Donovan J, Naughton M, Gotoh M et al. Symptom andexample, if a patient has nocturia once a night, is it quality of life assessment. In Abrams P, Khoury A, Wein AJ,typically at 02500 hours or 06500 hours? Is the timing eds. International Consultation on Incontinence, 1998: 295–331diCerent in somebody who has nocturia two or three 2 De la Rosette JJMCH, Witjes WPJ, Schafer W et al.times a night? Relationships between lower urinary tract symptoms and

bladder outlet obstruction: results from the ICS-BPH study.A longitudinal study is needed of the natural historyNeurourol Urodyn 1998; 17: 99–108of nocturia in a cohort of men and women; a group of

3 Weiss JP, Stember DS, Chaikin DC, Blaivas JG. Evaluation ofpeople could be followed from normality through advanc-the etiology of nocturia in men. The nocturia and nocturnaling age to determine any changes in hormonal factorsbladder capacity indices. Neurourol Urodyn 1999; in presssuch as vasopressin that relate to the development of

nocturia. Additionally, an international database of themedications and comorbidities of elderly people with Authornocturia may reveal further information about the A. Mattiasson, Lund University Hospital, Department of

Urology, Lund, Sweden.disease.

© 1999 BJU International 84, Suppl. 1, 33–35