Nocturia may present in isolation or it may be a manifestation of other urinary disturbances such as polyuria or frequency. Surprisingly, in older age groups, it is as common in women as men. Occasional nocturia is, of course, quite normal – the symptom should only be viewed as pathological when it causes disruption or distress.

Published: 2nd August 2022 | Updated: 15th August 2022

Differential diagnosis

Common Diagnoses

  • Age Related (in Part Caused by A Reduction in Bladder Capacity)
  • Excess Fluid Intake at Bed Time (Especially Alcohol)
  • Any Cause of Swollen Ankles (the Recumbent Posture Redistributes the Fluid Load At Night) – See ‘Swollen Ankles’
  • Cystitis
  • Luts in Men, Secondary to Benign Prostatic Enlargement

Occasional Diagnoses

  • Overactive Bladder Syndrome
  • Lower Urinary Tract Obstruction (other Than Prostate Problems)
  • Any other Cause of Urinary Frequency (See ‘Frequency’)
  • Diabetes Mellitus
  • Any other Cause of Polyuria (See ‘Excessive Urination’)
  • Sleep Apnoea (Causes Overproduction of Urine)

Rare Diagnoses

  • Anxiety
  • Drug Side Effect (Rare because Drugs Likely to Cause Diuresis Are Usually Taken in the Morning)
  • Diabetes Insipidus

Ready reckoner

Key distinguishing features of the most common diagnoses

Age RelatedExcess Fluid IntakeSwollen AnklesCystitisLUTS
Daytime Ankle OedemaPossibleNoYesNoNo
Daytime FrequencyPossibleNoNoYesPossible
Poor Urinary FlowNoNoNoNoYes
Long-Term ProblemYesPossibleYesNoYes

Possible investigations

Likely: Urinalysis, MSU, urinary frequency volume chart.

Possible: Blood sugar/HbA1c, PSA.

Small Print: Cystoscopy, urodynamic studies, ultrasound, water deprivation test.

  • Urinalysis: Protein, nitrites, leucocytes and possible haematuria in infection; glucose in diabetes; specific gravity very low in diabetes insipidus.
  • MSU: To confirm infection and identify pathogen.
  • Urinary frequency volume chart: To help distinguish nocturnal polyuria (increased urine production at night) from reduced bladder storage capacity.
  • Blood sugar/HbA1c: To confirm diabetes mellitus.
  • PSA: Pros and cons of this test may be discussed if assessment raises the possibility of prostate cancer.
  • Specialist tests include: Cystoscopy and ultrasound (for lower urinary tract obstruction), urodynamic studies (for unstable bladder) and water deprivation test (for diabetes insipidus).

Top Tips

  • In the elderly, the cause is often multifactorial.
  • The effects: Such as disturbed sleep, a disrupted household, exhaustion and occasional incontinence – may be more important to the patient than the specific diagnosis.
  • Swollen ankles: Of any aetiology – are frequently overlooked as an underlying cause
  • Nocturia may just be a manifestation (albeit the most distressing) of polyuria or urinary frequency. Focus your approach on the underlying problem.

Red Flags

  • Exclude diabetes – but remember that it is not the only cause of polyuria, nocturia and thirst.
  • A habitual ‘nightcap’ may be the cause of nocturia – and may be a pointer to an underlying alcohol problem, especially in solitary elderly males.
Report errors, or incorrect content by clicking here.
Website disclaimer

Pulse Reference is based on the best-selling book Symptom Sorter.

The experts behind Pulse Reference are Dr Keith Hopcroft who is the co-author of Symptom Sorter, a GP in Essex and Pulse’s editorial advisor and Dr Poppy Freeman, a GP in Camden and also a clinical advisor to Pulse.

This website is for clinical guidance only and cannot give definitive diagnostic information. Practitioners should work within the limits of their individual professional practice, seek guidance when necessary and refer appropriately.