Signs and Symptoms

The causes of nocturia can be divided into the following categories:

• Global polyuria - persistently raised urine output over a 24-hour period. Commonly caused by primary polydipsia or uncontrolled diabetes mellitus

• Nocturnal polyuria - increased urine production at night, typically defined as more than 1/3 of the 24-hour urine output voided at night. Causes include:
  • changes in anti-diuretic hormone (ADH) with age;
  • fluid shift as a result of peripheral oedema redistributing when recumbent;
  • changes in Atrial Natriuretic Peptide (ANP) linked with age or obstructive sleep apnoea (OSA), and Brain Natriuretic Peptide (BNP) due to heart failure

• Bladder storage disorders - any structural or functional pathology that affects the reservoir capacity of the bladder e.g. bladder outflow obstruction, overactive bladder, bladder tumour, bladder stone, external compression, neurogenic bladder dysfunction. This will typically cause frequent small volume voids
• Sleep disorders - patients that wake during the night often void whether or not the reason for waking was the need to void

History and Examination

History

• Presence of Lower Urinary Tract Symptoms (LUTS): LUTS Clinical Referral Guideline and International Prostate Symptom Score (IPSS)
  • Voiding/obstructive LUTS - hesitancy, weak stream, incomplete emptying
  • Storage LUTS - frequency, urgency
• Incontinence
• Nocturnal enuresis
• Haematuria
• Fluid intake, alcohol and caffeine consumption
• Past medical history, in particular: heart failure, Chronic Kidney Disease (CKD), low albumin, diabetes, obstructive sleep apnoea, gastro-oesophageal reflux disease (GORD)
• Medication history, in particular: diuretics, lithium

Examination

• Blood pressure
• Weight
• Cardiovascular examination - signs of heart failure
• Abdominal examination – to exclude chronic retention
• Lower limbs – signs of pedal oedema
• Digital rectal examination

• Haematuria
• Incontinence particularly nocturnal enuresis (the latter is suggestive of high pressure chronic retention)
• Back pain
• Unexplained weight loss
• Abnormal digital rectal examination (DRE)
• Any concerns over prostate or bladder cancer

• Urinalysis
• Frequency volume chart – a voiding diary for a 24-hour period. This will guide the differentiation between global polyuria, nocturnal polyuria or bladder storage disorder
• Blood tests – Urea and Electrolytes (UEs), Glomerular Filtration Rate (GFR), HbA1c/glucose, Calcium, Serum Osmolality if global polyuria (to exclude diabetes insipidus), Prostate Specific Antigen (PSA) if indicated, BNP if suspicion of heart failure
• Ultrasound scan KUB (USS KUB) if indicated, e.g. if abnormal UEs
• Polysomnography – for suspected obstructive sleep apnoea (if meets referral criteria link to Sleep CRG)

Management of nocturia should be directed at the underlying cause. There are several lifestyle modifications which can help to improve nocturia:

• avoid drinking caffeine and alcohol in the evening
• limit fluid intake around 3 hours before bedtime
• evening leg elevation if pedal oedema
• timing of medications – moving diuretics to mid-afternoon, administer calcium channel blockers in the morning
• ensure good sleeping conditions e.g. lighting, temperature, reducing daytime naps

The varied causes of nocturia make its management challenging. Specific management for each subdivision is given below:

Global polyuria

• Primary polydipsia can be managed by fluid restriction
• Poorly controlled diabetes and diabetes insipidus could benefit from endocrinology assessment

Nocturnal polyuria

• Treating the underlying cause:
  • Heart Failure (refer to Formulary Chapter 2)
  • Obstructive Sleep Apnoea

• Mid-afternoon diuretics (refer to Formulary Guidance: 2.2.2 Loop diuretics) can be used cautiously in selected cases, to attempt to off load fluid before night time to reduce urine output overnight due to fluid redistribution. If already on diuretics, consider moving a morning dose to a mid-afternoon dose
• Desmopressin is a synthetic antidiuretic hormone (ADH) analogue thought to replace the circadian rhythm in the secretion of ADH. Desmopressin is now licenced for specialist use in the over 65s and can be used at a low dose in the evenings to attempt to reduce overnight urine output (refer to Formulary Guidance 6.5.2 Posterior pituitary hormones and antagonists)

Of note, Desmopressin should be used with caution in patients with conditions potentially causing fluid or electrolyte imbalance due to the risk of hyponatraemia and fluid overload.

Bladder storage disorders

• These patients may require urological assessment
• Further investigations may include uroflowmetry, post void residual measurement, urodynamics or cystoscopy
• Voiding/obstructive LUTS can be improved with drug treatment – refer to Formulary:
  • 7.4.1 Drugs for urinary retention
  • 7.4.2 Drugs for urinary frequency, enuresis, and incontinence
• Surgical treatment in the form of Trans-Urethral Resection of the Prostate (TURP) (or similar) can be beneficial in selected patients with predominant bladder outflow obstruction

If symptoms persist despite following the suggested management for the underlying cause, then consider referral to the appropriate team (as per the management section).

Please include the results of relevant investigations and a list of management trialled.

Please note these referrals are subject to Pre-choice Triage.

Referral Instructions

Bladder storage disorders

e-Referral Service Selection:

• Specialty: Urology
• Clinic Type: Not Otherwise Specified
• Service: DRSS-South Devon & Torbay-Urology - Devon ICB - 15N

Referral Form

DRSS Referral Form

Evidence

Nocturia A guide to assessment and management

Pathway Group

This guideline has been signed off on behalf of the NHS Devon.

Publication date: July 2020