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Nocturia

Waking to void once or more during sleep

  • Primary nocturia – waking from sleep exclusive because of the need to void
  • Secondary nocturia – voiding at night whilst awake for other reasons (or ‘convenience’)

 

Nocturia 2x or more is associated with significant impacts of quality of life, as well as physical health:

  • Sleep deprivation, which is linked to depression and metabolic syndrome
  • Falls
  • Fractures
  • Nocturia carries an increased risk of mortality of meta-analyses

 

Epidemiology

Proportional increase with age.

Up to 60 % of those older than 70 have nocturia 2 x or more.

Younger women more likely to have nocturia than younger men, but this trend reverses with ageing.

 

 

Assessment

  • Quantify and characterise nocturia
    • Urgency, duration of symptoms, incontinence
    • Primary vs secondary
  • Daytime LUTS
    • Compare to night
    • Concomitant storage/OAB symptoms
  • Medical history
    • Heart failure (peripheral oedema)
    • OSA
    • DM
    • Depression
  • Medications
    • Diuretics (and timing), lithium, SSRI
  • Surgical history
    • Urological surgery, other pelvic surgery
  • Social / fluid intake
    • Caffeine
    • Nighttime fluid intake
    • Sleep disturbances
  • Level of bother

 

Examination – general examination including BMI/habitus/frailty, pelvic exam with DRE, look for peripheral oedema, mobility, postural blood pressures

 

Investigations

  • Urinalysis and MCS
  • Bloods – renal function, PSA if appropriate, electrolytes, glucose/HbA1c
  • Urine flow rate and residual volume
  • Bladder diary
  • Ultrasound KUB

 

Interpreting the bladder diary

Minimum of 2, preferably 3 separate 24 hour periods.

Time volume chart, with additional info regarding urgency, incontinence, fluid intake.

Information derived includes:

  • Daytime and night time frequency
  • Total voided volume in 24 hours
  • Maximum voided volume (estimate of functional capacity)
  • Nocturia polyuria index
    • % of urine produced during night
    • Noctural urine volume / 24 hour urine volume
    • Nocturnal volume includes voids after retiring, and first void on waking

 

With bladder diary, can characterise to:

  1. Nocturnal polyuria
  2. Global polyuria
  3. Diminished bladder capacity (either nocturnally or globally)
  4. Mixed

 

Nocturnal polyuria

Various definitions – generally the excess production of urine at night relative to daytime

  • Nocturnal urine output > 33 % of total daily urine output (or > 20 % in younger people)
  • Alternative definitions consider > 6.4 mL/kg nocturnal urine output, or > 54 mL / hr nocturnal output

 

Nocturnal polyuria becomes much more prevalent with ageing due to differences in circadian rhythm guided urine production. Normal ADH production is diurnal with high levels at night reducing urine output; this is lost with ageing.

 

How does sleep apnoea cause nocturia?

  • Increased airway pressures lead to hypoxia and pulmonary vasoconstriction -> increased right atrial pressure
  • Causes increased release of ANP
  • ANP causes increased sodium and water excretion and diuresis.
  • Treating OSA with CPAP has been shown to definitively reduce number of nocturia episodes.

 

Treatment of nocturia

Conservative:

  • Reduce night-time fluid and caffeine
  • Elevate legs in evening
  • Avoid alcohol
  • Optimise medication timing
  • Optimise sleep
  • Regular exercise can cause deeper sleep
  • Psychological optimisation and removal of stressors

Urological:

  • Treat outlet obstruction
  • Treat overactive bladder
  • Treat other urological triggers (stones, cancer)

Other medical options:

  • CPAP for OSA
  • Lasix in mid afternoon
  • Melatonin for sleep / other sleeping tablets

 

Desmopressin

Proven in multiple RCTs to improve nocturia.

Synthetic analogue of ADH – stimulates V2 receptors to cause translocation of aquaporins in collecting duct, increasing water reabsorption and reducing nocturnal urine volume

Women have lower V2 receptor concentration and need lower doses.

 

Indicated for – adults with idiopathic nocturnal polyuria who wake more than twice per night and have not responded to lifestyle measures

25 ug for women, 50 ug for men at bedtime.

Contra-indicated in:

  • eGFR < 50
  • Heart failure
  • Caution in people over 65

Main concern is hyponatraemia

  • Check Na at baseline, 1 week, 1 month, then every 3 – 6 months or if clinical concerns
  • No oral intake after taking to avoid water intoxication