Adult Nocturnal Enuresis

Adult nocturnal enuresis is involuntary voiding during sleep in an adult (usually defined as age 18 and over), occurring at least once a month for 3 months.

Primary: persistent since childhood without a dry period of 6 months or more.

Secondary: recurrence after at least 6 months of dryness.

Prevalence about 0.5 to 2 percent of adults (about 1 in 100); with a family history in about 70 percent in the primary type.

Mechanisms: nocturnal polyuria from loss of the normal night time rise in antidiuretic hormone, detrusor overactivity or reduced functional bladder capacity at night, and impaired arousal from sleep (high arousal threshold).

Causes of secondary enuresis: obstructive sleep apnoea, uncontrolled diabetes mellitus (osmotic diuresis), diabetes insipidus, urinary tract infection, bladder outlet obstruction (men), overactive bladder, bladder stones or tumours, neurological disease (epilepsy with nocturnal seizures, multiple sclerosis, spinal cord disease, stroke, dementia), constipation, chronic kidney disease, heart failure, pregnancy, alcohol, sedatives, drugs (clozapine, risperidone, olanzapine, lithium, diuretics, SGLT2 inhibitors), psychological stress and abuse.

Impact: shame, social avoidance, depression, relationship difficulty, skin breakdown.

• Bed wetting, usually large volumes, often early in the night in nocturnal polyuria and deep sleep; small volumes at multiple times of night suggest detrusor overactivity.
• Ask about childhood history, family history, daytime urgency, frequency, incontinence, stream, nocturia, thirst, polyuria, snoring and witnessed apnoeas, daytime sleepiness, morning headaches, tongue biting, post-ictal confusion, alcohol, caffeine, evening fluid, constipation, medicines, psychiatric history, and sexual or physical abuse.
• Examination: BMI, blood pressure, oedema, abdomen (bladder, faecal loading), genitalia and rectal examination (prostate), lower limb neurology and perineal sensation, spine (spina bifida occulta, sacral dimple), fundi.
• Red flags: new onset secondary enuresis, haematuria, back pain, neurological deficit, loss of perineal sensation, weight loss, severe thirst, nocturnal seizures, daytime incontinence with retention.

• Frequency volume chart and enuresis diary for 2 weeks: wet nights, volumes, night time urine volume, first morning void, fluid intake.
• Urinalysis (glucose, protein, blood, leucocytes) and culture; bloods: glucose or HbA1c, urea, creatinine and eGFR, electrolytes, calcium, full blood count, thyroid function.
• Renal tract ultrasound with post-void residual; uroflowmetry; consider cystoscopy and urodynamics for failure of treatment, suspected outlet obstruction or neurogenic bladder.
• Sleep study for suspected sleep apnoea; EEG for suspected nocturnal seizures; spine and brain MRI if neurological signs.
• Nocturnal polyuria is defined as night urine volume above 33 percent of 24 hour output in older adults (above 20 percent in young adults).

• Treat reversible causes: continuous positive airway pressure for sleep apnoea, diabetes control, infection, constipation, drug review (switch or reduce offending agents), manage obstruction.

• Behavioural: limit fluid intake in the 2 to 3 hours before bed, avoid caffeine and alcohol in the evening, void just before sleeping (double void), regular daytime voiding, protective bedding, waterproof mattress covers, barrier cream.

• Enuresis alarm (wet sensor alarm with sound or vibration): worn nightly for at least 6 to 8 weeks and continued until 14 consecutive dry nights; effective in motivated patients (about 60 to 70 percent initial success) with a lower relapse than drugs; reinforce with a partner or carer to help waking.

• Desmopressin (antidiuretic) for nocturnal polyuria:

  • Desmopressin oral lyophilisate (melt) 120 micrograms sublingually at bedtime, increased to 240 micrograms if inadequate response after 1 to 2 weeks; or tablets 200 micrograms at bedtime, increased to 400 micrograms (use in adult enuresis is off label). The nocturia specific melt formulation is 25 micrograms (women) or 50 micrograms (men).

  • Restrict fluids from 1 hour before to 8 hours after the dose. Check serum sodium at baseline, after 3 days and at 1 month; stop if sodium is below 130 mmol/L. Contraindications: heart failure, renal impairment (eGFR under 50 mL/min), hyponatraemia, syndrome of inappropriate antidiuretic hormone secretion, polydipsia, diuretic use, uncontrolled hypertension, and caution above 65 years.

  • Intermittent use for sleepovers or travel is acceptable.

• Detrusor overactivity: solifenacin 5 mg orally once daily (increase to 10 mg), or oxybutynin 5 mg at bedtime (modified release 5 to 10 mg), or mirabegron 50 mg orally once daily; add to desmopressin or alarm when needed; avoid anticholinergics in dementia or the elderly with cognitive concerns.

• Tricyclic antidepressant: imipramine 25 mg at night, increased to 50 to 75 mg (second line; cardiac toxicity, anticholinergic effects, overdose danger).

• Combined alarm plus desmopressin for refractory cases. Psychological support and cognitive behavioural therapy for distress.

• Refer: new onset secondary enuresis, neurological features, haematuria, failure of alarm and drugs, suspected abuse, suspected structural disease.

• Review at 4 to 6 weeks.