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Nocturia: Causes, Evaluation, and Management of Nighttime Urination

Nocturia is the need to wake from sleep to void urine (≥1 time/night). It is a symptom, not a disease, affecting >50% of adults >60 years and significantly impairing sleep quality, daytime function, and fall risk.

Pathophysiologic Categories

MechanismKey CausesClinical Clues
Global polyuria (>40 mL/kg/24h)Diabetes mellitus (osmotic), diabetes insipidus, primary polydipsia, IV fluidsLarge volume voids day & night; check glucose, Na⁺, urine osmolality
Nocturnal polyuria (>33% 24h volume at night)Heart failure, CKD, OSA, venous edema, meds (diuretics at night), aging (↓ADH)Normal daytime volume; large night volumes; fluid shift on lying down
Reduced bladder capacityOAB, BOO (BPH, stricture), cystitis, radiation cystitis, neurogenic bladderSmall volumes, urgency, frequency day & night
Sleep disordersOSA, insomnia, RLS, circadian disruptionAwaken for other reasons, then void "while up"

Evaluation

  1. Voiding diary (3 days): Volumes, times, fluid intake — gold standard for phenotyping.
  2. History: Meds (diuretics, α-blockers, SSRIs), cardiac/renal/neurologic history, sleep symptoms.
  3. Exam: Abdomen, GU, neuro (saddle sensation, anal tone), DRE (prostate).
  4. Labs: UA, culture, glucose/HbA1c, creatinine/eGFR, Na⁺, Ca²⁺, PSA (if male).
  5. PVR (post-void residual): Ultrasound or catheter.
  6. Urodynamics: If neurogenic, refractory, or pre-surgical.

Management (Stepwise)

  • Behavioral: Fluid restriction after 6 PM, caffeine/alcohol reduction, leg elevation (edema), compression stockings, timed voiding, sleep hygiene.
  • Medication timing: Diuretics → morning; desmopressin (0.1–0.2 mg PO/SL at bedtime) for nocturnal polyuria (monitor Na⁺).
  • OAB/BOO: Antimuscarinics, β3-agonists (mirabegron), α-blockers, 5-ARIs.
  • OSA: CPAP → reduces ANP → less nocturnal polyuria.
  • Surgical: TURP/HoLEP (BPH), sling (SUI), sacral neuromodulation (refractory OAB).

Special Populations

  • Elderly: Fall risk → night lights, commode, review fall-risk meds.
  • Pregnancy: Mechanical + hormonal; reassure, limit evening fluids.
  • Children: Enuresis vs. nocturia — different pathways.

Nocturia is treatable—phenotype with a voiding diary, target the mechanism, and restore sleep.

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