Nocturia

Urine Volumes are typically reduced at night via diurnal rhythm
Nocturia occurs when urine formed exceeds Bladder capacity
1. Decreased Bladder capacity
2. Decreased renal concentrating function
3. High Sodium excretion or other solute diuresis

All causes of Polyuria also cause Nocturia
1. Diabetes Mellitus
2. Diabetes Insipidus
3. Primary Polydipsia (e.g. Water Intoxication)
Decreased Bladder capacity (may be due to inflammation or irritability)
1. Urinary Tract Infection
2. Bladder Tumor
3. Urinary tract stone
Edematous State fluid redistributes at night into dependent positions and then intravascularly mobilized
1. Congestive Heart Failure
2. Nephrotic Syndrome
3. Hepatic Cirrhosis with Ascites
4. Venous Insufficiency
Bladder outflow obstruction or Urinary Retention
1. See Medication Causes of Urinary Retention
2. Benign Prostatic Hyperplasia
3. Urethral Stricture
4. Urinary tract stone
5. Pelvic tumor
Other causes
1. Obstructive Sleep Apnea

Urinary symptoms
1. Number of night awakenings to urinate
2. First Nocturia episode within 3 hours of going to sleep\
3. Daytime urine frequency
4. Urine urgency
5. Urinary Tract Infection symptoms
6. Incomplete Bladder emptying, double voiding or decreased urinary stream
Nocturia degree of bothersomeness
1. Less than 5 hours of sleep per night
2. Daytime Somnolence
3. Associated falls or injuries
Past medical history
1. Diabetes Mellitus (esp. with poor control)
2. Congestive Heart Failure
3. Hypertension
4. Chronic Kidney Disease
5. Obstructive Sleep Apnea
  1. See STOP-Bang Questionnaire
6. Benign Prostatic Hyperplasia
  1. See Benign Prostatic Hyperplasia Symptom Index
Medications
1. Diuretics
2. Timing and amount of fluid intake
3. Caffeine
4. Alcohol

Urinalysis
Fingerstick or Blood Glucose (and consider Hemoglobin A1C)
Post-void residual Urine Volume (via Ultrasound, Bladder scan or urine catheterization)

Evaluate urine frequency and volume for those without underlying cause
1. Diary for 2-3 days of urine frequency and volume logs (including nighttime voids)
Nocturnal Polyuria
1. Diagnosis
  1. Older patients: Nocturnal Urine Volume >33% of total Urine Output in 24 hours
  2. Younger patients: Nocturnal Urine Volume >20% of total Urine Output in 24 hours
2. Management
  1. Exclude underlying Edematous States (e.g. CHF) and causative medications and habits
  2. Consider Low dose Desmopressin (Noctiva)
    1. Expensive, marginal efficacy, risk of Hyponatremia (requires Sodium monitoring)
    2. See Desmopressin for contraindications and Drug Interactions
Men with suspected Benign Prostatic Hyperplasia (BPH)
1. Consider Alpha Adrenergic Receptor Blocker (e.g. Tamsulosin)
2. Consider urology Consultation
Women with suspected Overactive Bladder (Urge Incontinence)
1. Diagnosis
  1. Day and night frequency, urine urgency, and Urge Incontinence
2. Management
  1. Consider Bladder Antispasmodics (e.g. Oxybutynin, Tolterodine)
  2. Consider Atrophic Vaginitis management (Menopause)
  3. Consider urology referral for advanced treatments (e.g. Detrussor Muscle Botulinum Toxin Injection)