Nocturia

1. See Also
   1. Urinary Frequency
   2. Polyuria
2. Definitions
   1. Nocturia
      1. Frequent Urination at night (more than once)
3. Mechanism
   1. Urine Volumes are typically reduced at night via diurnal rhythm
   2. 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
4. Causes
   1. All causes of Polyuria also cause Nocturia
      1. Diabetes Mellitus
      2. Diabetes Insipidus
      3. Primary Polydipsia (e.g. water Intoxication)
   2. Decreased Bladder capacity (may be due to inflammation or irritability)
      1. Urinary Tract Infection
      2. Bladder Tumor
      3. Urinary tract stone
   3. 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
   4. Bladder outflow obstruction
      1. Benign Prostatic Hyperplasia
      2. Urethral stricture
      3. Urinary tract stone
      4. Pelvic tumor
   5. Other causes
      1. Sleep Apnea
5. Management
   1. Identify and treat underlying causes
      1. Benign Prostatic Hyperplasia
      2. Diabetes Mellitus
      3. Diabetes Insipidus
      4. Overactive Bladder
      5. Obstructive Sleep Apnea
   2. Employ simple strategies
      1. Dose Loop Diuretics earlier in the day
      2. Redistribute edema during the daytime (e.g. Compression Socks, leg elevation)
   3. Medications (not recommended)
      1. Low dose Desmopressin (Noctiva)
         1. Expensive, marginal efficacy, risk of Hyponatremia (requires Sodium monitoring)
6. References
   1. (2018) Presc Lett 25(5): 27
   2. Coe in Wilson (1991) Harrison's Internal Medicine, 12th ed, McGraw Hill, p. 275