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What is Nocturia? Causes of Frequent Urination at Night

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Nocturia is the term for urinary frequency resulting in waking up at night (awaking from sleep) in order to pass urine. The volume of urine is not significantly large as is the case with polyuria (passing >3 litres of urine in a 24 hour period). With nocturia, the total daily urine output is normal or even less than the normal volume. In the event that there is a large urine volume output in a day (>3 liters per day), then the causes of polyuria should first be considered.

Usually there is constant urging which is not alleviated by passing urine. A patient will often report that the bladder does not feel like it is empty even after urination. This feeling, which is known as tenesmus, can be quite distressing and despite the best efforts to force out as much urine as possible, the sensation persists. Nocturia does not usually occur in isolation – often the frequent urination is also evident during the waking hours (i.e. during the day).

Many patients suffering with nocturia may also report urinary incontinence – either the solitary incident or recurrent episodes.

Causes of Nocturia

Nocturia may be due to the consumption of :

  • Drugs (iatrogenic) like diuretics.
  • Foods and drinks with a diuretic action (example : tea, coffee, alcohol).
  • Excessive intake of fluids throughout the day or prior to falling asleep.

The above causes should be excluded before considering any pathological causes.

Psychogenic causes of nocturia may be related to psychogenic polydipsia (perception of unquenchable thirst), anxiety, depression or insomnia and other sleep disturbances. Pregnancy is another common non-pathological cause of nocturia, especially in the latter stages.

Most pathological causes of nocturia involve some degree of obstruction of the lower genotourinary system or are related to kidney disorders.

  • Urinary tract infections (UTI’s)
  • Urinary stones
  • Urethral stricture (narrowing of the urethra)
  • Causes of urinary incontinence
  • Causes of polyuria – diabetes mellitus must always be considered in frequent urination due to the incidence of this endocrine disorder.
  • Benign prostatic hyperplasia (BPH)
  • Prostatitis
  • Prostate cancer
  • Cystitis
  • Cystocele
  • Spinal cord injury/lesion
  • Chronic kidney diseases
  • Age-related changes of the bladder and urethra

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Article reviewed by Dr. Greg. Last updated on April 12, 2011