Nocturia

Background

Nocturia: the need for frequent urination at night; usually defined as waking more than 2 times at night to urinate. This is a type of urinary frequency.

 

Causes

There are 3 general causes of nocturia.

  1. Lower urinary tract (bladder) dysfunction
  2. High nighttime urine output
  3. Insomnia

 

It is important to note that not all nocturia is secondary to urinary tract dysfunction. In fact, most nocturia is not the result of lower urinary tract/bladder dysfunction.

 

Lower Urinary Tract Dysfunction

There are 3 basic mechanisms of nocturia related to bladder function:

  1. Small bladder capacity: this is actually quite an UNcommon cause
  2. Bladder spasticity: the bladder contracts when it should be 'quiet'
  3. Abnormal bladder sensitivity: the bladder sends a signal that it is full, even when it has not reached capacity

These mechanisms can result from a large number of causes including:

  1. Outflow obstruction; e.g. BPH
  2. Neurological problems with the bladder
  3. Over-active bladder
  4. Bladder infections
High Nighttime Urine Output

An important function of the bladder is to wake you up when it is full (i.e. has reached it's capacity). This is a learned behavior which is typically taught during toilet training. If people did not awaken when the bladder was full, then they would wet the bed. Bedwetting in adulthood is considered abnormal and is known as 'enuresis'.

 

The bladder is doing it's job if it wakes you when it is full. It is easy to determine if high output of urine at night (also known as nocturnal polyuria) is a contributing factor by doing a voiding diary. Normal bladder capacity tends to decrease with age, but is usually in the 250-500 cc range (about 10-15 ounces). If your voiding diary shows that your night time voided volumes are in this range, the problem is not with the bladder.

 

The amount of urine which is produced at night is dependent on many factors, but most importantly:

  1. Fluid intake: the amount, type and timing are important: everything that you drink must come out at some point. Fluids consumed within a few hours of bed time will usually enter the bladder in a few hours. If the bladder becomes full, it should wake you up. Caffeine and alcohol are diuretics and can increase night time urine production and should be avoided.
  2. Fluid redistribution: this includes retention of fluid during the day with preferential urine formation during the night. Fluid accumulation earlier in the day - frequently in the legs - is common with congestive heart failure and venous insufficiency. Once asleep and in the horizontal position, the fluid is reabsorbed and increased urine output is the result. Diuretics and blood-pressure lowering pills may also cause increased urine output if they are taken close to bed time.
  3. Hormonal changes: vasopressin is a hormone released by the heart, mainly at night. One function is to temporarily reduce urine output during sleep. If secretion of vasopression is impaired, which is common with age, then increased urine output will ensue.
Insomnia

Often times, people will go to the washroom simply because they have awoken for other reasons. The do not specifically wake to urinate, but instead decide to go to the washroom because they happen to be awake.

 

People can have difficulty sleeping for a number of reasons including poor sleep hygeine and sleep apnea.

 

Diagnosis & Evaulation

Your urologist will take an appropriate history and physical and possibly perform additional tests to try to sort this out. The most important test is the voiding diary, which you can do before coming to the office. Paying attention to the types of fluids you take is also important. A basic evaluation should include:

  1. VOIDING DIARY - PLEASE DO THIS BEFORE COMING FOR YOUR APPOINTMENT
  2. Note of the types of fluids you consume, especially those containing caffeine such as coffee, tea, pop, alcohol
  3. Note medications that may affect fluid output - anti-hypertensives, diuretics
  4. Urine analysis and culture
  5. Other: may include a PSA, urine cytology, cystoscopy

 

Treatment

Treatment for nocturia depends on the underlying cause. If you require diretic therapy, you may need to take the medication earlier in the day to avoid it's effects occurring at night. A man with an enlarged prostate may benefit from either medication or surgery for it. Dietary adjustments are often incorporated in the treatment plan, such as avoiding excessive evening fluids and certain fluids as mentioned above, including coffee, tea, pop, and alcohol. Finally, there are several medications on the market that can help the bladder hold better at night. Your urologist will help you decide if any of these are appropriate for your situation.

 

Things to Minimize Urine Production at Night

  1. Avoid any caffeine after the morning: this includes coffee, tea, chocolate
  2. Avoid excessive fluid intake 4-6 hours before bed - this includes food and drinks
  3. Take diuretics and blood pressure pills earlier in the day. Check with your primary care physician first before changing dosing schedules.
  4. Pressure stockings are helpful to minimize fluid accumulation during the day if you have leg swelling. Stockings similar to those managed by Sigvaris can help and can often be found at the local pharmacy.
  5. Empty your bladder before bed - you may want to void more than once.

 

Sleep Hygeine. The following behaviors may help you sleep better at night.

  1. Fix a bedtime and an awakening time. Try to make it routine.
  2. Avoid napping during the day. A short nap or 'siesta' of about 30-45 min is probably not harmful.
  3. Avoid alcohol and caffeine for 4-6 hours before bed.
  4. Regular exercise, but not right before bed.
  5. Setting in the bedroom up: comfortable bedding, quiet, dark, temperature
  6. Reserve the bed for sleep and sex: avoid watching TV and taking work to bed.

 

Medications

Many medications can be used depending on the underlying cause - including medications to treat infection, prostate enlargement and overactive bladder.

 

In cases where high nightime urine output persists despite doing all the right things, DDAVP can be used. DDAVP is an analog of vasopressin and can 'turn off' the kidneys temporarily at night. Some patients may not be candidates for DDAVP if there is severe heart failure, high blood pressure, use of lithium and other conditions. Your urologist will discuss this with you.

 

Keys to taking DDAVP.

  1. Dose titration. The amount that each person needs is different. Slow, upward dose adjustment is sometimes needed. Most patients require 0.2-0.6 mg before bed.
  2. Restrict fluid intake for 1 hour before taking the medication and 8 hours after. If this is not done, fluid overload can result. One way to see if you are starting to retain fluid is to measure your weight before you start the medication and then periodically for a week or 2 after starting.
  3. It is critical that electrolytes (a blood test) are checked when starting the medication and with major dose adjustments - usually 5-7 days after starting, a few weeks later and then every 6 months or so.

 

On the Web

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