Nocturia

Anna M. Wright and Vincent H. Ober

Approach

 Nocturia, defined as awakening from sleep to urinate, is a frequent symptom in patients of all ages and it is associated with many disease processes. Nocturia is usually caused by increased urine output, sleep-related difficulties, or urinary tract dysfunction (1). A careful history with a focused physical examination and laboratory tests are the most important diagnostic tools.

History

Possible causes of nocturia include:

A. Increased urine output. The history should include questions concerning the following causes of increased urine output:

1. Excess intake of fluids

2. Drugs (i.e., caffeine, alcohol, diuretics, nonsteroidal antiinflammatory drugs, calcium channel blockers, lithium)

3. Diabetes mellitus (Chapter 14.1)

4. Diabetes insipidus (central or nephrogenic)

5. Hypercalcemia (Chapter 17.4)

6. Peripheral edema (from any cause) (Chapter 2.3)

7. Congestive heart failure (Chapter 7.5)

8. Renal disease

9. Aging (1)

B. Sleep-related nocturia. Disrupted sleep will cause a patient to arise and empty a partially filled bladder. Causes of disrupted sleep include:

1. Use of a short-acting sedative hypnotic

2. Pain (acute or chronic)

3. Dyspnea (from pulmonary or cardiac disease) (Chapter 8.7)

4. Anxiety or depression

5. Drugs that interfere with the sleep cycle (2)

6. Parkinson’s disease

C. Dementia

D. Sleep apnea (3)

E. Urinary tract dysfunction. Causes of lower urinary dysfunction include:

1. Lower urinary tract infection

2. Small bladder capacity

3. Detrusor hyperactivity

4. Prostatic hypertrophy

5. Urinary retention for any reason

 6. Decreased bladder compliance (interstitial cystitis, radiation, tuberculosis) (2)

 7. Sensory stimulation in a paraplegic

8. Neurogenic bladder (spastic or atonic) from multiple sclerosis, cerebrovascular accidents, herniated disks, or spinal cord injury

9. Obstetric, gynecologic, or urologic disease or injury

10. Chronic obstructive pulmonary disease (COPD) (4)

11. Fecal impaction

Physical examination

The extent of the physical examination will be guided by the history. Essential for all patients is a genitourinary examination to identify lower urinary tract abnormalities such as bladder distention, cystocele, or rectocele. Examination of the heart, lungs, and extremities will identify pulmonary, cardiac disease, and peripheral edema. A rectal examination (with sphincter contraction during the examination) will identify sphincter laxity, fecal impaction, tumors, and prostate abnormalities. Absence of the anal wink (S4-5) or bulbocavernosus reflex (S2-3) can indicate spinal cord pathology. (In older patients, the absence of these reflexes is not always pathologic.) An expanded neurologic examination will be necessary in patients with other neurologic symptoms.

Testing

 A routine urinalysis by dipstick testing will identify infection and some types of renal disease. A low specific gravity can indicate increased fluid intake or renal disease with the inability to concentrate urine. Microscopic evaluation and urine culture can be helpful in selected cases. Serum blood urea nitrogen and creatinine can be elevated in renal disease. Urine electrolytes can help to diagnose diabetes insipidus. Measurement of postvoid residual urine will evaluate for urinary retention. A voiding diary with measurement of urine volume can be helpful. If the nighttime voided urine volume is high, the cause is excessive urine production. If the volume is less than bladder capacity (highest daytime voided volume), the nocturia is caused by a sleep-related problem or lower urinary tract pathology. Cystoscopy, renal ultrasound, intravenous pyelogram, and urodynamic studies are not usually needed in the evaluation of nocturia.

Diagnostic assessment

Patients with excessive fluid intake or use of alcohol or caffeine near bedtime or patients on medications (e.g., diuretics, theophylline, or calcium channel blockers) may complain of nocturia. Aging is associated with a loss of the nocturnal increase in vasopressin and increased nocturnal urine production (2). Nocturia, frequency, urgency, and dysuria coupled with a positive urinalysis indicate a urinary tract infection. Findings of rales on lung examination, an S₃ gallop, and lower extremity edema suggests congestive heart failure. COPD can cause respiratory acidosis and increased excretion of hydrogen ion with the production of an acid urine and bladder irritation (4). In a male patient, a diminished urinary stream and an enlarged prostate suggest prostatic hypertrophy and obstructive uropathy. Patients with insomnia from any number of causes (depression, pain, dyspnea, and so on) may experience nocturia. Be alert for the patient with nocturia secondary to neurologic conditions, which can cause inadequate secretion of vasopressin (diabetes insipidus).

References

1. Resnick NM. Urinary incontinence. In: Cassel CK, Cohen HJ, Larson EB, et al., eds. Geriatric medicine, 3rd ed. New York: Springer-Verlag, 1997:562–566.

2. Donahue JL, Lowenthal DT. Nocturnal polyuria in the elderly person. Am J Med Sci 1977;314(4):232–237.

3. Pressman MR, Figueroa WG, Kendrick-Mohamed J, Greenspon LW, Peterson DD. Nocturia. A rarely recognized symptom of sleep apnea and other occult sleep disorders. Arch Intern Med 1996;156(5):545–550.

4. McAninch JW. Symptoms of disorders of the genitourinary tract. In: Tanagho EA, McAninch JW, eds. Smith’s general urology, 14th ed. Norwalk, CT: Appleton & Lange, 1995:36–38.

Book Source Details

• Book Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter
• Author(s): Robert B. Taylor (editor)
• Year of Publication: 2000
• Copyright Details: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter, Copyright © 2000 Lippincott Williams & Wilkins.

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More About This Book: Title: The 10-Minute Diagnosis Manual: Symptoms and Signs in the Time-Limited Encounter Authors: Robert B. Taylor (editor) Publisher: Lippincott Williams & Wilkins Copyright: 2000 ISBN: 0-78172-094-X

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