Nocturia is defined as excessive urination at night, characterized by waking one or more times during the night to void 700 mL or more of urine. Normally, urine is more concentrated at night, allowing most individuals to sleep 6–8 hours without awakening. Nocturia may result from disruption of the diurnal pattern of urine concentration or from overstimulation of the nerves and muscles that control urination.

It is commonly associated with renal and lower urinary tract disorders, but can also occur in cardiovascular, endocrine, or metabolic disorders. Certain medications and excessive fluid intake, particularly caffeine or alcohol at bedtime, may exacerbate nocturia.

Pathophysiology

Nocturia occurs when normal urine production and bladder storage are disrupted:

• Renal causes: Impaired concentrating ability of the kidneys increases nocturnal urine output (e.g., chronic renal failure, hypercalcemic nephropathy, diabetes insipidus).

• Lower urinary tract obstruction: Conditions such as benign prostatic hyperplasia (BPH) or bladder tumors reduce functional bladder capacity, triggering frequent nocturnal voiding.

• Endocrine/metabolic: Diabetes mellitus causes osmotic diuresis; hormonal imbalances (e.g., atrial natriuretic peptide elevation) may increase nighttime urine production.

• Drug-induced: Diuretics, cardiac glycosides, and other medications can increase urine output, especially if taken in the evening.

• Behavioral/volumetric: Excessive evening fluid intake, caffeine, or alcohol can overwhelm normal nocturnal concentration mechanisms.

History and Physical Examination

History

• Onset, frequency, and pattern of nocturnal voiding

• Volume of urine per void

• Urine characteristics: color, odor, consistency

• Associated symptoms: dysuria, urgency, hesitancy, pain, flank or suprapubic discomfort

• Past medical/family history: renal disease, endocrine/metabolic disorders, diabetes

• Medication history: diuretics, cardiac glycosides, antihypertensives

• Fluid intake patterns

Physical Examination

• Kidneys: palpation and percussion

• Bladder: palpation for distension, bladder scan if available

• Urinary meatus: inspect for lesions or discharge

• Urine: color, odor, presence of sediment

Medical causes

Special considerations

• Monitoring: Intake and output, vital signs, daily weight, frequency and volume of nocturia, urine specific gravity

• Diuretic timing: Prefer daytime administration to reduce nocturia

• Patient education: Fluid management, voiding before bedtime, sleep compensation for nocturnal awakenings

• Diagnostics: Urinalysis, urine concentration/dilution studies, serum BUN, creatinine, electrolytes, cystoscopy

Patient counseling

• Reduce fluid intake before bedtime

• Avoid excessive caffeine and alcohol in the evening

• Discuss when to seek urgent medical care (hematuria, fever, flank pain)

• Monitor and document nocturia frequency and urine volume

Pediatric pointers

• Nocturia may be voluntary or involuntary (enuresis/bedwetting)

• Children with pyelonephritis are at higher risk for sepsis (fever, irritability, poor perfusion)

• Girls may present with vaginal discharge or vulvar soreness/pruritus

Geriatric pointers

• Postmenopausal women may experience nocturia due to decreased bladder elasticity

• Urine output remains normal; nocturnal awakenings may still occur

References

1. Berkowitz CD. Berkowitz’s Pediatrics: A Primary Care Approach. 4th ed. Elk Grove Village, IL: American Academy of Pediatrics; 2012.

2. Colyar MR. Well-child Assessment for Primary Care Providers. Philadelphia, PA: F.A. Davis; 2003.

3. Sommers MS, Brunner LS. Pocket Diseases. Philadelphia, PA: F.A. Davis; 2012.