What is the appropriate workup and management for a patient presenting with nocturia?

Workup for Nocturia

Begin with a mandatory 72-hour bladder diary to distinguish between nocturnal polyuria (>33% of 24-hour urine output at night) and reduced bladder capacity, as this single tool determines your entire treatment pathway. 1, 2

Essential History Components

SCREeN Framework Assessment

Systematically screen for underlying medical causes using the SCREeN framework (Sleep disorders, Cardiovascular disease, Renal disease, Endocrine disorders, Neurological disease) rather than assuming a primary urological etiology 1, 2:

• Sleep disorders: Ask "Do you snore and wake up choking?" for obstructive sleep apnea; "Do you have difficulty falling or staying asleep?" for insomnia; "Does your bed partner complain that you have twitchy legs?" for restless legs syndrome 1
• Cardiovascular: Ask "Do you experience ankle swelling?" and "Do you get short of breath on walking?" to identify heart failure 1
• Renal: Same questions as cardiovascular, plus review for chronic kidney disease history 1
• Endocrine: Ask "Have you been feeling excessively thirsty?" for diabetes; inquire about thyroid symptoms 1
• Neurological: Ask "Do you have problems controlling your legs? Slowness of movement? Tremor?" for Parkinson's disease or autonomic dysfunction 1

Medication Review

Identify drugs contributing to nocturia 1, 2:

• Diuretics (note timing of administration)
• Calcium channel blockers (cause peripheral edema)
• Lithium, NSAIDs (affect renal function)
• Xerostomia-causing drugs: anxiolytics, tricyclic antidepressants, antimuscarinics, antihistamines, decongestants, antiparkinsonians, antipsychotics 1
• Alcohol and caffeine (diuretic effects) 1

Physical Examination

Focus on specific findings rather than a general examination 1, 2:

• Oral cavity: Check for reduced salivation and xerostomia 1
• Lower extremities: Assess for peripheral edema suggesting cardiac or renal disease 1
• Neurological: Evaluate for lower limb weakness, abnormal gait, speech abnormalities, or tremor 1
• Blood pressure: Measure lying and standing BP within 1 minute and at 3 minutes to detect orthostatic hypotension (>20 mmHg systolic or >10 mmHg diastolic drop) 1, 2

Baseline Investigations

Order the following tests for every patient with nocturia 1, 2, 3:

• 72-hour bladder diary (mandatory—calculate if >33% of urine output occurs at night) 1, 2, 3
• Blood tests: electrolytes/renal function, thyroid function tests, serum calcium, HbA1c 1, 2, 3
• Urinalysis with dipstick: check for albumin:creatinine ratio, blood, protein 1, 2, 3
• Blood pressure assessment including orthostatic measurements 1, 2, 3
• Pregnancy test where applicable 1

Treatment Algorithm Based on Bladder Diary Results

If Nocturnal Polyuria is Present (>33% of 24-hour output at night):

1. First-line: Restrict evening fluid intake to ≤200 mL after dinner 4, 2
2. Adjust diuretic timing: Administer diuretics mid-to-late afternoon (4-6 hours before bedtime depending on half-life) 1, 2
3. Pharmacotherapy: Low-dose desmopressin is the only medication specifically approved for nocturia due to nocturnal polyuria, but use with extreme caution in patients >65 years due to hyponatremia risk 4, 5, 6

If Reduced Bladder Capacity is Present:

1. For men with prostatic symptoms: Alpha-blockers (tamsulosina) can reduce nocturnal frequency 4
2. For overactive bladder symptoms: Consider mirabegron over antimuscarinics in patients >80 years due to lower cognitive impairment risk 3

If SCREeN Condition is Identified:

Treat the underlying medical condition first rather than empirically treating with urological medications 1, 2:

• Sleep apnea: Refer to sleep medicine for CPAP evaluation 1
• Heart failure: Optimize cardiac medications and consider compression stockings for daytime edema mobilization 1
• Diabetes: Optimize glycemic control 1
• Parkinson's disease: Adjust timing of antiparkinsonian medications to minimize nocturnal effects 4

Special Considerations for Older and Frail Patients

Prioritize fall prevention over complete symptom resolution in patients >80 years or those with frailty 1, 3:

• Provide bedside commode or handheld urinal container 1, 2
• Ensure adequate nighttime lighting and remove obstacles between bed and bathroom 1, 2
• Recognize that cognitive impairment limits ability to follow complex medication regimens 2
• Consider that frailty and life expectancy should guide treatment intensity 1, 3

Critical Safety Warnings

• Fall and fracture risk: Nocturia significantly increases fall risk, especially when combined with orthostatic hypotension from alpha-blockers in Parkinson's patients 4, 7
• Driving safety: Patients must avoid driving when excessively fatigued from sleep disruption 1, 2
• Hyponatremia monitoring: If desmopressin is used in patients >65 years, check serum sodium at baseline, 3 days, and 1 week after initiation 3

When to Refer to Urology

Refer if symptoms persist despite optimal treatment of underlying SCREeN conditions and appropriate conservative management, or if concerning features are present 1, 3:

• Hematuria on urinalysis 3
• Elevated post-void residual volume 3
• Suspicious neurological symptoms (numbness, weakness, speech disturbance, memory loss) requiring direct neurology referral 1
• Consideration for advanced therapies (onabotulinumtoxinA injection, sacral neuromodulation, prostate surgery) 7