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

Nocturia Workup in Men

Begin with a 72-hour bladder diary to determine the underlying mechanism—this single diagnostic tool will guide all subsequent treatment decisions and is more important than any other initial test. 1

Initial Clinical Assessment

Essential History Components

• Medication review is critical: specifically assess diuretics, calcium channel blockers, lithium, NSAIDs, and drugs causing dry mouth (anxiolytics, tricyclic antidepressants, antimuscarinics, antihistamines, decongestants, antiparkinsonians) 1
• Timing of diuretic administration must be documented, as this directly impacts nocturnal urine production 1
• Fluid intake patterns, particularly alcohol and caffeine consumption, which have diuretic effects 1

SCREeN Screening Questions (Sleep, Cardiac, Renal, Endocrine, Neurological)

Ask every patient these specific questions to identify non-urological causes 1:

Sleep disorders:

• "Do you have problems sleeping aside from needing to get up to urinate?" 1
• "Have you been told that you gasp or stop breathing at night?" 1
• "Do you wake up without feeling refreshed? Do you fall asleep in the day?" 1

Cardiac/Renal:

• "Do you experience ankle swelling?" 1
• "Do you get short of breath on walking for a certain distance?" 1

Neurological:

• "Do you get lightheaded on standing?" 1
• "Do you have any problems controlling your legs? Do you experience slowness of movement? Have you noticed a tremor in your hands?" 1

Endocrine:

• "Have you been feeling excessively thirsty?" 1

Physical Examination

• Assess for peripheral edema (suggests cardiac or renal disease) 1
• Evaluate for reduced salivation or scleroderma (indicates xerostomia contributing to fluid intake) 1
• Check for lower limb weakness, abnormal gait, speech abnormalities, or tremor (neurological dysfunction) 1
• Blood pressure measurement is mandatory, including lying and standing measurements within 1 minute and at 3 minutes (a fall of 20 mmHg systolic or 10 mmHg diastolic indicates orthostatic hypotension and autonomic failure) 1

Baseline Investigations

Mandatory Initial Tests

• 72-hour bladder diary (frequency-volume chart): This will reveal nocturnal polyuria (>33% of 24-hour output at night), reduced bladder capacity (small voided volumes), or global polyuria (>2.5-3 liters per 24 hours) 1, 2, 3
• Blood tests: electrolytes/renal function, thyroid function, calcium, HbA1c 1
• Urinalysis with dipstick: albumin:creatinine ratio, blood, protein 1
• Blood pressure assessment 1

Additional Testing Based on Screening Results

If sleep disorder suspected (based on positive screening questions) 1:

• Use STOP-BANG questionnaire for obstructive sleep apnea 1
• Refer for overnight oximetry 1
• Check ferritin level if restless legs syndrome suspected (supplementation if <75 ng/ml) 1

If cardiovascular disease suspected 1:

• Electrocardiogram 1
• Brain natriuretic peptide; echocardiogram if positive 1

If renal disease present or suspected 1:

• Renal ultrasound 1
• Urine albumin:creatinine ratio 1

If endocrine disorder suspected 1:

• If hypercalcemia detected: parathyroid hormone and endocrinology referral 1
• Morning urine osmolarity after overnight fluid avoidance (>600 mosm/L rules out diabetes insipidus) for patients urinating >2.5 L per 24 hours 1

If neurological disease suspected 1:

• Lying/standing blood pressure measurements 1
• Assessment of activities of daily living 1
• Direct neurology referral if new-onset severe lower urinary tract symptoms, enuresis without chronic retention, or "suspicious" symptoms (numbness, weakness, speech disturbance, gait disturbance, memory loss, autonomic symptoms) 1

Treatment Algorithm Based on Bladder Diary Results

For Nocturnal Polyuria (>33% of 24-hour output at night)

• First-line: Fluid restriction starting 1 hour before bedtime, targeting approximately 1 liter total 24-hour output 4
• Pharmacological: Desmopressin 0.1 mg orally at bedtime is the only medication specifically indicated for nocturnal polyuria 4, 3, 5
• Address modifiable factors: weight reduction if elevated BMI, avoid excessive alcohol and highly seasoned foods 4

For Reduced Bladder Capacity

• Alpha-blocker therapy (tamsulosin 0.4 mg daily) should be started immediately 2, 6
• Assess effectiveness after 2-4 weeks 2, 6
• Consider 5α-reductase inhibitors if prostate enlargement present (assess after 3 months) 7

For Global Polyuria (>3 liters per 24 hours)

• Evaluate for uncontrolled diabetes, excessive fluid intake, or compulsive water drinking 2
• Address behavioral factors 2

Common Pitfalls to Avoid

• Do not assume nocturia is solely a bladder problem—up to 80% of men with benign prostatic hyperplasia and nocturia have nocturnal polyuria as a contributing factor 7
• Do not use fluoroquinolones if considering urinary tract infection as a contributor in elderly patients with comorbidities and polypharmacy 4
• Fall prevention is critical: implement bedside commodes, adequate lighting, and fracture risk assessment in elderly patients 2
• Monitor for hyponatremia when using desmopressin, though risk is reduced with low-dose formulations 7

Follow-Up Strategy

• Reassess at 2-4 weeks after initiating desmopressin to evaluate efficacy and adverse events 4
• Repeat frequency-volume chart to document objective improvement 4
• Annual follow-up once nocturia is controlled, with repeat symptom scoring, monitoring for disease progression, and reassessment for new medical conditions 2, 4

Referral Criteria

Immediate urology referral indicated for 2:

• Hematuria 2
• Recurrent urinary tract infections 2
• Palpable bladder 2
• Severe obstruction (peak flow <10 mL/second) 2
• Neurological disease affecting bladder function 1, 2