What is the next step in managing an 80-year-old man with severe Coronary Artery Disease (CAD) and bothersome nocturia, with a large smooth prostate on Digital Rectal Exam (DRE), normal urinalysis, and elevated Post Void Residual (PVR) volume?

Management of Nocturia in an Elderly Man with CAD and BPH

The next step in managing this 80-year-old man with severe CAD and bothersome nocturia should be a voiding diary (option B).

Assessment of the Current Clinical Picture

The patient presents with:

• 80 years of age with severe coronary artery disease
• Bothersome nocturia
• Large, smooth prostate on DRE (suggesting BPH)
• Normal urinalysis
• Elevated post-void residual (PVR) of 140 mL

Diagnostic Approach for Nocturia in BPH

Initial Evaluation

The American Urological Association (AUA) guidelines recommend a systematic approach to evaluating men with lower urinary tract symptoms (LUTS) and nocturia:

1. Voiding diary: For patients with predominant significant nocturia, a frequency-volume chart (voiding diary) for 3 days is essential to determine the underlying cause 1. This helps distinguish between:

   • 24-hour polyuria (>3L/day)
   • Nocturnal polyuria (>33% of 24-hour urine output occurring at night)
   • Reduced bladder capacity
   • Mixed etiology

2. Post-void residual (PVR): Already completed at 140 mL, indicating some degree of urinary retention but not severe obstruction.

3. Urinalysis: Already completed and normal, ruling out infection and hematuria.

Why Voiding Diary is the Next Step

The voiding diary is particularly important in this case because:

• It helps identify the underlying mechanism of nocturia (nocturnal polyuria vs. reduced bladder capacity)
• It guides appropriate treatment selection 1
• It provides objective data on the severity and pattern of nocturia
• It can reveal contributing factors such as excessive evening fluid intake

Other Options Analysis

PSA Testing (Option C)

While PSA testing is recommended by the AUA for select patients 1, it is not the immediate next step for managing nocturia. PSA would be more relevant if there were concerns about prostate cancer or to guide 5α-reductase inhibitor therapy decisions.

Observation (Option A)

Simple observation is not appropriate given the patient's bothersome symptoms and elevated PVR, which indicate the need for active management 1.

Medication Options (D and E)

Oxybutynin (Option D)

Antimuscarinic medications like oxybutynin would be inappropriate as first-line therapy before determining the cause of nocturia because:

• The elevated PVR (140 mL) suggests some degree of bladder outlet obstruction
• Antimuscarinic agents can worsen urinary retention in men with BPH 1
• They should be used cautiously in elderly patients with cardiovascular disease

Desmopressin (Option E)

Initiating desmopressin without first confirming nocturnal polyuria would be premature and potentially dangerous because:

• Desmopressin is only indicated when nocturnal polyuria is confirmed 2
• It carries significant risks in elderly patients, including:
  • Hyponatremia
  • Fluid retention (particularly concerning in a patient with severe CAD) 2
  • Hypertension

Treatment Algorithm After Voiding Diary

Once the voiding diary is completed, treatment can be tailored based on findings:

1. If nocturnal polyuria is confirmed:

   • First address modifiable factors (evening fluid intake, timing of diuretics)
   • Consider desmopressin only after careful evaluation of risks, especially given the patient's age and CAD 2, 3

2. If reduced bladder capacity due to BPH is the primary cause:

   • Alpha-blockers would be appropriate first-line therapy
   • 5α-reductase inhibitors may be added if prostate is significantly enlarged

3. If mixed etiology:

   • Combination therapy may be required
   • Careful monitoring for adverse effects is essential

Conclusion

The voiding diary is the most appropriate next step as it provides critical information to guide treatment selection while avoiding potentially harmful empiric therapy. This approach is consistent with AUA guidelines for the management of LUTS in older men with BPH 1.