Example of a 72-Hour Frequency Volume Chart for Nocturia Assessment
A 72-hour frequency volume chart is an essential tool for evaluating nocturia, recording the time and volume of each urination over three consecutive 24-hour periods to identify patterns of nocturnal polyuria and reduced bladder capacity. 1
Components of a Standard 72-Hour Frequency Volume Chart
- Time and volume recording: Document the exact time and measured volume (in mL) of each void throughout the day and night for 3 consecutive days 1
- Fluid intake tracking: Record the time and amount of fluid intake throughout the day 2
- Sleep/wake times: Note when the patient goes to bed and wakes up to differentiate between daytime and nighttime voids 1
- Urgency sensation scale: Include a rating system for the level of urgency experienced before each void 1
- Incontinence episodes: Document any episodes of urinary leakage 1
Sample Format for a 72-Hour Frequency Volume Chart
Day 1 (Date: __________)
| Time | Voided Volume (mL) | Fluid Intake (mL) | Urgency Level (0-3)* | Comments |
|---|---|---|---|---|
| 7:00 | 250 | 0 | 1 | Morning void |
| 7:30 | 0 | 200 (coffee) | - | - |
| 10:15 | 180 | 0 | 1 | - |
| 12:00 | 0 | 300 (water) | - | - |
| 14:30 | 220 | 0 | 2 | - |
| 18:00 | 200 | 0 | 1 | - |
| 19:00 | 0 | 250 (tea) | - | - |
| 22:00 | 230 | 0 | 2 | Before bed |
| 02:15 | 180 | 0 | 3 | Nighttime void |
| 05:30 | 210 | 0 | 3 | Nighttime void |
*Urgency Level: 0=no urgency, 1=mild urgency, 2=moderate urgency, 3=severe urgency
Clinical Interpretation Guidelines
Key Metrics to Calculate
- 24-hour urine output: Total volume of urine produced in 24 hours (>3000 mL indicates global polyuria) 3, 4
- Nocturnal urine volume: Total volume of urine produced during sleep 1
- Nocturnal polyuria index (NPi): Proportion of 24-hour urine output produced during sleep hours (>33% in adults indicates nocturnal polyuria) 5
- Nocturnal bladder capacity: Maximum and average voided volumes during nighttime 6
- Nocturia index (Ni): Nocturnal urine volume divided by the largest single voided volume 5
- Nocturnal urine production per hour (NUPh): More specific for nocturnal polyuria than other indices 5
Diagnostic Categories Based on Chart Analysis
- Global polyuria: 24-hour urine output >3000 mL 4
- Nocturnal polyuria: Excessive urine production during sleep hours 1
- Reduced bladder capacity: Mean 24-hour bladder capacity <200 mL 6
- Mixed etiology: Combination of nocturnal polyuria and reduced bladder capacity 6
Practical Tips for Implementation
- Patient education: Provide clear written instructions on how to complete the chart accurately 1
- Measurement tools: Supply a graduated container for precise volume measurement 2
- Timing: Include both weekdays and weekend days to capture lifestyle variations 2
- Validation: Ensure the chart is completed for the full 72 hours for reliable assessment 1
- Follow-up: Use the completed chart to guide treatment decisions and monitor progress 1
Common Pitfalls to Avoid
- Incomplete recording: Missing entries compromise the reliability of the assessment 2
- Inaccurate volume measurement: Using household containers without proper measurement markings 1
- Failure to distinguish sleep time from bed time: Important for accurate nocturnal polyuria assessment 1
- Not recording fluid intake: Essential for identifying polydipsia as a potential cause 1
- Short duration of recording: A single 24-hour period may not capture typical patterns 2