Your 24-Hour Urine Collection is Proceeding Correctly—Continue as Planned
You should continue your 24-hour urine collection exactly as instructed, collecting all urine for the remaining 11 hours. Your current output of 900ml in 9 hours and yellow urine color are both normal findings that do not require any changes to your collection protocol 1.
Why Your Collection is On Track
Urine volume varies throughout the day and is not expected to be uniform. The 900ml you've produced in 9 hours represents a reasonable output rate, and you will likely produce more urine during the remaining 11 hours, especially if you maintain adequate fluid intake 1, 2.
- Your total 24-hour urine volume will be measured at the end of the collection period, and the goal is typically at least 2.0-2.5 liters total daily output for stone prevention purposes 1.
- Urine production is influenced by fluid intake timing, insensible losses, and water content in foods—it is not constant throughout the day 1.
Urine Color is Not a Reliable Guide
Despite what some clinicians believe, there are no data to support using urine color as a guide for hydration status or collection adequacy 1.
- Yellow urine does not indicate a problem with your collection 1.
- The desire to have constantly dilute (very light colored) urine needs to be balanced against practical considerations 1.
- Laboratory measurement of urine osmolality and specific gravity are the accurate methods to assess urine concentration, not visual color assessment 3.
Critical Collection Instructions for the Remaining 11 Hours
Collect every single void completely during the remaining time period 4, 2.
- Do not discard any urine during the collection period 4.
- The final void at the end of your 24-hour period should be included in the collection 4.
- Keep the collection container refrigerated at 4-10°C if possible, or in a cool location 1, 4.
Maintain your normal diet and fluid intake 1, 2.
- The collection should be performed on your random, usual diet unless you were given specific dietary instructions 1, 2.
- Do not artificially increase or decrease your fluid intake to try to produce more or less urine, as this will invalidate the metabolic assessment 5.
- Approximately one-third of patients inappropriately change their drinking habits during collection, which compromises test accuracy 5.
Common Pitfalls to Avoid
Do not assume the collection is invalid based on intermediate volume or color 1, 5.
- The laboratory will measure total 24-hour volume and creatinine excretion to verify collection completeness 1, 2.
- Incomplete collections are identified by low total volume and low creatinine excretion, not by color or intermediate volumes 1, 2.
Ensure you understand the exact start and end times 4, 5.
- Most protocols require discarding the first morning void at the start time, then collecting all subsequent urine including the final void at exactly 24 hours later 4.
- Poor adherence to collection instructions is common, with studies showing most patients are inadequately informed about proper procedure 5.