A sample of urine collected over a specified period of time.
For a short time (2 hours) you may be asked to do this at the laboratory.
For longer collections (e.g. 12 or 24 hours) you will do this at home.
At the beginning of the time period, empty your bladder and discard that urine. Note the time. Collect all urine passed (voided) during the specified period of time. At the end of the time period, empty your bladder and ADD this urine to the container. Note the time.
Bring all of the urine collected to the laboratory or doctor's surgery.