How to carry out a 48-hour urine collection

This leaflet is intended for all patients who have been asked by their clinician (doctor or nurse) to collect two 24-hour urine samples at home.

Important decisions regarding your treatment may depend entirely upon proper test results. It is most important that you make sure that your collections are complete. An incomplete collection can give misleading results.

Please read the instructions carefully; make sure you are prepared, and follow each of the steps to ensure proper collection.

Materials supplied:

• Two five litre containers
• Two green plastic carrier bags

Before you start your collection

You may drink as much fluid as you normally would during each of the 24 hour collection periods. Plan your collection for a day off or a weekend, but if you plan to go out, you need to take your collection bottle with you.

• It is essential that the collection procedure described below is followed very carefully.
• Test results are based on the total amount of tested urine excreted by your body over two consecutive 24 hour periods.
• You should collect every drop of your urine during the specified 48-hour period.
• It does not matter what the volume of the urine is, as long as it represents every drop that you pass.
• If you have a bowel movement, you must collect the urine separately.
• If unable to do so you should abandon the collection and start again on another day, using a fresh container.

Collection procedure

Please do not pass urine directly into the container. If necessary collect the urine firstly into a clean, dry, non-metallic object (such as a bowl or jug) and then pour it into the container. If you have a funnel this would be very useful.

Since the information your clinician gets from these samples is only as accurate as your collection procedure, it is most important that you collect the urine as follows:

1. Begin at the usual time that you wake.
2. At that time, pass your urine, flush it down the toilet and note the exact time. You will now have an empty bladder and an empty bottle. The collection of urine for 48 hours will start from this time. Please note both the date and time on the collection bottle label, where it says ‘start date and time’.
3. Collect every drop you pass during the day and night, for 24 hours, and finish the collection by passing urine at exactly the same time the next morning. You should add this final specimen to the first bottle.
4. This is the end of the first collection. Please note both the date and time on the collection bottle label, where it says ‘finish date and time’.
5. You are then ready to begin the second 24 hour collection in the second bottle for the second 24 hour period.
6. Check that the bottle labels contain your full name, date of birth, clinic or GP surgery that requested the collection and the date of collection.
7. Please check that the cap is firmly screwed onto each container. Then put the bottles in the bags provided. Unfortunately if the urine leaks in transit, the collection will be invalidated and the analysis will not be carried out.
8. Keep the sample containers cool, closed and protected from light between each time you pass urine.

After completing your collection

Should you have to, you can store the bottle at a cool room temperature for a day or two. Ideally you should hand the sample into the clinical biochemistry laboratory at Addenbrooke’s or your doctor’s surgery, in the bag provided, as soon as possible after completing the collection.

If there is a delay in handing the sample after completion, the bottle should be kept cool or refrigerated (not frozen).

Finally, many people get their urine collection wrong despite the best of intentions. It is better to admit this and discard an imperfectly collected sample rather than hand in a partial sample which would yield an inaccurate result. returning an incomplete sample would affect important decisions with regard to your treatment.

Please call the endocrine investigations unit on 01223 217848, if you need any further explanation.