24 hour urine collection. Alternately, a pour-off sample from a 24 hour urine collection is acceptable but client must measure 24 hour urine volume and indicate the amount on the requisition.

24 Hour Urine Collections:—Collect as follows:
1. To begin the collection, empty the bladder and discard this urine. Record this time and date as the start of the collection.
2. 24 hour urine collections should be started Sunday through Thursday.
3. Collect all urine excreted during the next 24 hours in the urine collection container.
4. Exactly 24 hours after the collection was begun, empty the bladder for the last time. Add this urine to the 24 hour urine container. The collection is finished.
5. The container should be refrigerated during and after the 24 hour collection period until it can be brought to Saint Luke’s Regional Laboratories.

1. The request form must state the 24 hour urine volume.
2. Enter the urine volume into the MLAB prompt.

Frozen - 14 days
Refrigerated - 14 days
Room temperature - 14 days

Causes for rejection include the presence of blood in the urine and no preservative in the urine collection container.

83735 - Magnesium 24 HR Urine (EAP 30020577)
81050 - Urine Volume Measurement (EAP 30033360)