Phlebotomists may be required to manage urine collections, both 24-hour and random. Adherence to the laboratory's specific policies and protocols is always required. Coordinators of urine sample collection will need to educate patients as to the safe and effective handling of urine collection with established instructions.
The importance of preservatives is stressed when collecting a 24-hour urine sample to minimize the degradation associated with variable handling and storage conditions.The stability of some of the components excreted in the urine are affected by the change in pH that occurs in the collected sample. Urine pH often becomes more alkaline upon collection due to the presence and ongoing metabolism of bacteria and viable cells that are excreted. Certain analytes are better suited for a pH that is closer to what is found within the urinary system, while others require a more acidic pH to minimize the deterioration of the desired measurands.
Commonly used urine preservatives include boric acid, hydrochloric acid, acetic acid, and oxalic acid. Certain buffers and bicarbonate salts may also be used for specific measurands. Laboratories need to evaluate the effectiveness and potential interference of preservatives.
Random urine collections can usually be held for 2 hours at room temperature with protection from light. Specimens may be held longer if refrigerated or preserved according for laboratory protocol.
