Influence of the storage temperature on urine analysis in timed samples

Ned Tijdschr Klin Chem Labgeneesk 2010, vol. 35, no. 3 Introduction The collection of a urine specimen over a predetermined time interval has the advantage of minimizing the short term biological variation of analytes. It is important that the patient follows close instructions for urine collection to obtain a proper 24-hours urine sample (1). One essential pre-requisite is that the collected urine should be kept in the refrigerator. In common practice, however, the storage of urine under cold temperatures seems unpractical and is often uncared for. When collected over the weekend, samples might be sent to the laboratory for analysis 24-72 hours after collection. To circumvent the problem of failure to refrigerate the sample when stored for longer periods, laboratories add preservatives before collection to reduce bacterial action or chemical decomposition. A disadvantage of the use of preservatives, however, is the possibility of interference with analytical methods. We investigated the effect of storage temperature and bacterial growth on the concentration of a panel of analytes.