Storage Of Urine Specimens Research Articles

Storage of urine specimens in point of care (POC) urine drug testing cups reduces concentrations of many drugs

BackgroundMany clinical toxicology laboratories receive urine specimens in urine cups that contain point of care (POC) drug testing strips. We conducted this study to evaluate the effect on the stability of commonly measured drugs in the clinical toxicology laboratory when urine is exposed to POC urine drug testing cups. MethodsDrug free urine was spiked with 85 drugs that were measured by a validated liquid chromatography mass spectrometry (LCMS) method after exposure to POC urine drug testing cups at ambient and 2–6 °C temperatures. Alterations ≥20% were defined as significant changes in the drugs concentration. ResultsConcentrations of amitriptyline, cyclobenzaprine, fentanyl, fluoxetine, flunitrazepam, nortriptyline, paroxetine, and sertraline were significantly reduced when urine specimens were stored inside POC urine drug testing cups for 24 h at ambient temperature. Storage of urine in urine chemistry dipsticks reduced the concentration of several drugs. When spiked urine was exposed to an increasing number of POC urine drug testing strips, the concentrations of some drugs were reduced in a dose-dependent manner. The drugs that were absorbed by POC urine drug testing strips were partially back extracted from the strips. ConclusionExposure of urine specimens to POC urine drug testing strips reduces the concentration of several drugs measured by LCMS method.

Effects of storage conditions on results for quantitative and qualitative evaluation of proteins in canine urine.

OBJECTIVE To investigate effects of storage conditions on the canine urine protein-to-creatinine ratio (UPC) and on SDS-agarose gel electrophoresis (AGE) of urinary proteins. SAMPLE Urine specimens from 20 proteinuric (UPC > 0.5) and 20 nonproteinuric (UPC ≤ 0.2) dogs. PROCEDURES UPC and SDS-AGE were performed on urine specimens stored at room temperature (20°C) and 4°C for up to 5 days and at -20° and -80°C for up to 360 days; some specimens were subjected to 3 freeze-thaw cycles. Results were compared with those obtained for fresh urine specimens. RESULTS UPC was not affected by storage at room temperature or by freezing. A decrease in UPC was observed for specimens from nonproteinuric dogs after 5 days at 4°C (10%) and from both groups after 90 days at -20° and -80°C (≤ 20% and ≤ 15%, respectively). The SDS-AGE profiles revealed no visual changes regardless of duration of storage for specimens stored at room temperature, 4°C, and -80°C, except for 1 profile after 360 days at -80°C. Repeated freeze-thaw cycles did not affect SDS-AGE profiles. Appearance or strengthening of high-molecular-weight bands that could alter interpretation was evident in SDS-AGE profiles after storage at -20°C for ≥ 15 days (31/40 dogs). CONCLUSIONS AND CLINICAL RELEVANCE Storage of urine at -20° or -80°C for up to 1 year influenced the UPC without affecting clinical interpretation. Storage of urine specimens at -20°C impaired visual analysis of SDS-AGE. When SDS-AGE cannot be performed on fresh or recently refrigerated urine specimens, storage at -80°C is recommended.

Optimization of storage conditions for cocaine and benzoylecgonine in urine: a review.

The maximum stability conditions for cocaine and its metabolite benzoylecgonine (BE) in urine were analyzed. Suggestions were presented after careful review of many studies and personal communications concerning cocaine and BE stability in urine. The optimal storage conditions for urine specimens with cocaine and BE were determined to be at -15 degrees C and a pH of 5.0. Ascorbic acid was found to be a favorable agent to attain this acidic pH. Unsilanized glass was determined to be a favorable container material. Storage in darkness was also supported. Storage of urine specimens under these conditions was believed to prevent degradation of cocaine and benzoylecgonine for at least 110 days.

Basic urinalysis and urine culture: Finnish recommendations from the working group on clean midstream specimens

A recommendation for basic urinalysis and urine culture is published as an attempt to improve the clinical value of urinary tests and to create a system that utilizes laboratory work as sensibly as possible. More clinical background information is needed when basic urinalysis and urine culture is performed in stages. Collection and storage of urine specimens are standardized in addition to used equipment and bacterial culture. Cytological supravital stain improves qualitative and quantitative findings of urine sediment cytology. A close cooperation between central hospital district is necessary and stressed for further bacterial cultures in more complicated microbiological findings.

Factors affecting measurement of urinary oxalate.

Using a gas-chromatographic method, we examined the effects of phosphate concentration, added calcium chloride, and pH on precipitation of oxalate from urine. All three factors are important, but the pH of precipitation is particularly so, especially in the presence of even normal concentrations of ascorbic acid. At pH 8, increases in measured oxalate ranged from 20% at an ascorbic acid concentration of 1 mmol/L to more than 300% at 15 mmol/L. Ascorbic acid is rapidly converted to oxalate at alkaline pH. We also investigated the stability of both untreated and acidified urine containing ascorbic acid during storage for up to one month at -70, -20, and 4 degrees C, and room temperature. After one month, untreated collections were stable at -70 degrees C and acidified collections at -20 and -70 degrees C. We recommend conditions for assay and storage of urine specimens that are to be assayed for oxalate under which positive interference by ascorbic acid is minimized.

The Preservation of Urine Specimens for δ-Aminolevulinic Acid Determination

Abstract The effect of light exposure and temperature on urinary δ-aminolevulinic acid recovery was studied. Addition of tartaric acid and storage of urine specimens in the dark results in excellent recovery of δ-aminolevulinic acid, even after several days at room temperature. Proper handling and storage of urine collected during surveys of lead poisoning are emphasized.