Impacting Factors

Point of Care Test kits (POCT)

It is important to realize that the chemical reaction that occurs in POCTs can be impacted by a wide-range of environmental, chemical and physical conditions. Being able to identify these situations can help prevent inaccurate readings and potentially explain unexpected results.

ENVIRONMENTAL DISRUPTION

POCT STORAGE TEMPERATURES​

Store all POCTs at room or moderate temperatures.

Try to avoid storing POCTs at extreme temperatures, even for a short period of time. Rapidly changing temperatures can also overwhelm the descant material if the POCT packaging has any small puncture. .

 

EXTREME COLD and EXTREME HOT storage temperatures will make the POCT results less reliable. and may even cause POCT strip failures. If your supply of POCTs has been stored in questionable temperatures, test the products on controls or known outcomes (both positive and negative) before using consequentially.

POCT USE TEMPERATURES

Storing POCTs at extreme temperatures is not the only way a POCT can be impacted by temperature. Using a POCT that has been stored in cold temperatures below 45 degrees without first bringing the POCT back to room temperature can significantly impact

 

  • the speed at which the POCT chemistry occurs

  • cool the specimen below proper temperature range causing a false temperature strip reading

  • fog up the POCT housing, making light lines harder to recognize.

PHYSICAL DISRUPTION

SHAKING OR INVERTING A POCT WITH SPECIMEN

Do not to shake or invert a POCT that contains a specimen. Shaking or inverting a POCT will not cause the POCT to run faster, but will more likely cause an invalid or false result.

 

Certain donors have learned that shaking a POCT can invalidate the test result causing the collector to either retest or document the result as negative. Shaken POCTs can be easy to identify. There are several characteristics of a shaken POCT sample. Both shaken/inverted urine and oral will have specimen in areas of the POCT housing where specimen should not be. Droplets of specimen in areas of the POCT housing protected by ambient pressure (on most POCTs in the result window between the POCT strips and the viewable housing) should always remain dry.  Another indicator is the amount of bubbles. Some donor urine will contain bubbles, especially donors with kidney problems. A shaken POCT with specimen will stand out and look abnormally "bubbly". The last indicator, and the most important, is faint or failed strips. If all three of these attributes exist, you may have a tampered POCT and should consider transferring the specimen to another POCT or better yet, recollect a new specimen.

 

SAMPLE SUBSTITUTION

Watch our for donors that attempt to present borrowed urine. Sample substitution is extremely hard to detect by even some experienced collectors. There are several attributes to look for when combating substitution.

 

  • Cloudy samples

  • Samples with anything floating

  • Too cold or too hot

  • Specimen on the outside of POCT housing

  • Donors that take too long to provide a specimen

Not all of the above are signs of substitution, but are key indicators to consider before requesting a second sample from a donor. 

WAITING TOO LONG AFTER OPENING A POCT

Although some POCTs will work even after remaining opened from the protective packaging, it is best to discard any POCT that has been opened for more than four hours. Aside from chain of custody violations and failing to follow best practices, using a pre-opened POCT could cause false results.

SYNTHETIC URINE

On of the greatest challenge a dishonest donor will face when attempting to use a synthetic sample is ensuring the temperature is in range. In the development of SmartReader, we discovered that donor may overheat the sample using hand warmers. Each time a urine sample is collected, pay close attention to the temperature of the specimen and how developed the lines appear. Most tests take 3-5 minutes for the lines to completely develop. If a donor hands you a sample that has fully developed lines and a temperate of 98˚ or higher, there is a very high probability that the sample is not authentic and a recollection should be considered.

CHEMICAL DISRUPTION

INEFFECTIVE ADULTERANTS

Not all adulterants sold online or touted on the Internet are effective. The fact is that there are only a few adulterants that can be added to a Urine specimen that are effective against POCTs. When uneducated donors use the wrong adulterant products or methods, it is possible for adulterant to disrupt one or more test lines, causing multiple positive results and/or disruption to the control lines. If a specimen that has produced a "Failed result" is transferred to another POCT and the same disrupted result is achieved, consider sending the specimen to the lab for confirmation testing or request a new specimen from the donor. 

DILUTION/OVER HYDRATION

OverHydration is a less than effective method for chronic drug users and is more effective for users that can abstain from use for a period of time. Over Hydration can be detected using a specimen validity test (SVT).

IMPOSTER COMPUNDS

 

There are legitimate medications and supplements that will react to POCT assays. These compounds do not always cause a false positive, but more likely slow or lighten test line development for a specific assay. The best way to combat these situations is to allow the POCT time to fully develop. Even with 5 or more minutes of development, some imposter compounds can only be ruled out by a certified laboratory.

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