Impacting Factors

Point of Care Test kits (POCT) - Level 1 Certification

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 (temperature)

POCT STORAGE TEMPERATURES​

It is best to store all POCTs at room or moderate temperatures. (between 62-78˚ is ideal). 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

Can cause invalid or false results

Is in very important 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

Can cause false results

Certain donors will borrow urine and attempt to present the borrowed urine as a legitimate donor sample. 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. 

OPENED POCTS (More than 4 hours)

Can case false Non-Negative results

 

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

Can cause false Negatives

Synthetic urine is almost impossible to detect by many traditional laboratories. This is why it is very important to try to identify synthetic urine before sending the sample to the lab for confirmation. In the development of SmartReader, we noticed a common attribute that was appearing on the POCTS scans. We documented a number of specimens that were low volume, high temperature and fully developed. Today, that sample attribute will trigger a SUSPECT - Overheated Sample. Even if you do not use a SmartReader, you can do the same thing. When you encounter a specimen that is 98˚ or warmer, has a lower volume, 30mL or less and has fully developed test and control lines, you should consider requesting a new sample from the donor.

Chemical Disruption

INEFFECTIVE ADULTERANTS

Can cause invalid or false results

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

Can cause false Negatives

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

Can cause false Non-Negatives

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.

END OF LEVEL 1 WORKBOOK

NEED TO REVIEW?

This is the end of the Level 1 Certification workbook. If you would like to review the information again, you can use the links below.

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