Can the use of Urea Peroxide (Urea) or Sodium Borate in Rapid Urine Test (RUT) kits cause false positive reactions due to pseudoperoxidase activity?

From the Research

Urea peroxide and sodium borate in rapid urine test kits can cause false positive reactions due to pseudoperoxidase activity, and it is recommended to use alternative formulations that do not contain these compounds to minimize false positives. When performing rapid urine tests, it is essential to select kits specifically designed to minimize false positives from non-urease sources. If using a commercial kit, check the composition and avoid those containing perborates. For in-house preparations, use a simple mixture of urea (2%) in a buffer with an appropriate pH indicator, as suggested by studies on urea and its applications 1.

Key Considerations

• The use of urea peroxide and sodium borate in rapid urine test kits can lead to false positive results due to pseudoperoxidase activity, which can be problematic in clinical settings.
• Alternative formulations that do not contain these compounds can help minimize false positives, as seen in studies on rapid urine test kits and their compositions.
• The presence of blood in the biopsy specimen can also trigger pseudoperoxidase activity, leading to false positives, as hemoglobin has peroxidase-like activity that can cause color changes similar to those produced by urease activity 2.
• Thoroughly rinsing biopsy specimens to remove blood before testing and considering confirming positive results with a secondary method such as histology or PCR can help reduce false positives.

Recommendations

• Use alternative RUT formulations that do not contain urea peroxide and sodium borate to minimize false positives.
• Select kits specifically designed to minimize false positives from non-urease sources.
• Check the composition of commercial kits and avoid those containing perborates.
• Use a simple mixture of urea (2%) in a buffer with an appropriate pH indicator for in-house preparations.
• Be aware of the potential for false positives due to pseudoperoxidase activity and take steps to minimize this risk, such as thoroughly rinsing biopsy specimens and considering secondary confirmation methods.