WHICH OF THESE ARE CAUSES OF FALSE POSITIVE TESTS FOR PROTEINURIA USING A DIPSTICK EVALUATION?(CLICK ALL THAT APPLY)
False positive tests for semiquantitative tests for proteinuria are not uncommon. Patients with small volume of urine with concentrated urine are more likely to have these false positives. A urine with specific gravity of >1.025 and 1+ protein should raise some suspicion for false positive test.
Gross hematuria and pyuria are other potential confounders as they are related to cellular element breakdown leading to proteinaceous components leading to false positive testing.
When urine is highly alkaline, pH>8, dipstick can lead to false positive findings as the buffer component of the indicator dye is possibly overwhelmed by an actual shift in pH. This is usually seen in UTI with urea splitting organisms. Although, a recent rat study showed that the pH didn't matter in terms of urinary proteinuria estimate using dipstick.
Radiographic contrast agents, high urinary levels of penicillins and or cephaosporins and sulfonamide metabolites in urine can result in false positives in the precipitation method of urinary protein detection but not in the dipstick evaluation. Protein precipitation techniques includes precipitation with sufosalicylic acid, heat and acetic acid or concentrated nitric acid.
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