Which substance can cause a false negative BLOOD result on a dipstick?

Prepare for the CAMLPR Chemistry Test. Enhance your understanding with interactive quizzes, flashcards, and detailed explanations. Boost your confidence and readiness for exam success!

Multiple Choice

Which substance can cause a false negative BLOOD result on a dipstick?

Urine dipstick blood testing uses a peroxidase-like reaction where hemoglobin catalyzes the oxidation of a chromogen by hydrogen peroxide to produce color. Any substance that can interfere with this oxidative step or neutralize the oxidized color can prevent color development, leading to a false negative. Ascorbic acid fits this role well because it is a strong reducing agent. It can neutralize hydrogen peroxide and reduce the oxidized chromogen, stopping the color change even if blood is present. That’s why high levels of vitamin C in urine can mask blood on the dipstick. Bleach and menstrual blood tend to alter results in ways that often produce false positives or invalid tests due to strong oxidative activity or contamination. High specific gravity can affect test timing or concentration but is not a typical cause of a false negative for this test.

Urine dipstick blood testing uses a peroxidase-like reaction where hemoglobin catalyzes the oxidation of a chromogen by hydrogen peroxide to produce color. Any substance that can interfere with this oxidative step or neutralize the oxidized color can prevent color development, leading to a false negative.

Ascorbic acid fits this role well because it is a strong reducing agent. It can neutralize hydrogen peroxide and reduce the oxidized chromogen, stopping the color change even if blood is present. That’s why high levels of vitamin C in urine can mask blood on the dipstick.

Bleach and menstrual blood tend to alter results in ways that often produce false positives or invalid tests due to strong oxidative activity or contamination. High specific gravity can affect test timing or concentration but is not a typical cause of a false negative for this test.

More practice questions