Urinalysis and Body Fluids 6th Edition by Majorie DiLorenzo, Susan Strasinger

Exercise 65

The principle of the reagent strip test for blood is based on the:

A. Binding of heme and a chromogenic dye

B. Peroxidase activity of heme

C. Reaction of peroxide and chromogen

D. Diazo activity of heme

Step 1 of 2

Reagent strip reaction of blood: It is performed to detect blood in urine. The principle is “heme peroxidase” activity.

Procedure:

• The reagent strip has peroxide and tetramethylbenzidine in testing area for blood.

• Hemoglobin and myoglobin’s heme component reacts with tetramethylbenzidine (chromogen) to give oxidized chromogen in the color of green-blue.

• Color range from negative yellow ->green->positive green->blue are formed in the occurrence of free myoglobin or hemoglobin.

• 5 red blood cells per micro liter can be detected in reagent strip.

• 1+, 2+, 3+ or Trace, small, moderate, and large terms are used to report the result.

Therefore, the principle of reaction in reagent strip for blood is “heme peroxidase activity”. Hence, the correct answer is option.