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

Exercise 79

The principle of the leukocyte esterase reagent strip test uses a:

A. Peroxidase reaction

B. Double indicator reaction

C. Diazo reaction

D. Dye-binding technique

Step 1 of 2

Leukocyte:

White blood cells (WBC) in blood are called leukocytes.

• They fight against micro-organisms causing infectious disease.

• The principle is diazo reaction.

Procedure:

• In reagent strip reaction, the reagent pad is filled with acid ester to catalyze hydrolysis.

• LE (Leukocyte esterase) in urine reacts with acid ester in reagent pad by catalyzing the hydrolysis to give acid and aromatic compound.

• Aromatic compound joins with diazonium salt in reagent pad to give azodye (purple color).

• LE reaction in reagent strip test requires longest time to produce result.

• Large or trace, moderate, small, and trace, and, 1+, 2+, and 3+ is reported in result.

• The trace readings should be repeated again in a fresh specimen.

Therefore, “Diazo reaction” is the principle for reagent strip for leukocytes. Hence, the correct answer is option.