Determination of leukocytes in urine

Chemical determination of leukocytes with a diagnostic strip is based on the detection of esterases that are abundant in granulocytes . Granulocyte esterases catalyze the hydrolysis of indoxyl ester to free indoxyl. The indoxyl then reacts with the stable diazonium salt to form the appropriate azo dye. In the case of a negative reaction, the zone turns cream yellow; in the case of a positive reaction, it changes to a pink to purple hue.

Chemical examination of leukocytes does not replace microscopic examination . On the other hand, it is possible to detect lysed leukocytes (eg in hypotonic urine ) in this way, which is not possible with microscopic examination.

Leukocyturia is a symptom of inflammation of the kidneys or urinary tract. The cause of most positive findings is a bacterial infection of the urinary tract . In case of a positive leukocyte finding, it is recommended to supplement the examination of proteinuria , hematuria , nitrituria , examination of urinary sediment and further microbiological examination .