Improved Identification of White Blood Cells and Renal Tubular Epithelial Cells in Urine Using Cytology

摘要

Objectives: Conventional automatic identification system to differentiate white blood cells from renal tubular epithelial cells was limited by overlapping parameters and investigation of clear classification of these two cells could be critical to diagnosis and prognosis. Methods: Urine samples from 120 individuals (30 bladder cystitis, 30 glomerular nephritis, 30 pyelonephritis and 30 nephrotic syndrome) were collected. Urine sediments were stained by Sternheimer method and examined by TJYDSXG-1 microscopic cell analysis system including cell size, degree of cytoplasmic staining and nuclear coefficient of variation (CV). Peroxidase chemical staining was also employed to differentiate white blood cells (WBC) and renal tubular epithelial cells (RTEC) in sediments. Results: WBC in urine sediment was (8-13)μm, while (10-16)μm for RTEC, with 36% overlapping of nuclear CV. Peroxidase chemical staining intensity index is 0-4 for WBC and 0-1 for RTEC. Conclusions: Percentage of overlap between WBC and RTEC can be reduced to 7%-13% when Sternheimer staining was combined with peroxidase staining. Urine is a liquid by-product of the body that is secreted by the kidneys through a process called glomerular filtration, tubular reabsorption and excretion. Biochemical components including proteins, glucose, urobilinogen and urobilirubin, and white blood cells (WBC), squamous cell, salt crystallization and others as formed elements in urine, by which alterations were guides to diagnosis of urinary disease and evaluation of renal function. In 1840 urine formed element examination were firstly introduced by Henry Bence Jones, till nowadays automatic urine formed element analyzer. Presently, there are two kinds of urine formed element analyzer according to working principle of cellular components-dependent morphological analysis and flow cytometry, while neither was fulfilled with clinical demand on accuracy and stability [1, 2]. It was suggested that urine formed element examination is still needed confirmation from authoritative diagnostic system and further identification of cellular type. By clinical testing, authors reasoned that the barrier for automatic analyzer to accurately differentiate cellular type in urine lies in criteria of identification. Cells in urine stained by Sternheimer method could be seen clearly and WBC can be further divided into neutrophils, lymphocytes, eosinophils, monocytes, basophils, and degenerative types of these cells. However, cellular type could be mis-classification by the overlapping of cellular size and nucleus morphology among neutrophils, monocytes and renal tubular epithelial cells (RTEC), which cause decreased coincidence of classified result with authoritative diagnostic system. This study, assess cellular type via cellular morphology using Sternheimer staining and peroxidase active of WBC and RTEC from patients with urinary disease.