A comparison of urinary albumin-total protein ratio to phase-contrast microscopic examination of urine sediment for differentiating glomerular and nonglomerular bleeding.

BACKGROUND: Hematuria can be classified as either glomerular or nonglomerular, depending on the bleeding source. We recently reported that urinary albumin-total protein ratio is potentially useful for identifying the source of hematuria. STUDY DESIGN: Diagnostic test study. SETTING & PARTICIPANTS: 579 fresh urine specimens with microhematuria (> or =5 red blood cells/high-power field) collected from patients with the source of the hematuria confirmed on histopathologic and/or imaging studies and clinical criteria assessed. INDEX TEST: Each urine specimen was evaluated morphologically by using phase-contrast microscopy and biochemically by using urinary albumin-total protein ratio, albumin-creatinine ratio, and total protein-creatinine ratio. REFERENCE TEST: Each patient had a definitive clinical diagnosis established by means of biopsy (64.4%), imaging studies (21.2%), and routine optimal microscopic examination of urine sediment (14.3%). RESULTS: Of 579 specimens, 329 were obtained from patients with glomerular disease and 250 were obtained from patients with nonglomerular disease. Mean urinary albumin-total protein, albumin-creatinine, and total protein-creatinine ratios for those with glomerular versus nonglomerular diseases were 0.73 +/- 0.11 versus 0.41 +/- 0.14 mg/mg (P < 0.001), 1,110 +/- 1,850 versus 220 +/- 560 mg/g (P < 0.001), and 1,600 +/- 3,010 versus 480 +/- 1,160 mg/g (P < 0.001), respectively. The percentage of patients with greater than 3% glomerular red cells was 83.3% versus 24.8% (P < 0.001). Receiver operating characteristic curve analysis showed that areas under the curve for albumin-total protein ratio, albumin-creatinine ratio, and total protein-creatinine ratio were 0.992, 0.781, and 0.688, respectively (P < 0.001, albumin-total protein versus albumin-creatinine; P < 0.001, albumin-total protein versus total protein-creatinine). At cutoff values of 0.59 mg/mg, 71 mg/g, and 265 mg/g, albumin-total protein ratio, albumin-creatinine ratio, and total protein-creatinine ratio had sensitivities and specificities of 97.3% and 100%, 78.9% and 61.1%, and 68.8% and 62.0% for detecting glomerular disease, respectively. Phase-contrast microscopy had sensitivity of 83.3% and specificity of 75.2% for detecting glomerular disease. LIMITATIONS: Albumin-total protein ratio cannot be used in patients with urinary total protein less than 5 mg/dL (<0.05 g/L). Use of only 1 sample from 1 patient may not be sufficient to obtain definitive results. CONCLUSIONS: Urinary albumin-total protein ratio is much more useful than phase-contrast microscopy for differentiating between glomerular and nonglomerular disease in patients with microscopic hematuria.

Evaluation of hematuria using the urinary albumin-to-total-protein ratio to differentiate glomerular and nonglomerular bleeding.

BACKGROUND: Depending on the etiology and pathophysiology of hematuria, urinary bleeding is classified as glomerular hematuria or nonglomerular hematuria. Nephritis is usually detected by the presence of proteinuria, especially elevated albumin excretion. In this study, we report on the use of the urinary albumin-to-total-protein ratio to accurately differentiate glomerular and nonglomerular bleeding. METHODS: A total of 143 fresh, random urine specimens demonstrating microscopic hematuria (5 or more red blood cells per high-power field) from patients with the source of the hematuria confirmed by histopathology and/or clinical criteria were included in the study. RESULTS: Of the 143 specimens, 104 were from patients diagnosed with glomerular disease and 39 were from patients with nonglomerular disease. Corrected for urine concentration, the mean total-protein-to-creatinine (Cr) and albumin-to-Cr ratios in the glomerular disease group were 1.67 +/- 2.71 g/g Cr and 1.15 +/- 1.77 g/g Cr, respectively (P < 0.001). In the nonglomerular group, the mean total protein-to-Cr and albumin-to-Cr ratios were 0.19 +/- 0.23 g/g Cr and 0.05 +/- 0.06 g/g Cr, respectively (P < 0.001). However, considerable overlap in the ratios among glomerular and nonglomerular disease groups was observed. In contrast, the mean albumin-to-total protein ratios for glomerular and nonglomerular diseases were 0.72 +/- 0.10 and 0.35 +/- 0.17, respectively (P < 0.001). At a cutoff of 0.59, the albumin-to-total-protein ratio demonstrated a sensitivity of 97.1% (101 of 104 cases) in detecting glomerular disease. CONCLUSIONS: The urinary albumin-to-total-protein ratio is potentially a useful index for the differentiation of glomerular and nonglomerular disease in the presence of microscopic hematuria.

[Development of a new method for diagnosing the origin of urinary bleeding by doghnut-shape urinary red blood cells].

Although the presence of acanthocytes (AC) is a reliable indicator of glomerular bleeding, acanthocytes could be observed in only 60% of patients with glomerulonephritis. Therefore, we attempted to develop a new method for diagnosing the origin of urinary bleeding by the morphological characteristics of doughnut-shaped of urinary red blood cells (RBC). In the present study, urine samples from 7 patients with glomerular bleeding and 4 patients with non-glomerular bleeding, and from 35 urine samples of the glomerular bleeding and non-glomerular bleeding-model were examined. The various type of RBC were observed by a phase contrast microscopic examination. The doughnut-shaped RBC were divided into three shapes (namely, smooth, uneven, target-shaped RBC) by individual characteristics. The appearance rate of each shape was calculated, and both outer and inner diameters of doughnut-shaped RBC in the photographs were also measured. Although there was no change in the value of outer diameter of doughnut-shaped RBC between glomerular bleeding and non-glomerular bleeding, the values of inner diameter of doughnut-shaped RBC in non-glomerular bleeding was significantly smaller than those in glomerular bleeding in all shapes. These results strongly suggested that the measurement of inner diameters of doughnut-shaped RBC is one of the useful diagnostic methods to distinguish the origin of urinary bleeding when AC could not be observed.

[Evaluation of a new method for diagnosing the origin of urinary bleeding by the morphological characteristics of urinary red blood cells].

In this study, we attempted to develop a new method for diagnosing the origin of urinary bleeding by the morphological characteristics of urinary red blood cells (RBC). Seventy-five samples were divided into five types by individual features using phase-contrast microscopy. It was revealed that the ratios of type III, namely acanthocytes, and IV, namely donut-shaped RBC, were significantly higher in patients with glomerular bleeding than those with non-glomerular bleeding. Acanthocytes seemed to be specific to glomerular bleeding, but some urinary samples from patients with glomerular bleeding did not show acanthocytes. Therefore, we suggest that the detection of a combination of acanthocytes and donut-shaped RBC in a urine sample is useful for the diagnosis of glomerular bleeding.