Differentiation of hematuria using a uniquely shaped red cell

Current state of the morphological assessment of urinary erythrocytes in The Netherlands: a nation-wide questionnaire

Background The morphological assessment of urinary erythrocytes (uRBC) is a convenient screening tool for the differentiation of nephrological (dysmorphic) and urological (isomorphic) causes of hematuria. Considering the morphological heterogeneity, this analysis is often perceived as difficult. There is no clear (inter)national consensus and there is a lack of external quality assessment programs. To gain insight into the heterogeneity within and between laboratories, we scrutinized the current state of this analysis in Dutch medical laboratories. Methods The laboratories, affiliated with the Dutch Foundation for Quality Assessment in Medical Laboratories, were invited to participate in a web-based survey, consisting of two questionnaires. The first one provided information about the institution and laboratory organization, and the second explored the variability in the morphological analysis of uRBC on the basis of categorization of 160 uRBC images. Statistical analysis was premised on binomial significance testing and principal component analysis. Results Nearly one third of the Dutch medical laboratories (65/191) with 167 staff members participated in the survey. Most of these laboratories (83%) were an integral part of secondary care. The statistical analysis of the evaluations of the participants in comparison to the consensus (three experts from two different medical laboratories) suggested a great degree of heterogeneity in the agreement. Nearly half of the participants consciously disagreed with the consensus, whereas one fifth demonstrated a random relationship with it. Conclusions In Dutch medical laboratories, results from morphological analysis of uRBC are heterogeneous, which point out the necessity for standardization and harmonization.

Glomerular isolated microscopic hematuria: urinary features and long term follow-up of a selected cohort of patients

BACKGROUND

Isolated microscopic hematuria is a condition characterized by the presence in the urine of an "abnormal" number of erythrocytes in the absence of proteinuria. Several studies have been published on this condition, but with heterogeneous inclusion criteria and variable outcomes at follow-up. In this retrospective study, we describe a selected and homogenous cohort of patients who presented with isolated microscopic hematuria of glomerular origin.

METHODS

We included in the study patients with isolated microscopic hematuria of glomerular origin (> 1 erythrocyte/high power field at 400× and ≥ 40% dysmorphic erythrocytes and/or ≥ 5% acanthocytes and proteinuria ≤ 150 mg/24 h) with a follow-up of > 60 months from the first documentation of microscopic hematuria.

RESULTS

Forty-two patients (M 12, F 30, age at presentation 14-68 years, eGFR < 60 ml/min/1.73 m²: 1 patient) were included. During a medium term follow-up, microscopic hematuria was persistent in 25 patients (59.5%), transiently absent in 17 (40.5%), always glomerular in 16 patients (38.1%), and occasionally non-glomerular in 26 (61.9%); proteinuria, observed in 16 patients (38.1%), was always transient and < 500 mg/24 h. At the end of a follow-up of 181.8 ± 97.9 (median 168) months, only 2 patients (4.8%) had eGFR < 60 ml/min/1.73 m², one of whom had reduced eGFR already at presentation.

CONCLUSIONS

This study on a small but selected and homogeneous cohort of patients with isolated microscopic hematuria of glomerular origin demonstrates that urinary features can transiently change over time and that the renal outcome is good.

Preanalytical requirements of urinalysis

Urine may be a waste product, but it contains an enormous amount of information. Well-standardized procedures for collection, transport, sample preparation and analysis should become the basis of an effective diagnostic strategy for urinalysis. As reproducibility of urinalysis has been greatly improved due to recent technological progress, preanalytical requirements of urinalysis have gained importance and have become stricter. Since the patients themselves often sample urine specimens, urinalysis is very susceptible to preanalytical issues. Various sampling methods and inappropriate specimen transport can cause important preanalytical errors. The use of preservatives may be helpful for particular analytes. Unfortunately, a universal preservative that allows a complete urinalysis does not (yet) exist. The preanalytical aspects are also of major importance for newer applications (e.g. metabolomics). The present review deals with the current preanalytical problems and requirements for the most common urinary analytes.

The pre-analytical challenges of routine urinalysis

An effective diagnostic strategy for urinalysis should be based on standard procedures for collection, transport, sample preparation and analysis. In view of a better reproducibility of the analyses, the pre-analytical requirements become stricter. Various sample methods can cause significant pre-analytical errors. It is a challenge for the laboratory to control the steps in the pre-analytical phase that contribute to pre-analytical variability. To reduce the variability, it is necessary to look at the pre-analytical process as a complete entity, from test ordering to the moment of specimen processing. Clinical laboratories are responsible for the clinical and financial outcome of this phase. In a culture of increasing productivity, lower costs and improving quality, the challenge is to use several tools designed to standardize and optimize urinalysis. Despite advances in the performance of analytic systems, the pre-analytical phase of modern urinalyses has not been studied very thoroughly. This review of the literature lights on different problems in current pre-analytical requirements for particle and test strip analysis of urine samples.

Urine erythrocyte morphology in patients with microscopic haematuria caused by a glomerulopathy

The evaluation of urinary erythrocyte morphology (UEM) has been proposed for patients with isolated microscopic haematuria (IMH) to early orientate the diagnosis towards a glomerular or a nonglomerular disease. However, to date, the role of this test in patients with IMH has very rarely been investigated. Sixteen patients (ten children, six adults) with persistent IMH classified as glomerular on the basis of repeated UEM evaluations (55 urine samples, two to eight per patient) were submitted to renal biopsy. This showed a glomerular disease in 14/16 patients (87.5%) (nine thin basement membrane disease; three Alport syndrome; two other), whereas in two patients, no abnormalities were found. Of four microscopic criteria investigated to define a IMH as glomerular, >80% dysmorphic erythrocytes were not found in any sample, >or=40% dysmorphic erythrocytes alone were seen in seven samples (12.7%), >or=5% acanthocytes alone in 15 samples (27.3%) and erythrocytic casts in six samples (10.9%). There was >or=40% dysmorphic erythrocytes associated with >or=5% acanthocytes in 25 samples (45.5%). Sensitivity and positive predictive values in diagnosing a glomerular haematuria were 59.2% and 90.6%, respectively, for >or=40% dysmorphic erythrocytes, 69.4% and 85% for >or=5% acanthocytes/G1 cells and 12.2% and 100% for erythrocytic casts. Our findings demonstrate that the evaluation of UEM is useful to identify patients with an IMH of glomerular origin.

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.

How to improve the teaching of urine microscopy

BACKGROUND

Urinary microscopy is difficult to teach. This paper describes a 1-day course on urine microscopy, which was based on both theoretical and practical sessions at the microscope, during which real urine samples were examined.

METHODS

The course was based on: a) an introductory presentation with slides on the main components of urinary sediments and their clinical correlates; b) examination of fixed urine samples under the guidance of two experts; and c) the use of two microscopes, each equipped with a co-observation device for up to 15 observers.

RESULTS

Throughout 2005, four courses were held in four Italian towns. Altogether, there were 97 participants (20-27 per course) from 75 laboratories, all graduates with wide but variable experience in the field. During each course, 17-22 urinary sediment components were shown by both bright-field and phase-contrast microscopy and, when indicated, by polarized light. Tests set before and after the course showed a significant improvement (p<0.01) in the identification of erythrocyte subtypes, epithelial cells, fatty components, various types of casts and drug crystals. A questionnaire conducted with participants by phone several months after the course demonstrated that 51.6% and 32.3% of laboratories have introduced or formally requested phase-contrast and polarized-light microscopy, respectively; 45.2% have changed the terminology for urinary epithelial cells; and 87.1% have identified for the first time urinary sediment components that were not recognized or not considered before the course.

CONCLUSIONS

Our course demonstrates that it is possible to improve the teaching of urinary microscopy.

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.

A useful new classification of dysmorphic urinary erythrocytes

BACKGROUND

Among dysmorphic urinary erythrocytes (D cells), G1 cells or doughnut-shaped erythrocytes with one or more blebs are considered to be reliable markers for glomerular diseases. However, although there are many D cells with cytoplasmic color loss and without blebs in the urinary sediment, the significance of these cells is not clear. In this study, we devised a classification system for D cells and examined the relation between these cell types and urinalysis data.

METHODS

We classified D cells into three types (D1, D2, and D3 cells): D1 cells showed a ring-like shape and severe loss of cytoplasmic color with protrusions or blebs; D2 cells showed a doughnut-like shape and moderate cytoplasmic color loss with protrusions or blebs; and D3 cells showed a doughnut-like shape and mild cytoplasmic color loss without protrusions or blebs. We calculated the numbers of D cells of each type in 45 patients with glomerular diseases and in 303 general outpatients. This was done by bright-field microscopy modified for the analysis of urinary sediment, and we also examined the significance of these cell types.

RESULTS

In the 45 patients with glomerular diseases, the numbers of D1, D2, and D3 cells correlated with urine levels of proteinuria and hematuria and numbers of cellular and fatty casts. Numbers of D1 and D2 cells correlated with urine concentrations of albumin and N-acetyl-beta-D-glucosaminidase, and the proportions of D1 and D2 cells in D cells increased with the activity of glomerular diseases classified by urinalysis data. Only the number of D1 cells correlated with the urine concentration of potassium, which may increase in hemolysis. In the 303 outpatients, the sensitivity of D3 cells and D1 and/or D2 cells (G1 cells) was 73% and 46%, respectively, for the detection of glomerular diseases and the specificity was 93% and 99%, respectively.

CONCLUSIONS

These data indicate that the D3 cell is a sensitive marker for glomerular diseases, and that D1 and/or D2 cells are markers for severe glomerular diseases.

Urine cytology in renal glomerular disease and value of G1 cell in the diagnosis of glomerular bleeding

The objectives of the present study were to evaluate the cytology of urine sediments in patients with glomerular diseases, as well as the value of G1 dysmorphic erythrocytes (G1DE) or G1 cells in the detection of renal glomerular hematuria. Freshly voided urine samples from 174 patients with glomerular diseases were processed according to the method used for semiquantitative cytologic urinalysis. G1DEs (distorted erythrocytes with doughnut-like shape, target configuration with or without membranous protrusions or blebs), non-G1DEs (distorted erythrocytes without the above-mentioned morphologic changes), normal erythrocytes (NEs), and renal tubular cells (RTCs) were evaluated. Erythrocytic casts (ECs) were counted and graded as abundant (>1 per high-power field) or rare (1 per 5 high-power fields). G1DE/total erythrocyte ratios were calculated by counting 200 erythrocytes including G1DEs, non-G1DEs, and NEs. Only abundant NEs were found in 13 cases; abundant G1DEs, non-G1DEs, NEs, and no ECs in 95 cases; abundant NEs, non-G1DEs, and ECs and no G1DEs in 31 cases; and abundant NEs, G1DEs and non-G1DEs, and rare ECs in 35 cases. In 130 cases in which G1DEs were present, the G1DE/total erythrocyte ratios varied from 10% to 100%. This parameter was greater or equal to 80%, 50%, 20%, and 10% in 58 (44.6%), 29 (22.3%), 28 (21.5%), and 15 (11.5%) patients, respectively. In all cases, the number of RTCs was within normal limits or slightly increased, and a variable number of non-G1DEs were present in 161 cases. Thus, abundant ECs and/or G1DEs with a G1DE/total erythrocyte ratio of 10-100% proved to be specific urinary markers for renal glomerular diseases.

Urinary microscopy as seen by nephrologists

Urinary microscopy is a diagnostic tool which is largely used by nephrologists. In the opinion of the authors the best results can be achieved when all the aspects concerning this test are properly taken into account. Thus, from the methodological point of view, proper patient guidance, proper urine collection and handling, adequate microscopic equipment, and knowledge of the factors which can influence the results are all necessary. All the elements of clinical importance have to be known, namely, erythrocytes (with their morphological subtypes), leukocytes, tubular cells, uroepithelial cells (both superficial and deep), lipids, casts, crystals, and microorganisms. Then, the urinary findings have to be interpreted and, whenever possible, also combined into urinary profiles (e.g., the nephritic sediment, the nephrotic sediment). This, combined with other laboratory tests, the pathologic findings, and the clinical data, allows for the definition and management of urinary tract diseases.

[Hematuria in the child. Investigation plan in pediatric practice]

The discovery of hematuria in a child should lead the pediatrician to a methodical evaluation of the patient based on an extensive history and comprehensive physical examination. The microscopic examination of the urine is the cornerstone in the evaluation process and may suggest the origin of the hematuria. For instance, red blood cell casts indicate glomerular lesions and rule out the need for further urological examinations. According to the type of hematuria and the associated symptoms, a complete and immediate evaluation is sometimes necessary. This article presents a decisional tree to help the pediatrician to investigate an hematuria and to refer the child to a specialist, when needed.

Asymptomatic microscopic hematuria--is investigation necessary?

Microscopic hematuria is common in asymptomatic adults, but the benefit of screening the general population for blood in the urine has not been established. On the other hand, most studies of referred patients with putatively asymptomatic microscopic hematuria have reported a 2-11% prevalence of urothelial malignancies, leading to the recommendation that all patients with microscopic hematuria be thoroughly investigated. Urinalysis is inexpensive and highly acceptable to the general population, but is neither a sensitive, nor specific test, and has poor predictive value for urothelial malignancies, and nephrological diseases. Furthermore the benefits of early detection of such diseases has not been established. We conclude that screening urinalysis cannot be recommended. Studies are needed to determine which constellation of findings primary physicians use to select patients for referral to centers with urological and nephrological expertise.

Diagnosis of glomerular haematuria: role of dysmorphic red cell, G1 cell and bright-field microscopy

Differentiation between glomerular and non-glomerular haematuria by observation of the changes in red cell morphology using phase-contrast microscopy is a well established technique. However, the method is not widely accepted in clinical practice because of controversy regarding the minimum percentage of dysmorphic red cells required to diagnose glomerular aetiology, as well as the need for specialized microscopes. Recently, a glomerular-specific morphological alteration of red cells has been described, which has the form of a doughnut shape with one or more blebs and which is termed the "G1" cell. In the present double-blind prospective study 250 urine samples were examined without any knowledge of diagnosis. Haematuria was detected in 122 cases. The type of haematuria was characterized by counting dysmorphic cells and G1 cells separately, in each case using a phase-contrast microscope as well as an ordinary bright-field microscope with and without staining of urinary sediments. The results were later correlated with the confirmed diagnosis. The study showed that the G1 cell is more specific than the dysmorphic cell for the diagnosis of glomerular haematuria. Evaluation of both dysmorphic red cells and G1 cells can be done using bright-field microscopy with 100% specificity and sensitivities of 82 and 100%, respectively. It has been concluded that the ordinary bright-field microscope can be used for the diagnosis of glomerular haematuria with an efficiency similar to that of a phase-contrast microscope.

Validity of G1-cells in the differentiation between glomerular and non-glomerular haematuria in children

Urine samples from 100 children and adolescents with micro- or macrohaematuria were investigated using phase contrast microscopy to establish the percentage of G1-cells that could differentiate glomerular from non-glomerular haematuria. The G1-cell is a special form of dysmorphic erythrocyte which seems to be specific for glomerular haematuria. Glomerular haematuria, defined by clinical criteria from biopsy, physical examination, standard laboratory evaluation and family history, was observed in 51 patients (group 1). Non-glomerular haematuria was found in 49 patients (group 2). The latter group had urinary tract infections, urolithiasis, hypercalciuria or haematuria caused by urological operation or diagnostic procedure. The percentage of dysmorphic erythrocytes differed significantly between the two groups studied (42 +/- 3% in group 1 vs. 6 +/- 1% in group 2, mean +/- SEM, P < 0.01); there was also a significant difference in G1-cells (19.4 +/- 1.7% in group 1 vs. 0.6 +/- 0.2% in group 2, mean +/- SEM, P < 0.01). When glomerular haematuria was defined on the basis of > or = 30% dysmorphic erythrocytes by phase contrast microscopy, sensitivity, specificity and efficiency were 71%, 100% and 85%, respectively. When glomerular haematuria was defined on the basis of > or = 5% G1-cells, sensitivity, specificity and efficiency were 100%, 100% and 100%, respectively. The differentiation of glomerular and non-glomerular haematuria in children by determination of G1-cells appears to be more sensitive and efficient than the determination of the percentage of dysmorphic erythrocytes by phase contrast microscopy.

Differentiation of glomerular and non-glomerular hematuria in children by measurement of mean corpuscular volume of urinary red cells using a semi-automated cell counter

Urine samples from 110 children and adolescents with micro- or macrohematuria were compared using phase-contrast microscopy and a semi-automated cell counter to differentiate glomerular from non-glomerular hematuria. Glomerular hematuria, defined by clinical criteria from biopsy and standard chemical evaluation, was observed in 73 patients (group 1): non-glomerular hematuria was found in 37 patients (group 2). The latter group underwent urological operation and had normal urine before operation. Mean corpuscular erythrocyte volume (MCVU) and percent of dysmorphic erythrocytes were determinated. To exclude the influence of mean erythrocyte volume of blood erythrocytes (MCVB), MCVB was determined and additionally the quotient of MCVU/MCVB was calculated (MCVUB). The percentage of dysmorphic erythrocytes differed significantly between the two groups ((75 +/- 13% in group 1 versus 38 +/- 27% in group 2 (mean +/- SD); p < 0.01), MCVU (34.0 +/- 11.1 fl in group 1 versus 55.5 +/- 16.3 fl in group 2; p < 0.01) and MCVUB (0.41 +/- 0.14 in group 1 versus 0.67 +/- 0.20 in group 2; p < 0.01). When glomerular hematuria was defined on the basis of more than 80% dysmorphic erythrocytes, the sensitivity of phase-contrast microscopy was 0.52, specificity versus 0.96 and efficiency 0.64. When glomerular hematuria was defined as < 50 fl MCVU, sensitivity was 0.92, specificity 0.57 and efficiency 0.80 and as < 0.06 MCVUB, sensitivity was 0.89, specificity 0.62 and efficiency 0.80. The correlation coefficient between MCVU and dysmorphic erythrocytes was -0.71 (p < 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)