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

Glomerular Hematuria and the Utility of Urine Microscopy: A Review

Evaluation of hematuria and microscopic examination of urine sediment are commonly used tools by nephrologists in their assessment of glomerular diseases. Certain morphological aspects of urine red blood cells (RBCs) seen by microscopy may help in identifying the source of hematuria as glomerular or not. Recognized signs of glomerular injury are RBC casts or dysmorphic RBCs, in particular acanthocytes (ring-shaped RBCs with protruding blebs). Despite being a highly operator-dependent test, urine sediment examination revealing these signs of glomerular hematuria has demonstrated specificities and positive predictive values ranging between 90%-100% for diagnosing glomerular disease, although sensitivity can be quite variable. Hematuria is a commonly used tool for diagnosing patients with proliferative glomerulonephritis such as IgA nephropathy, antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis, and lupus nephritis, sometimes even as a surrogate for kidney involvement. Studies examining the role for hematuria in monitoring and predicting adverse outcomes in these diseases have shown inconsistent results, possibly due to inconsistent definitions that often fail to consider specific markers of glomerular hematuria such as dysmorphic RBCs, acanthocytes, or RBC casts. A consensus definition of what constitutes glomerular hematuria would help standardize use in future studies and likely improve the diagnostic and prognostic value of hematuria as a marker of glomerulonephritis.

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.

Enhancing the Detection of Dysmorphic Red Blood Cells and Renal Tubular Epithelial Cells with a Modified Urinalysis Protocol

Urinary sediment is used to evaluate patients with possible urinary tract diseases. Currently, numerous protocols are applied to detect dysmorphic red blood cells (RBCs) and renal tubular epithelial cells (RTECs) in urinary sediment. However, distinct protocols are used by nephrologists and medical technologists for specimen concentration and observation, which leads to major discrepancies in the differential counts of formed elements such as dysmorphic RBCs and RTECs and might interfere with an accurate clinical diagnosis. To resolve these problems, we first tested a modified urinalysis protocol with an increased relative centrifuge force and concentration factor in 20 biopsy-confirmed glomerulonephritis patients with haematuria. We successfully improved the recovery ratio of dysmorphic RBCs in clinical specimens from 34.7% to 42.0% (P < 0.001). Furthermore, we confirmed the correlation between counts by the modified urinary protocol and Sysmex UF-1000i urinary flow cytometer (r ≥ 0.898, P < 0.001). A total of 28 types of isomorphic and dysmorphic RBCs were detected using a bright field microscope, with results comparable to those using a standard phase contrast microscope. Finally, we applied Sternheimer stain to enhance the contrast of RTECs in the urinary sediments. We concluded that this modified urinalysis protocol significantly enhanced the quality of urinalysis.

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.

Benefits of the iQ200 automated urine microscopy analyser in routine urinalysis

BACKGROUND

Urine microscopic analysis is hampered by its lack in standardisation and semi-quantitative reports, resulting in limited reliability. Automation of urinalysis could overcome these problems.

METHODS

We compared the performance of the iQ200 with traditional microscopy and strip analysis in routine urinalysis. A total of 1482 routine samples, positive in dipstick testing, were evaluated for erythrocytes, leukocytes, casts, dysmorphic erythrocytes and bacteria using the iQ200 and traditional microscopy. The results of 320 of these samples were linked to underlying urological pathology as well as results from bacterial culturing.

RESULTS

Analytically, the iQ200 surpasses traditional microscopy. The identification of casts and dysmorphic erythrocytes in routine samples improves when using the iQ200, although the sub-classification of casts required well-trained technicians. The auto-classification of particles was least reliable for yeast and bacterial cocci. The quantitative reports, and therefore the use of precise cut-off points allowed earlier and improved detection of urinary tract pathology.

CONCLUSIONS

The performance of the iQ200 is equal to traditional microscopy, but it strongly improves the reliability of urinalysis by standardisation, quantitative reports and improved workflow. From a clinical point of view, renewed attention and improvement of routine urinalysis aids in the efficient detection of renal and urinary tract pathology.

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.

Diagnostic approach in patients with asymptomatic haematuria: efficient or not?

Many patients with asymptomatic haematuria are primarily referred to urological examination. To analyse the efficiency of this strategy, we investigated the diagnostic process in 134 patients with asymptomatic haematuria (91 macroscopic and 43 microscopic) who were referred to our urology department. The frequency of diagnostic procedures was urine culture: 91%, cystoscopy: 87%, intravenous urography: 86%, ultrasound: 73%, examination of urinary sediment: 20%. In 70 patients (52%), a urological diagnosis was made. In the remaining 64 patients, the urinary sediment was examined for the presence of dysmorphic erythrocytes and erythrocyte casts in 17 patients (27%). Signs of glomerular haematuria were found in nine of them (53%). The diagnostic strategy in these patients with asymptomatic haematuria was not discordant from several published algorithms but appeared neither efficacious nor efficient. We estimate that when examination of the urinary sediment would have been performed at the start of work-up, 25% of patients could have spared from extensive urological investigation.

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.

Clinical and laboratory diagnosis of acute renal failure

Acute renal failure (ARF) is defined in general terms as an abrupt decrease in renal function sufficient enough to result in retention of nitrogenous waste and disrupt fluid and electrolyte homeostasis. There is no consensus regarding a quantifiable definition of ARF. Prompt evaluation of ARF is vital because ARF can be the end result of diverse processes which can often be reversed or attenuated through therapy directed at the underlying condition. Evaluation begins with careful review of the patient's history, previous medical records, physical examination, urinalysis, and available laboratory data. Routine urine chemical indices, calculation of the fractional excretion of sodium, and examination of the urine sediment are valuable in characterizing the cause of ARF. When this evaluation fails to yield a diagnosis, further testing may be required to evaluate intravascular volume status or diagnose a systemic disorder or glomerular cause of ARF. Response to therapeutic trials may provide a diagnosis. When a diagnosis cannot be made with reasonable certainty through this evaluation renal biopsy should be considered.

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.

Evaluation of urinary markers in acute renal failure

Acute renal failure continues to be a difficult clinical problem despite developments in dialysis and critical care. Diagnosis of the etiology frequently determines treatment. Urinalysis remains an essential diagnostic tool in the approach to acute renal failure, particularly with the current emphasis on cost-containment and evidence-based medicine. This review focuses on some of the characteristic features in the urinalysis found in different forms of acute renal failure, current developments into the molecular basis for these urinary abnormalities, and new markers on the horizon.