Shape Of Red Blood Cells Research Articles

Red Blood Cells Initiate Leukocyte Rolling in Postcapillary Expansions: A Lattice Boltzmann Analysis

Leukocyte rolling on the vascular endothelium requires initial contact between leukocytes circulating in the blood and the vessel wall. Although specific adhesion mechanisms are involved in leukocyte-endothelium interactions, adhesion patterns in vivo suggest other rheological mechanisms also play a role. Previous studies have proposed that the abundance of leukocyte rolling in postcapillary venules is due to interactions between red blood cells (RBCs) and leukocytes as they enter postcapillary expansions, but the details of the fluid dynamics have not been elucidated. We have analyzed the interactions of red and white blood cells as they flow from a capillary into a postcapillary venule using a lattice Boltzmann approach. This technique provides the complete solution of the flow field and quantification of the particle-particle forces in a relevant geometry. Our results show that capillary-postcapillary venule diameter ratio, RBC configuration, and RBC shape are critical determinants of the initiation of cell rolling in postcapillary venules. The model predicts that an optimal configuration of the trailing red blood cells is required to drive the white blood cell to the wall.

Effect of Trauma-Hemorrhagic Shock on Red Blood Cell Deformability and Shape

Previous work in our laboratory has demonstrated a decrease in red blood cell (RBC) deformability in sepsis. This has not been studied following hemorrhagic shock. We tested the hypotheses that hemorrhagic shock, associated with soft tissue trauma, leads to decreased RBC deformability and that this is related to alterations in the resting shape of the RBC. Elongation index (EI), a measure of RBC deformability, was determined over a range of shear stresses from 0.3 to 30 Pa in 26 male rats before and at various times after 90 min of hemorrhagic shock. RBC resting shape was determined by scanning electron microscopy. The data demonstrate that EI decreased significantly at the end of shock (before resuscitation), and remained below normal throughout the 6-h postshock period. Eight of the 26 animals decompensated during shock, requiring return of a portion of the shed blood to maintain a mean arterial pressure of 30-40 mmHg. Four of eight decompensated animals died before the end of the study period, compared with none of the compensated rats. The decompensated rats had significantly lower EI at 0.3 Pa by the end of the shock period (0.050 +/- 0.009) than the compensated shock group (0.058 +/- 0.006; P < 0.05). RBC shape alterations were first demonstrated at the end of the shock period and persisted throughout the 6-h postshock resuscitation period. These data indicate that trauma and hemorrhagic shock cause RBC shape alterations and a significant decrease in RBC deformability, which becomes manifested during the shock period and persists for at least 6 h postshock. Additionally, a direct relationship appears to exist between the magnitude of the physiologic insult and the degree of RBC damage.

Dynamical clustering of red blood cells in capillary vessels.

We have modeled the dynamics of a 3-D system consisting of red blood cells (RBCs), plasma and capillary walls using a discrete-particle approach. The blood cells and capillary walls are composed of a mesh of particles interacting with harmonic forces between nearest neighbors. We employ classical mechanics to mimic the elastic properties of RBCs with a biconcave disk composed of a mesh of spring-like particles. The fluid particle method allows for modeling the plasma as a particle ensemble, where each particle represents a collective unit of fluid, which is defined by its mass, moment of inertia, translational and angular momenta. Realistic behavior of blood cells is modeled by considering RBCs and plasma flowing through capillaries of various shapes. Three types of vessels are employed: a pipe with a choking point, a curved vessel and bifurcating capillaries. There is a strong tendency to produce RBC clusters in capillaries. The choking points and other irregularities in geometry influence both the flow and RBC shapes, considerably increasing the clotting effect. We also discuss other clotting factors coming from the physical properties of blood, such as the viscosity of the plasma and the elasticity of the RBCs. Modeling has been carried out with adequate resolution by using 1 to 10 million particles. Discrete particle simulations open a new pathway for modeling the dynamics of complex, viscoelastic fluids at the microscale, where both liquid and solid phases are treated with discrete particles. Figure A snapshot from fluid particle simulation of RBCs flowing along a curved capillary. The red color corresponds to the highest velocity. We can observe aggregation of RBCs at places with the most stagnant plasma flow.

Bifurcating critical points of bending energy under constraints related to the shape of red blood cells

Considered is a variational problem for the bending energy of closed surfaces under the prescribed area and surrounding volume. Minimizers of this problem are interpreted as surfaces modeling the shape of red blood cells. We give a rigorous proof of the existence of a one-parameter family of critical points bifurcating from the sphere and study their stability/instability. In particular, for a few branches of critical points, we compute the exact values of the index and the nullity of critical points.

Erythroid Expression of the Human α-Spectrin Gene Promoter Is Mediated by GATA-1- and NF-E2-binding Proteins

alpha-Spectrin is a highly expressed membrane protein critical for the flexibility and stability of the erythrocyte. Qualitative and quantitative defects of alpha-spectrin are present in the erythrocytes of many patients with abnormalities of red blood cell shape including hereditary spherocytosis and elliptocytosis. We wished to determine the regulatory elements that determine the erythroid-specific expression of the alpha-spectrin gene. We mapped the 5' end of the alpha-spectrin erythroid cDNA and cloned the 5' flanking genomic DNA containing the putative alpha-spectrin gene promoter. Using transfection of promoter/reporter plasmids in human tissue culture cell lines, in vitro DNase I footprinting analyses, and gel mobility shift assays, an alpha-spectrin gene erythroid promoter with binding sites for GATA-1- and NF-E2-related proteins was identified. Both binding sites were required for full promoter activity. In transgenic mice, a reporter gene directed by the alpha-spectrin promoter was expressed in yolk sac, fetal liver, and erythroid cells of bone marrow but not adult reticulocytes. No expression of the reporter gene was detected in nonerythroid tissues. We conclude that this alpha-spectrin gene promoter contains the sequences necessary for low level expression in erythroid progenitor cells.

Shape behavior of lipid vesicles as the basis of some cellular processes.

The basic principles that govern the shape behavior of phospholipid vesicle shapes are discussed. The important membrane parameters of the system are defined by presenting the expressions for the relevant contributions to the system's mechanical energy. In the description of the rather unique shape behavior of lipid vesicles, the emphasis is on providing a qualitative understanding of the dependence of vesicle shape on the parameters of the system. The vesicle shape behavior is then related to biologically important phenomena. Some examples are given of how the results of the shape behavior of lipid vesicles can be applied to the analysis of cellular systems. Red blood cell shape and shape transformations, vesicle fission and fusion processes, and the phenomenon of cellular polarity are considered. It is reasoned that the current biological processes that involve changes of membrane conformation may have their origin in the general shape behavior of closed lamellar membranes.

Blood flow and red blood cell deformation in nonuniform capillaries: effects of the endothelial surface layer.

A theoretical model is used to examine the mechanics of red blood cell (RBC) motion in nonuniform capillaries. The model includes effects of the endothelial surface layer (ESL), which is a layer of macromolecules adjacent to the endothelium and which impedes plasma flow. The motion of an RBC traversing a capillary with diameter varying sinusoidally between 5.4 microm and 7.4 microm is simulated numerically. The ESL is assumed to be 0.7-microm wide and deformable. Axisymmetric RBC shapes are assumed. Lubrication theory is used to analyze the motion of plasma around the RBC and through the ESL. In a nonuniform capillary with no ESL, moving RBCs undergo large transient deformations and predicted flow resistance is substantially higher than in a uniform capillary with the same mean diameter. The presence of a deformable ESL reduces the transient fluid shear stresses and deformations experienced by RBCs traversing a nonuniform capillary. With an ESL, the increase in flow resistance resulting from nonuniformity is less than twofold versus three- to fourfold with no ESL in vessel geometries with the same ESL-free luminal region. The presence of the ESL reduces the impact of capillary irregularity on flow resistance and may protect RBCs traversing irregular capillaries from damage due to large, rapidly fluctuating external stresses.

Copper deficiency in Creole goat kids.

Serum copper determination is important to confirm hypocupremia. Twenty healthy kids constituted the Control Group, and sixteen kids with symptoms of copper deficiency, the Problem Group. Animals from the Problem Group showed a low number of red blood cells (RBC) and variations in RBC size and shape. The values found for hemoglobin and mean corpuscular hemoglobin (MCH) in the Control Group were 10.42 +/- 1.34 g.dL(-1) and 33.07 +/- 1.11 g.dL(-1) respectively, while the levels of the Problem Group were 7.95 +/- 1.21 g.dL(-1) and 29.45 +/- 0.78 g.dL(-1), respectively. The kids from the Problem Group presented an important increase in monocytes, neutrophiles and leukocytes; precursor cells of the neutrophile were also observed. The anemia of these animals was hypochromic and macrocytic. Our results indicate that Creole kids with serum copper levels > 450 microg.L(-1) improved after treatment with copper glycinate. The six goats with cupremia < 450 microg.mL(-1) were unable to improve their deficiency and died.

Echinocyte Shapes: Bending, Stretching, and Shear Determine Spicule Shape and Spacing

We study the shapes of human red blood cells using continuum mechanics. In particular, we model the crenated, echinocytic shapes and show how they may arise from a competition between the bending energy of the plasma membrane and the stretching/shear elastic energies of the membrane skeleton. In contrast to earlier work, we calculate spicule shapes exactly by solving the equations of continuum mechanics subject to appropriate boundary conditions. A simple scaling analysis of this competition reveals an elastic length Λ el, which sets the length scale for the spicules and is, thus, related to the number of spicules experimentally observed on the fully developed echinocyte.

A213 赤血球の形状と膜の残留応力との関係

A213 赤血球の形状と膜の残留応力との関係

Blood Flow and Red Blood Cell Deformation in Nonuniform Capillaries: Effects of the Endothelial Surface Layer

Objective: A theoretical model is used to examine the mechanics of red blood cell (RBC) motion in nonuniform capillaries. The model includes effects of the endothelial surface layer (ESL), which is a layer of macromolecules adjacent to the endothelium and which impedes plasma flow. Methods: The motion of an RBC traversing a capillary with diameter varying sinusoidally between 5.4 µm and 7.4 µm is simulated numerically. The ESL is assumed to be 0.7-µm wide and deformable. Axisymmetric RBC shapes are assumed. Lubrication theory is used to analyze the motion of plasma around the RBC and through the ESL. Results: In a nonuniform capillary with no ESL, moving RBCs undergo large transient deformations and predicted flow resistance is substantially higher than in a uniform capillary with the same mean diameter. The presence of a deformable ESL reduces the transient fluid shear stresses and deformations experienced by RBCs traversing a nonuniform capillary. With an ESL, the increase in flow resistance resulting from nonuniformity is less than twofold versus three- to fourfold with no ESL in vessel geometries with the same ESL-free luminal region. Conclusions: The presence of the ESL reduces the impact of capillary irregularity on flow resistance and may protect RBCs traversing irregular capillaries from damage due to large, rapidly fluctuating external stresses.

Artificial translocases

The distribution of different types of phospholipids in a cell's lipid bilayer is controlled by translocase enzymes. A team of chemists in the USA have reported how synthetic artificial translocases can be used to influence this distribution to change the shape and surface properties of red blood cells (Journal of the American Chemical Society, 4 July). The artificial enzymes stick to the phospholipids’ charged head groups, making them more soluble in the lipophilic interior of the bilayer. The researchers describe how a deformed ‘spiky’ form of an erythrocyte, known as an echinocyte, was reverted to its normal disc-like shape by treatment with the translocase. They believe that they will now be able to target specific phospholipids and move them between different regions of the bilayer at will, to produce cells with tailored biological properties. MJD

Morphologic changes of red blood cells during hemorrhagic shock replicate changes of aging.

Blood loss leads to the reduction in vitality of red blood cells (RBCs). However, the changes in morphology at different stages of hemorrhagic shock have not been studied. Thus, the aim of this study was to identify and quantitate the sequence of morphological changes in RBCs during hemorrhage. This study was performed on 15 adult inbred dogs. Blood samples were taken before hemorrhage, when the mean arterial pressure reached 40 mm Hg (initial stage of shock), and at a mean arterial pressure level of 20 mm Hg (decompensated stage of shock). The volume of blood removed averaged 33.6+/-8.9 and 55.1+/-6.9 mL/kg, respectively. Evaluation of RBC morphology was performed by computerized light microscopic morphometry and scanning electron microscopy. At the early stage of hemorrhage the number of "young-appearing" RBCs with large visible surface areas (41-50 microm2) increased from 17.7%+/-3.1% to 26.6%+/-3.5% (P < 0.05). Concomitantly, the number of "old-appearing" RBCs with small visible surface area (20-30 microm2) significantly decreased from 5.3%+/-2.7% to 2.7%+/-2.3% (P < 0.01). At the stage of decompensated blood loss, the opposite phenomenon was observed. The number of "old-appearing" RBCs increased to 8.2%+/-1.1% (P < 0.01), whereas the number of "young-appearing" RBCs decreased to 12.3%+/-4.2% (P< 0.01). The changes in visible surface area of RBCs was accompanied by significant alterations in their shape. The percentage of abnormal shaped RBCs increased from 8.9%+/-1.1% before the hemorrhage to 36.4%+/-5.8% at the stage of decompensated hemorragic shock (P < 0.01). Thus, during the late decompensated stage of hemorrhagic shock, RBCs assume shape and surface area changes that are similar to those seen in aging. These changes in RBC size and shape may be due to the effects of shock-induced oxidative stress.

The clinical consequences of the red cell storage lesion.

W E ARE NOW ENTERING the second century in which human blood has been stored for transfusion. In the last 2 decades of the last century, we witnessed a dramatic shift ''1 in which a product once regarded as one of the great advances in modern medicine ''2 was now viewed as potentially harmful. Precipitated by the identification of transfusion-transmitted infections, this paradigm shift has led to a reexamination of the quality of stored blood for transfusion. In this context, contaminating leukocytes, which were an accepted part of red blood cell (RBC) transfusion, have now been implicated in alloimmunization, graft-versus-host disease, cytomegalovirus transmission, and immunomodulation. 3 Another recognized biologic phenomena associated with RBC storage includes the induction of the storage lesion, which can be defined as a series of biochemical and biomechanical changes in the red cell occurring during preservation that reduces subsequent in vivo survival and function. Our understanding of the mechanisms involved in these changes is incomplete, but recent clinical trials and animal experiments have raised fundamental questions about the putative efficacy of stored blood. A large randomized trial comparing a liberal with a conservative transfusion strategy in the critically ill yielded the surprising result that lowering the hemoglobin threshold for RBC transfusions is not only safe but may be associated with reduced mortality. 4 Two studies have suggested that morbidity or mortality may increase with the duration of RBC storage before transfusion. 5,6 In light of these recent findings, we reexamine storage-related changes in RBC shape in relation to posttransfusion survival and RBC function. The experimental data from animal models will be discussed along with recent clinical trials in transfusion medicine, speculating on a possible association between storage-related changes and adverse clinical consequences of transfusing blood.

Quantification of red blood cells using atomic force microscopy

For humans the sizes and shapes of their red blood cells are important indicators of well being. In this study, the feasibility of using the atomic force microscope (AFM) to provide the sizes and shapes of red blood cells has been investigated. An immobilisation procedure has been developed that enabled red blood cells to be reliably imaged by contact AFM in air. The shapes of the red blood cells were readily apparent in the AFM images. Various cell quantification parameters were investigated, including thickness, width, surface area and volume. Excellent correlation was found between the AFM-derived immobilised mean cell volume (IMCV) parameter and the mean cell volume (MCV) parameter used in current haematological practice. The correlation between MCV and IMCV values has validated the immobilisation procedure by demonstrating that the significant cell shrinkage that occurs during immobilisation and drying does not introduce quantification artifacts. Reliable IMCV values were obtained by quantifying 100 red blood cells and this typically required 3–5 AFM images of 100 μm×100 μm area. This work has demonstrated that the AFM can provide in a single test the red blood cell size and shape data needed in the assessment of human health.

Rat erythrocyte morphological changes after gavage dosing with 2-butoxyethanol: a comparison with the in vitro effects of butoxyacetic acid on rat and human erythrocytes.

Rats exposed to 2-butoxyethanol (2-BE) develop hemolysis preceded by red blood cell swelling and shape changes. In this study effects on red blood cell morphology of dosing rats with 2-BE by gavage were compared with the effects of incubation of rat erythrocytes in vitro with the principal metabolite of 2-BE, butoxyacetic acid (BAA). Morphology was assessed by bright-field and phase microscopy of Wright's stained blood smears and glutaraldehyde-fixed cells suspended in plasma or buffer. In vivo exposure to 2-BE resulted in stomatocytosis and spherocytosis in blood smears and cup-shaped cells and spherocytosis in the fixed samples. In vitro incubation with BAA produced erythrocytes with cup shapes, spherocytosis and red blood cell ghosts in fixed samples. The stomatocytes observed in the blood smears appear to be the morphological equivalents of the cup-shaped cells observed in fixed samples. A variable degree of echinocytosis was observed in blood smears from animals exposed to 2-BE and in the in vitro experiments with BAA. Stomatocytes, cup-shaped cells, and spherocytes are the principal morphological features of erythrocytes from rats exposed to 2-BE or in vitro exposure to BAA. In comparison, human red blood cells incubated with up to 2.0 mM BAA exhibited none of the morphological changes observed in rat erythrocytes. 2-Butoxyethanol in vivo and BAA in vitro cause similar changes in rat red blood cell morphology, adding further evidence to support the primary role of BAA in the hemolytic effect of 2-BE exposure in the rat.

Influence of nitrovasodilators and endothelin-1 on rheology of human blood in vitro.

1. The shear stress of flowing blood profoundly influences the release of endothelium-dependent vasodilative and constrictive factors. Conversely, the influence of these mediators such as nitric oxide (NO) or endothelin-1 (ET-1) on blood rheology remains elusive. In the present study the influence of nitrovasodilators and ET-1 on red blood cell (RBC) shape and whole blood viscosity were investigated. 2. Incubation of whole blood with sodium-nitroprusside (SNP, 10-5 - 10-2 M), glyceryl trinitrate (GTN, 0.0001 - 0.1 mg mL-1), S-nitroso-N-acetylpenicillamine (SNAP, 10-6 - 10-3 M), and the active metabolite of molsidomine (SIN-1, 10-6 - 10-3 M), but not molsidomine (10-6 - 10-3 M), resulted in significantly increased amounts of methaemoglobin, indicating a relevant interaction with RBCs. Treatment with SNP at 10-2 M induced a marked echinocytosis (morphological index: 2.23+/-0.98 vs -0.17+/-0.10; P<0.001) and increased blood viscosity (haematocrit 45%) at a high shear rate of 94.5 s-1 (6.46+/-0.60 vs 5.07+/-0.35 mPa.s; P<0.01) and a low shear rate of 0.1 s-1 (88.6+/-36.8 vs 42.1+/-11.7 mPa.s; P<0.01). Echinocytosis was probably due to cyanide accumulation. SIN-1 at 10-3 M slightly decreased high shear viscosity (4.88+/-0.28 vs 4. 95+/-0.30 mPa.s; P<0.05). SNAP at 10-3 M slightly increased both high (5.14+/-0.23 vs 5.05+/-0.24 mPa.s; P<0.01) and low shear (53.9+/-7.2 vs 51.2+/-5.9 mPa.s; P<0.05) viscosity. Molsidomine and GTN failed to influence whole blood viscosity. ET-1 (10-9 - 10-6 M) had no effect on RBC shape and viscosity. 3. We conclude that the most important modulators of vascular tone, NO and ET-1, do not affect RBC shape and blood viscosity, which is important from both a physiological and a pharmacological point of view.

Effects of salicylic acid derivatives on red blood cell membranes.

Salicylamide, sodium salicylate and acetylsalicylic acid are salicylic acid derivates. They differ in their substitution on the benzene ring and may have different effects on membranes. Red blood cells were used as a prototypical cellular system regarding drug mediated plasma bilayer effects. Established photometric methods sensing tiny changes of red blood cell morphology at rest (red blood cell shape) and at very low shear forces (red blood cell stiffness, red blood cell relaxation time) were applied. The derivative induced effects were detected in a time- and dose-dependent manner. Salicylamide induced a most pronounced echinocytic shape at 5 mM. The shape effect was smaller above as well as below 5 mM. Sodium salicylate induced echinocytes with increasing concentrations showing a saturation above 10 mM. In contrast, the shape was not affected by acetylsalicylic acid. All shape changes occurred within 2 min, and were reversible. The above tendencies were in parallel to a slight red blood cell stiffening. The relaxation time continuously increased with increasing concentrations in both salicylamide and sodium salicylate, with salicylamide always acting stronger. Acetylsalicylic acid again showed no effect. We hypothesize that the observed effects of sodium salicylate and salicylamide are due to their phenolic character mediating a molecular hydrophobicity. According to the bilayer couple hypothesis this would lead to an insertion into the red blood cells outer plasma bilayer leaflet. The extension induced here would cause a positive membrane bending leading to echinocytic shapes and the observed loss of red blood cell fluidity. In contrast, the hydrophilic aspirin would penetrate and thus not affect the red blood cell plasma membrane.

Membrane active lipids in remnant lipoproteins cause impairment of endothelium-dependent vasorelaxation.

We have recently found that remnant lipoproteins (RLPs) and their lipid fractions impair endothelium-dependent vasorelaxation (EDR). This study was aimed at clarifying mechanisms responsible for RLP-induced endothelial dysfunction in isolated rabbit aortas. RLPs were isolated from plasma in hyperlipidemic subjects by use of the immunoaffinity gel mixture of anti-ApoA1 and anti-ApoB100 monoclonal antibodies and ultracentrifugation. Organ chamber experiments showed that EDR impairment was restored by addition of reduced glutathione (GSH) or N-acetylcysteine, antioxidants, into the incubation buffer containing isolated rabbit aortas and RLPs (0.75 mg of triglyceride/mL). Furthermore, the incubation of isolated human red blood cells (RBCs) with RLP and its lipids converted the normal shape of RBCs to echinocytes, but coincubation with antioxidants suppressed the RLP-induced RBC transformation, suggesting that they exerted oxidative damage on RBC surface membranes. Studies with HPLC and the postcolumn chemiluminescence method showed that RLPs contain a substantial amount of phosphatidylcholine hydroperoxides. Peroxidized phosphatidylcholine also impaired EDR and had echinocytogenic action, both of which were suppressed by N-acetylcysteine. RLPs isolated from the plasma of patients under treatment with alpha-tocopherol, an antioxidant, had a lower level of phosphatidylcholine hydroperoxides (15% of the amount in nontreated patients), which was associated with a lack of the inhibitory action on EDR and with lesser effect on RBC transformation. Oxidative damage caused by lipid components in RLPs, especially peroxidized phospholipids, deteriorates cell surface membrane and may be at least partly responsible for RLP-induced impairment of EDR.

THE VALUE OF COMPARATIVE VOLUMETRIC ANALYSIS OF URINARY AND BLOOD ERYTHROCYTES TO LOCALIZE THE SOURCE OF HEMATURIA

Purpose We evaluate comparative volumetric analysis of blood and urinary red blood cells (RBCs) to identify the source of hematuria. Comparative volumetric analysis is defined as the difference between mean corpuscular erythrocyte volume in peripheral blood (MCVB) diluted in urine supernatant after centrifugation and mean corpuscular volume of urinary erythrocytes (MCVU). The potential of MCVB-MCVU to distinguish the origin of hematuria is compared to MCVU alone. The fundamental hypothesis is that RBCs that can go through the glomerulus will be smaller than those from the collecting system or lower urinary tract, thus having a smaller MCVU and larger difference between MCVB and MCVU. Materials and Methods A prospective detailed urological evaluation was performed on 210 patients with glomerular or nonglomerular hematuria detected by urinary sediment, clinical radiological evaluation, endoscopy, cytology, and sometimes bladder or renal biopsy. After evaluation 24 cases with an uncertain source of hematuria were excluded from study. Specialized urinalysis, volumetric analysis and clinical investigation were performed in a blind fashion. MCVU and MCVB-MCVU were registered for every patient. The Technicon* H-3 system with angle laser scattering dual system allowed measurement of mean corpuscular volume in a minimal number of RBCs, and resuspension of RBC pellets in the same urinary supinate avoided effects of osmolarity and pH on RBC size and shape. Reproducibility in assessing the index was tested in 50 cases in which comparative volumetric analysis was repeated on 2 consecutive days. Unpaired t test was performed, and a threshold value of MCVB-MCVU with maximum sensitivity and specificity to detect glomerular hematuria was identified. The potential of urinary and comparative volumetric analysis to distinguish the source of hematuria was evaluated and compared by receiver operating characteristics curve analysis. Results Hematuria was nonglomerular in 53 (28.4%) and glomerular in 133 (71.6%) patients. Mean MCVB-MCVU was significantly different for nonglomerular (0.6 fl.) and glomerular (30.5 fl.) sources (p < 0.0001). There was a correlation between repeat independent measures of MCVU and MCVB-MCVU. The highest positive predictive value to detect a glomerular origin is desirable so that unnecessary investigation can be obviated without the risk of missing a nonglomerular source. With a limit of 16 fl. specificity and positive predictive value were 98 and 99%, respectively. Receiver operating characteristics curve analysis to localize the source of hematuria revealed significant differences in favor of comparative volumetric analysis versus urinary volumetric analysis alone. Conclusions MCVB-MCVU using the Technicon H-3 system is a useful noninvasive and accurate method to locate the source of hematuria. A value of 16 fl. or greater practically rules out a nonglomerular origin and obviates further urological investigation. We have incorporated this investigation in our diagnostic algorithm for hematuria.