SERUM HYPERVISCOSITY SYNDROME

[Serum hyperviscosity syndrome: Update 2024]

Seric hyperviscosity syndrome is a medical emergency linked to hyperproteinemia. The clinical diagnosis hinges on a triad of symptoms: mucosal hemorrhages, visual disturbances, and neurological disorders, observed in the most severe cases. Diagnosis is swiftly confirmed through an urgent fundoscopic examination. Therapeutic plasma exchange is the primary treatment for severe cases or following confirmation by fundoscopy. Laboratory tests predominantly identify the syndrome's etiology, with Waldenström's macroglobulinemia (characterized by a marked IgM peak) being the most common cause, followed by multiple myeloma and cryoglobulinemias. To prevent recurrence, targeted treatment of the underlying cause is implemented following plasma exchange sessions.

Management of hematological patients requiring emergency chemotherapy in the intensive care unit

Hematological malignancies may require rapid-onset treatment because of their short doubling time, notably observed in acute leukemias and specific high-grade lymphomas. Furthermore, in targeted onco-hematological scenarios, chemotherapy is deemed necessary as an emergency measure when facing short-term, life-threatening complications associated with highly chemosensitive hematological malignancies. The risks inherent in the disease itself, or in the initiation of treatment, may then require admission to the intensive care unit (ICU) to optimize monitoring and initial management protocols. Hyperleukocytosis and leukostasis in acute leukemias, tumor lysis syndrome, and disseminated intravascular coagulation are the most frequent onco-hematological complications requiring the implementation of emergency chemotherapy in the ICU. Chemotherapy must also be started urgently in secondary hemophagocytic lymphohistiocytosis. Tumor-induced microangiopathic hemolytic anemia and plasma hyperviscosity due to malignant monoclonal gammopathy represent infrequent yet substantial indications for emergency chemotherapy. In all cases, the administration of emergency chemotherapy in the ICU requires close collaboration between intensivists and hematology specialists. In this review, we provide valuable insights that aid in the identification and treatment of patients requiring emergency chemotherapy in the ICU, offering diagnostic tools and guidance for their overall initial management.

Review of Hematology-Oncology Emergencies for Internal Medicine Residents

The prevalence of cancer continues to grow globally every year. With therapeutic advances over the recent decades, the prevalence of individuals living with cancer continues to increase. Internal medicine residents can see patients admitted to the hospital for cancer-related emergencies. Early identification and appropriate management of these emergencies have been shown to improve mortality and morbidity. In this article, we aim to review the recent updates in the management of commonly encountered oncologic emergencies in the practice of internal medicine residents. This review will cover spinal cord compression, superior vena cava syndrome, tumor lysis syndrome, hypercalcemia, pericardial tamponade, hypoglycemia, hyponatremia, bowel obstruction, increased intracranial pressure, leukostasis, hyperviscosity syndrome, neutropenic fever, and hypersensitivity reactions.

Hyperviscosity syndromes; hemorheology for physicians and the use of microfluidic devices

PURPOSE OF REVIEW

Hyperviscosity syndromes can lead to significant morbidity and mortality. Existing methods to measure microcirculatory rheology are not readily available and limited in relevance and accuracy at this level. In this review, we review selected hyperviscosity syndromes and the advancement of their knowledge using microfluidic platforms.

RECENT FINDINGS

Viscosity changes drastically at the microvascular level as the physical properties of the cells themselves become the major determinants of resistance to blood flow. Current, outdated viscosity measurements only quantify whole blood or serum. Changes in blood composition, cell number, or the physical properties themselves lead to increased blood viscosity. Given the significant morbidity and mortality from hyperviscosity syndromes, new biophysical tools are needed and being developed to study microvascular biophysical and hemodynamic conditions at this microvascular level to help predict those at risk and guide therapeutic treatment.

SUMMARY

The use of 'lab-on-a-chip' technology continues to rise to relevance with point of care, personalized testing and medicine as customizable microfluidic platforms enable independent control of many in vivo factors and are a powerful tool to study microcirculatory hemorheology.

Therapeutic Plasma Exchange: For Cancer Patients

Therapeutic plasma exchange is used as a trial method for the treatment of cancer patients. Therapeutic plasma exchange uses in vitro technology to remove pathogenic factors in the plasma, returning the replacement and remaining components to the patient to facilitate cure. In the effort to explore new methods of cancer treatment, the introduction of therapeutic plasma exchange brings new hope for cancer treatment; however, the current evidence supporting therapeutic plasma exchange is controversial, and most of the evidence comes from observational studies, lacking large prospective randomized trials. Therefore, this review attempts to focus on the main indications of therapeutic plasma exchange for the treatment of tumors and their complications, including hematological tumors (multiple myeloma cast nephropathy and hyperviscosity syndrome), nervous system tumors (myasthenia gravis associated with thymoma, paraneoplastic neurological syndrome, Lambert–Eaton myasthenia syndrome, and anti-N-methyl-D-aspartate receptor encephalitis), overdose of chemotherapy drugs. In addition, the issues of side-effects and safety in the use of therapeutic plasma exchange are also discussed. However, well-designed prospective trials are needed to better define the role of therapeutic plasma exchange in cancer.

Detailed Structure and Pathophysiological Roles of the IgA-Albumin Complex in Multiple Myeloma

Immunoglobulin A (IgA)-albumin complexes may be associated with pathophysiology of multiple myeloma, although the etiology is not clear. Detailed structural analyses of these protein-protein complexes may contribute to our understanding of the pathophysiology of this disease. We analyzed the structure of the IgA-albumin complex using various electrophoresis, mass spectrometry, and in silico techniques. The data based on the electrophoresis and mass spectrometry showed that IgA in the sera of patients was dimeric, linked via the J chain. Only dimeric IgA can bind to albumin molecules leading to IgA-albumin complexes, although both monomeric and dimeric forms of IgA were present in the sera. Molecular interaction analyses in silico implied that dimeric IgA and albumin interacted not only via disulfide bond formation, but also via noncovalent bonds. Disulfide bonds were predicted between Cys34 of albumin and Cys311 of IgA, resulting in an oxidized form of albumin. Furthermore, complex formation prolongs the half-life of IgA molecules in the IgA-albumin complex, leading to excessive glycation of IgA molecules and affects the accumulation of IgA in serum. These findings may demonstrate why complications such as hyperviscosity syndrome occur more often in patients with IgA dimer producing multiple myeloma.

Optical coherence tomography for evaluating capillary waves in blood and plasma

Capillary waves are associated with fluid mechanical properties. Optical coherence tomography (OCT) has previously been used to determine the viscoelasticity of soft tissues or cornea. Here we report that OCT was able to evaluate phase velocities of capillary waves in fluids. The capillary waves of water, porcine whole blood and plasma on the interfacial surface, air-fluid in this case, are discussed in theory, and phase velocities of capillary waves were estimated by both our OCT experiments and theoretical calculations. Our experiments revealed highly comparable results with theoretical calculations. We concluded that OCT would be a promising tool to evaluate phase velocities of capillary waves in fluids. The methods described in this study could be applied to determine surface tensions and viscosities of fluids for differentiating hematological diseases in the future potential biological applications.

Predictors of symptomatic hyperviscosity in Waldenström macroglobulinemia

Symptomatic hyperviscosity is a well-established phenomenon in Waldenström macroglobulinemia (WM). Monoclonal IgM can variably impact intrinsic serum viscosity, leading to widely disparate symptomatic thresholds for development of hyperviscosity-related symptoms. Data regarding the predictors of symptomatic hyperviscosity and outcomes related to this complication remain scarce and a recent study proposed that IgM >6000 mg/dL be considered a new criterion for initiating therapy in otherwise asymptomatic (smoldering) WM to pre-empt hyperviscosity-related injury. Herein, we attempt to identify predictors of the development of symptomatic hyperviscosity and its impact in patients with WM. Of 997 WM patients evaluated from January, 1996 through June, 2017, symptomatic hyperviscosity was observed in 130 (13%) patients. Overall survival (OS) of these 130 patients was similar to that of patients without symptomatic hyperviscosity (median: 11.5 vs 11.6 years; P = 0.63). On multivariate-analysis, only viscosity >1.8 cp (risk ratio: 4.0, P = 0.02) assessed at the time of WM diagnosis was an independent predictor for the development of subsequent symptomatic hyperviscosity. Among patients with smoldering WM and IgM >6000 mg/dL at diagnosis (n = 13) who were managed expectantly, the median time-to-initial therapy was 6.9 years and only 15% developed hyperviscosity-related symptoms subsequently. In summary, the occurrence of symptomatic hyperviscosity does not impact OS. Serum viscosity at diagnosis of WM, and not IgM concentration, represents the single most important independent predictor for development of subsequent hyperviscosity-related symptoms. Patients with smoldering WM and high serum IgM can be safely observed in the absence of any indications per the Consensus recommendations to initiate WM-directed therapy.

Acute hyperviscosity: syndromes and management

Plasma hyperviscosity is a rare complication of both monoclonal and polyclonal disorders associated with elevation of immunoglobulins. Asymptomatic patients with an elevation in the serum viscosity do not require plasma exchange, and the majority will have other indications for therapeutic intervention. For patients with hemorrhagic or central nervous system manifestations, plasma exchange is the therapy of choice and is relatively safe. Viscosity measurements are not required to initiate therapy if the index of suspicion is high and the clinical presentation is typical. However, patients should have a sample sent for confirmation of the diagnosis. Whole-blood hyperviscosity is seen in patients with extreme elevation of the red cell and white cell count. Phlebotomy of patients with primary and secondary elevation of the red cell count is a well-established therapy.

Syndrome d’hyperviscosité : mise au point pour les réanimateurs

Le syndrome d’hyperviscosité (SH) est une entité clinique composée de signes variables non spécifiques et dont le diagnostic repose sur un faisceau d’arguments contextuels, anamnestiques et clinicobiologiques. En dehors de la mesure de la viscosité plasmatique, l’examen le plus spécifique pour confirmer le diagnostic semble être le fond d’œil. L’incidence du SH est inconnue, mais il s’agit d’une complication rare d’un grand nombre de pathologies. La physiopathologie est en rapport avec une augmentation de la viscosité plasmatique ou avec une augmentation du nombre d’éléments figurés du sang et/ou une altération de la capacité de ces cellules à circuler dans le lit capillaire. Le SH relève toujours d’un traitement de la pathologie sous-jacente et d’un traitement symptomatique visant à diminuer la viscosité sanguine. Dans les formes les plus sévères, il peut être nécessaire de recourir à un traitement par aphérèse thérapeutique en urgence. Le pronostic dépend principalement de la pathologie sous-jacente.

Therapeutic plasma exchange for hyperviscosity syndrome secondary to high rheumatoid factor

Hyperviscosity syndrome (HVS) is most commonly associated with Waldenstrom's macroglobulinemia, where it may be life-threatening. HVS may also occur in autoimmune diseases; data pertaining to efficacy of therapeutic plasma exchange (TPE) in HVS arising in non-malignant gammopathy are limited. We report a case of 71-year-old female with erosive rheumatoid arthritis with profoundly elevated rheumatoid factor (57,400 IU/ml; normal <35) who presented with findings consistent with HVS: profound weakness, headache, epistaxis and plasma viscosity (8.5 centipoise). She was successfully treated with pulsed high-dose steroids and TPE. Her symptoms of HVS have not recurred and the plasma viscosity has remained less than 3 centipoise. Given a slow onset of non-specific symptoms, HVS may be missed, incurring high risk of adverse effect. In symptomatic patients with high RF activity, a high index of suspicion for HVS is necessary to ensure timely identification and treatment with TPE, a safe and effective therapy.

Serum IgM level as predictor of symptomatic hyperviscosity in patients with Waldenström macroglobulinaemia

Symptomatic hyperviscosity is a common clinical manifestation in patients with Waldenström macroglobulinaemia (WM) and high serum IgM levels. Prompt intervention is required to prevent catastrophic events, such as retinal or central nervous system bleeding. Identifying patients at high risk of symptomatic hyperviscosity might support the decision to treat asymptomatic patients before irreversible damage occurs. We carried out a large retrospective study in 825 newly diagnosed WM patients, of who 113 (14%) developed symptomatic hyperviscosity. The median serum IgM level at the time of symptomatic hyperviscosity was 61·8 g/l (range 31-124 g/l). Forty-four patients (36%) had symptomatic hyperviscosity at the time of WM diagnosis. A serum IgM level >60 g/l at diagnosis was associated with a median time to symptomatic hyperviscosity of 3 months, whereas the median time for patients with serum IgM level of 50·01-60 g/l was approximately 3 years. Adjusting for other clinical factors, the odds of developing symptomatic hyperviscosity were 370-fold higher with serum IgM levels >60 g/l, and showed an association with CXCR4 mutational status. Symptomatic hyperviscosity did not impact overall survival (P = 0·12). The findings support the use of serum IgM level >60 g/l as a criterion for initiation of therapy in an otherwise asymptomatic WM patient.

Relaxation-based viscosity mapping for magnetic particle imaging

Magnetic particle imaging (MPI) has been shown to provide remarkable contrast for imaging applications such as angiography, stem cell tracking, and cancer imaging. Recently, there is growing interest in the functional imaging capabilities of MPI, where 'color MPI' techniques have explored separating different nanoparticles, which could potentially be used to distinguish nanoparticles in different states or environments. Viscosity mapping is a promising functional imaging application for MPI, as increased viscosity levels in vivo have been associated with numerous diseases such as hypertension, atherosclerosis, and cancer. In this work, we propose a viscosity mapping technique for MPI through the estimation of the relaxation time constant of the nanoparticles. Importantly, the proposed time constant estimation scheme does not require any prior information regarding the nanoparticles. We validate this method with extensive experiments in an in-house magnetic particle spectroscopy (MPS) setup at four different frequencies (between 250 Hz and 10.8 kHz) and at three different field strengths (between 5 mT and 15 mT) for viscosities ranging between 0.89 mPa · s-15.33 mPa · s. Our results demonstrate the viscosity mapping ability of MPI in the biologically relevant viscosity range.

[Hyperviscosity syndrome]

Hyperviscosity syndrome is a life-threatening complication. Clinical manifestations include neurological impairment, visual disturbance and bleeding. Measurement of plasma or serum viscosity by a viscometer assesses the diagnosis. Funduscopic examination is a key exam because abnormalities are well-correlated with abnormal plasma viscosity. Etiologies are various but symptomatic hyperviscosity is more common in Waldenström's macroglobulinemia and multiple myeloma. Prompt treatment is needed: treatment of the underlying disease should be considered, but generally not sufficient. Symptomatic measures aim to not exacerbate blood viscosity while urgent plasmapheresis effectively reduces the paraprotein concentration and relieves symptoms.

Central retinal vein occlusion caused by hyperviscosity syndrome in a young patient with Sjögren's syndrome and MALT lymphoma

We report in this article central retinal vein occlusion (CRVO) caused by hyperviscosity syndrome (HVS) in a young patient with mucosa-associated lymphoid tissue (MALT) lymphoma and Sjögren's syndrome (SjS). A 32-year-old female was referred to our hospital from a local ophthalmologist. Fundoscopic examination and fluorescein angiogram revealed she had a serous retinal detachment in the right eye, together with CRVO (nonischemic type) in both eyes. Systemic examinations revealed hyperglobulinemia, increased blood viscosity, increased antinuclear antibody, increased rheumatoid arthritis particle aggregation, and increased anti-SS-A antibody. Together with a decreased salivary gland secretory function, she was eventually diagnosed as suffering from SjS. Moreover, a large cystic mass was found in the anterior mediastinum on the chest X-ray. Fine needle biopsy soon revealed she had MALT lymphoma. After eight courses of the administration of rituximab, cyclophosphamide, vincristine, and prednisolone (R-CVP), most laboratory values were normalized, including blood viscosity. Cystic mass in the anterior mediastinum decreased, and the conditions of CRVO in both eyes had much improved. Decreased best-corrected visual acuity (BCVA) in the right eye was fully restored by sixth month. Not only MALT lymphoma, but also SjS can cause secondary hyperglobulinemia. Indeed, immunoelectrophoresis-serum test showed a polyclonal pattern of hyperglobulinemia. Therefore, SjS was thought to be the primary reason of hyperglobulinemia in this patient, which induced HVS, eventually causing CRVO. R-CVP therapy was effective for not only MALT lymphoma but also SjS accompanied with HVS. Consequently, R-CVP therapy led to the improvement of CRVO.

A stepwise approach for the management of poisoning with extracorporeal treatments

The use of an extracorporeal treatment (ECTR) in a poisoned patient may be life-saving in a limited number of scenarios. The decision-processes surrounding the use of ECTR in poisoning is complex: most nephrologists are not trained to assess a poisoned patient while clinical toxicologists rarely prescribe ECTRs. Deciding on which ECTR is most appropriate for a poison requires a good understanding of the poison's physicochemical and pharmacokinetic properties. Further, a detailed understanding of the capabilities and limitations of the different ECTRs can be useful to select the most appropriate ECTR for a given clinical situation. This manuscript provides a stepwise approach to assess the usefulness of ECTRs in poisoning.

Available extracorporeal treatments for poisoning: overview and limitations

Poisoning is a significant public health problem. In severe cases, extracorporeal treatments (ECTRs) may be required to prevent or reverse major toxicity. Available ECTRs include intermittent hemodialysis, sustained low-efficiency dialysis, intermittent hemofiltration and hemodiafiltration, continuous renal replacement therapy, hemoperfusion, therapeutic plasma exchange, exchange transfusion, peritoneal dialysis, albumin dialysis, cerebrospinal fluid exchange, and extracorporeal life support. The aim of this article was to provide an overview of the technical aspects, as well as the potential indications and limitations of the different ECTRs used for poisoned patients.

Impact of biofluid viscosity on size and sedimentation efficiency of the isolated microvesicles

Microvesicles are nano-sized lipid vesicles released by all cells in vivo and in vitro. They are released physiologically under normal conditions but their rate of release is higher under pathological conditions such as tumors. Once released they end up in the systemic circulation and have been found and characterized in all biofluids such as plasma, serum, cerebrospinal fluid, breast milk, ascites, and urine. Microvesicles represent the status of the donor cell they are released from and they are currently under intense investigation as a potential source for disease biomarkers. Currently, the “gold standard” for isolating microvesicles is ultracentrifugation, although alternative techniques such as affinity purification have been explored. Viscosity is the resistance of a fluid to a deforming force by either shear or tensile stress. The different chemical and molecular compositions of biofluids have an effect on its viscosity and this could affect movements of the particles inside the fluid. In this manuscript we addressed the issue of whether viscosity has an effect on sedimentation efficiency of microvesicles using ultracentrifugation. We used different biofluids and spiked them with polystyrene beads and assessed their recovery using the Nanoparticle Tracking Analysis. We demonstrate that MVs recovery inversely correlates with viscosity and as a result, sample dilutions should be considered prior to ultracentrifugation when processing any biofluids.

Guidelines on the use of therapeutic apheresis in clinical practice--evidence-based approach from the Apheresis Applications Committee of the American Society for Apheresis

The American Society for Apheresis (ASFA) Apheresis Applications Committee is charged with a review and categorization of indications for therapeutic apheresis. Beginning with the 2007 ASFA Special Issue (fourth edition), the subcommittee has incorporated systematic review and evidence-based approach in the grading and categorization of indications. This Fifth ASFA Special Issue has further improved the process of using evidence-based medicine in the recommendations by refining the category definitions and by adding a grade of recommendation based on widely accepted GRADE system. The concept of a fact sheet was introduced in the Fourth edition and is only slightly modified in this current edition. The fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis. The article consists of 59 fact sheets devoted to each disease entity currently categorized by the ASFA as category I through III. Category IV indications are also listed.

Guidelines on the use of therapeutic apheresis in clinical practice—Evidence-based approach from the apheresis applications committee of the American society for apheresis

The American Society for Apheresis (ASFA) Apheresis Applications Committee is charged with a review and categorization of indications for therapeutic apheresis. This elaborate process had been undertaken every 7 years resulting in three prior publications in 1986, 1993, and 2000 of "The ASFA Special Issues." This article is the integral part of the Fourth ASFA Special Issue. The Fourth ASFA Special Issue is significantly modified in comparison to the previous editions. A new concept of a fact sheet has been introduced. The fact sheet succinctly summarizes the evidence for the use of therapeutic apheresis. A detailed description of the fact sheet is provided. The article consists of 53 fact sheets devoted to each disease entity currently categorized by the ASFA. Categories I, II, and III are defined as previously in the Third Special Issue. However, a few new therapeutic apheresis modalities, not yet approved in the United States or are currently in clinical trials, have been assigned category P (pending) by the ASFA Clinical Categories Subcommittee. The diseases assigned to category IV are discussed in a separate article in this issue.

Cerebral infarction in IgG multiple myeloma with hyperviscosity

Cerebral infarction is an uncommon complication in multiple myeloma with hyperviscosity. Serum hyperviscosity may cause a variety of clinical manifestations including bleeding from mucosal membranes, congestive heart failure, retinopathy, and various neurologic deficits. These manifestations have been attributed to the presence of large quantities of asymmetrical molecules of high molecular weight in the serum. We recently experienced a case of multiple myeloma with acute cerebral infarction, which caused by hyperviscosity, as an initial manifestation in IgG multiple myeloma, and reviewed the relevant literature of myeloma presenting with the stroke. A 68-yr-old woman abruptly developed hypesthesia and monoplegia in the left leg. The stroke confirmed by the brain MRI and MR angiography, which revealed acute infarction at the right anterior cerebral artery territory. On admission, routine blood tests showed a slight decrease in hemoglobin and a marked increase in erythrocyte sedimentation rate. Peripheral blood smear, serum protein electrophoresis, serum visocity, and bone marrow aspiration showed that she had IgG multiple myeloma with hyperviscosity. She was treated by chemotherapy with cyclophosphamide and discharged with the improved clinical condition.

Serum hyperviscosity syndrome responding to therapeutic plasmapheresis in a patient with primary Sjögren's syndrome

Hyperviscosity syndrome is a disorder first described in patients with Waldenström's macroglobulinemia and is not commonly seen in rheumatic diseases. Its association with Sjögren's syndrome is very rare and it has been reported in very few patients. We report the case of a patient with primary Sjögren's syndrome presenting as hyperviscosity syndrome who was successfully treated with therapeutic plasma exchange.

Hematocrit, volume expander, temperature, and shear rate effects on blood viscosity

Our goal was to determine and predict the effects of temperature, shear rate, hematocrit, and different volume expanders on blood viscosity in conditions mimicking deep hypothermia for cardiac operations. Blood was obtained from six healthy adults. Dilutions were prepared to hematocrits of 35%, 30%, 22.5%, and 15% using plasma, 0.9% NaCl, 5% human albumin, and 6% hydroxyethyl starch. Viscosity was measured over a range of shear rates (4.5-450 s(-1)) and temperature (0 degrees -37 degrees C). A parametric expression for predicting blood viscosity based on the study variables was developed, and its agreement with measured values tested. Viscosity was higher at low shear rates and low temperatures, especially at temperatures less than 15 degrees C (P: < 0.016 for all conditions in comparison with 37 degrees C). Decreasing hematocrit, especially to less than 22.5%, decreased viscosity. Hemodilution with albumin or 0.9% NaCl decreased blood viscosity more than hemodilution with plasma or 6% hydroxyethyl starch (P: < 0.01 for all cases). The derived mathematical model for viscosity as a function of temperature, hematocrit, shear rate, and diluent predicted viscosity values that correlated well with the measured values in experimental samples (r(2) > 0.92, P: < 0.001).

IMPLICATIONS

A theoretical model for blood viscosity predicted independent effects of temperature, shear rate, and hemodilution on viscosity over a wide range of physiologic conditions, including thermal extremes of deep hypothermia in an experimental setting. Moderate hemodilution to a hematocrit of 22% decreased blood viscosity by 30%-50% at a blood temperature of 15 degrees C, suggesting the potential to improve microcirculatory perfusion during deep hypothermia.

Central retinal vein occlusion due to hyperviscosity syndrome

A 57-year-old man with no previous medical history entered the emergency department with 2 days of painless vision loss in the left eye. The patient was diagnosed with central retinal vein occlusion (CRVO) and admitted for treatment. Further work-up revealed that the cause of his CRVO was a hyperviscosity syndrome secondary to multiple myeloma. The patient received two rounds of plasmapheresis with slight recovery of vision and was discharged 28 days later.

Rheumatoid hyperviscosity: analysis of a patient with intermediate complexes that block other autoantibodies and a review of the literature

OBJECTIVES

To report a patient who rheumatoid arthritis presented with hyperviscosity syndrome, analyze this patient's rheumatoid factor, and review the previously reported patients.

METHODS

Immunofluorescence for antinuclear antibodies, double immunodiffusion, enzyme-linked immunosorbent assay, and size exclusion chromatography were used before and after plasmapheresis to study the patient's rheumatoid hyperviscosity, and polyclonal gammopathy and references in identified papers was used to identify previously reported patients.

RESULTS

Similar to several previous patients, this patient's sera contained both IgG and IgM rheumatoid factor and abundant intermediate complexes. Other autoantibodies, either from the patient or from other patients, were masked by rheumatoid factor or intermediate complexes from the reported patients sera. Rheumatic hyperviscosity is seen uncommonly, being reported in only 18 patients with rheumatoid arthritis and nine with other rheumatic illnesses.

CONCLUSIONS

There are two mechanisms by which rheumatoid factor can lead to hyperviscosity, both of which require large amounts of rheumatoid factor. Rheumatoid hyperviscosity must be recognized because this life-threatening syndrome usually can be successfully treated with plasmapheresis acutely and immunosuppressives for long-term control.

Indications for emergency apheresis procedures

Therapeutic apheresis has gained tremendous popularity worldwide in the last 2 decades. Emergency procedures can be life saving but should be undertaken for limited indications. Our emergency indications and experiences since the 1970s are critically described.

Hyperviscosity syndrome

Hyperviscosity syndrome is clinically manifested by oronasal bleeding, retinal hemorrhages, and variable neurological symptoms. It occurs when resistance to flow of blood increases sharply, resulting in impaired transit through the microcirculatory system. The most common cause of hyperviscosity is increased concentrations of gamma globulins, either monoclonal in malignant disease or polyclonal, usually seen with rheumatic disorders. Increased numbers of red blood cells, as in polycythemia vera, can result in viscous blood. Extreme increases in concentrations of mature and immature white blood cells can also produce hyperviscosity. Treatment with plasma exchange is required when the clinical syndrome is symptomatic. Although plasma exchange is not a completely benign procedure, it represents the most effective method of controlling hyperviscosity.