Typical and Atypical Hemolytic Uremic Syndrome in the Critically Ill

Pregnancy-associated atypical hemolytic uremic syndrome. Case report

Pregnancy-associated atypical hemolytic uremic syndrome (P-aHUS) is a rare disease. There are only few reports in the literature, and most are in the puerperium period. It is a thrombotic microangiopathy (TMA) characterized for microangiopathic hemolytic anemia, thrombocytopenia, and renal dysfunction. We report the case of a pregnant patient at 26.3 gestation weeks, who developed clinical features of TMA, neurological alterations, and septic shock; then after fetus and placental delivery, no clinical improvement was observed; a diagnostic protocol was performed due to suspicion of P-aHUS, showing improvement after the plasma exchange sessions and eculizumab. We present here a brief review of the case since it is an entity that needs to be suspected during pregnancy when TMA features and requires an immediate diagnosis to provide timely treatment.

Underlying Genetics of aHUS: Which Connection with Outcome and Treatment Discontinuation?

Atypical hemolytic uremic syndrome (aHUS) is a rare disease caused by a genetic dysregulation of the alternative complement pathway, characterized by thrombocytopenia, hemolytic anemia, and acute kidney injury, and included in the group of thrombotic microangiopathies. With the introduction of humanized monoclonal antibodies that inhibit C5 activation, the natural history of aHUS completely changed, with a better prognosis, a quick recovery of renal function, and a significant reduction of end-stage renal disease incidence. Nowadays, there is an increasing interest in the molecular and genetic bases of this severe disease. The aim of this narrative review is to provide readers with a practical guide about different possible involved genes, elucidating the specific role of each transcribed protein in the pathogenesis of aHUS. Moreover, we analyzed the main current evidence about the relationship among genetic mutations, outcomes, and the risk of recurrence of this manifold disease.

Thrombotic microangiopathies in critically ill children: The MATUCIP registry in Spain

INTRODUCTION

Thrombotic microangiopathies (TMA) are rare diseases usually presenting with renal, haematological, neurologic and cardiovascular involvement and nonspecific but severe symptoms. A registry of TMA cases managed in Spanish paediatric intensive care units (the MATUCIP Registry) was established with the aim of gaining knowledge on their clinical characteristics, diagnosis and acute-phase treatment.

METHODS

We conducted a prospective multicentre observational study in 20 paediatric intensive care units (PICUs) in Spain from January 2017 to December 2021 in children aged more than 1 month with TMAs, who were followed up through the discharge from the PICU.

RESULTS

The sample included 97 patients (51.5% female) with a median age of 2.6 years (interquartile range [IQR], 1.6-5.7). The initial manifestations were gastrointestinal (74.2%), respiratory (14.4%), fever (5.2%), neurologic (3.1%) and other (3.1%). At admission, 75.3% of patients had microangiopathic haemolytic anaemia, 95.9% thrombocytopenia and 94.8% acute kidney injury. Of the total sample, 57.7% of patients received a diagnosis of Shiga toxin-associated haemolytic uraemic syndrome (HUS), 14.4% of Streptococcus pneumoniae-associated HUS, 15.6% of atypical HUS, 10.3% of secondary TMA and 2.1% of thrombotic thrombocytopenic purpura. Eighty-seven patients (89.7%) developed arterial hypertension, and 49.5% gastrointestinal, 22.7% respiratory, 25.8% neurologic and 12.4% cardiac manifestations. Also, 60.8% required renal replacement therapy and 2.1% plasma exchange. Twenty patients received eculizumab. The median PICU stay was 8.5 days (IQR, 5-16.5). Two children died.

CONCLUSIONS

The MATUCIP registry demonstrates the clinical variability of TMA cases requiring admission to the PICU. Knowledge of the presentation and outcomes of TMAs can facilitate early aetiological diagnosis. This registry can help improve our understanding of the clinical spectrum of these diseases, for which there is a dearth of published data.

[Thrombotic microangiopathies in surgical intensive care medicine with special consideration of atypical hemolytic uremic syndrome]

Thrombotic microangiopathies (TMA) are rare diseases, which are defined by the triad microangiopathic hemolytic anemia, thrombocytopenia and organ damage, and are associated with high morbidity and mortality. The recognition of a TMA and the distinction of important differential diagnoses are key factors, particularly in a perioperative context and in routine clinical intensive care. The further differentiation of the different TMA subtypes, such as thrombotic thrombocytopenic purpura (TTP), Shiga toxin-producing Escherichia coli hemolytic uremic syndrome (STEC-HUS) and atypical hemolytic uremic syndrome (aHUS), based on the underlying pathophysiology and the development of new targeted treatment options in recent years have significantly improved the prognosis. A close interdisciplinary cooperation between critical care specialists and specialist disciplines experienced in the treatment of TMA, is essential for a prompt diagnosis and the initiation of the appropriate treatment.

Anemia in the pediatric patient

The World Health Organization estimates that approximately a quarter of the world's population suffers from anemia, including almost half of preschool-age children. Globally, iron deficiency anemia is the most common cause of anemia. Other important causes of anemia in children are hemoglobinopathies, infection, and other chronic diseases. Anemia is associated with increased morbidity, including neurologic complications, increased risk of low birth weight, infection, and heart failure, as well as increased mortality. When approaching a child with anemia, detailed historical information, particularly diet, environmental exposures, and family history, often yield important clues to the diagnosis. Dysmorphic features on physical examination may indicate syndromic causes of anemia. Diagnostic testing involves a stepwise approach utilizing various laboratory techniques. The increasing availability of genetic testing is providing new mechanistic insights into inherited anemias and allowing diagnosis in many previously undiagnosed cases. Population-based approaches are being taken to address nutritional anemias. Novel pharmacologic agents and advances in gene therapy-based therapeutics have the potential to ameliorate anemia-associated disease and provide treatment strategies even in the most difficult and complex cases.

Hemophagocytic Lymphohistiocytosis Associated With Hemolytic Uremic Syndrome in a Child: A Case Report and Systematic Literature Review

Hemophagocytic lymphohistiocytosis (HLH) is a life-threatening disorder resulting from excessive activation and nonmalignant proliferation of T-lymphocytes and macrophages. Hemolytic uremic syndrome (HUS) is a disease characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Reports pertaining to the association between HLH and HUS are rarely published; however, we report on a 4-year-old boy who was diagnosed with both conditions and treated successfully with high-dose steroid and intravenous immunoglobulin. Differentiating HUS from HLH can be challenging because of their clinical similarities. Therefore, prompt diagnosis and immunosuppressive treatment are essential and life-saving to these patients.

Complement Levels at Admission Reflecting Progression to Severe Acute Kidney Injury (AKI) in Coronavirus Disease 2019 (COVID-19): A Multicenter Prospective Cohort Study

Background

Dysregulation of complement system is thought to be a major player in development of multi-organ damage and adverse outcomes in patients with coronavirus disease 2019 (COVID-19). This study aimed to examine associations between complement system activity and development of severe acute kidney injury (AKI) among hospitalized COVID-19 patients.

Materials and Methods

In this multicenter, international study, complement as well as inflammatory and thrombotic parameters were analyzed in COVID-19 patients requiring hospitalization at one US and two Hungarian centers. The primary endpoint was development of severe AKI defined by KDIGO stage 2+3 criteria, while the secondary endpoint was need for renal replacement therapy (RRT). Complement markers with significant associations with endpoints were then correlated with a panel of inflammatory and thrombotic biomarkers and assessed for independent association with outcome measures using logistic regression.

Results

A total of 131 hospitalized COVID-19 patients (median age 66 [IQR, 54–75] years; 54.2% males) were enrolled, 33 from the US, and 98 from Hungary. There was a greater prevalence of complement over-activation and consumption in those who developed severe AKI and need for RRT during hospitalization. C3a/C3 ratio was increased in groups developing severe AKI (3.29 vs. 1.71; p < 0.001) and requiring RRT (3.42 vs. 1.79; p < 0.001) in each cohort. Decrease in alternative and classical pathway activity, and consumption of C4 below reference range, as well as elevation of complement activation marker C3a above the normal was more common in patients progressing to severe AKI. In the Hungarian cohort, each standard deviation increase in C3a (SD = 210.1) was independently associated with 89.7% increased odds of developing severe AKI (95% CI, 7.6–234.5%). Complement was extensively correlated with an array of inflammatory biomarkers and a prothrombotic state.

Conclusion

Consumption and dysregulation of complement system is associated with development of severe AKI in COVID-19 patients and could represent a promising therapeutic target for reducing thrombotic microangiopathy in SARS-CoV-2 infection.

Treatment of Shiga-Toxin Hus with Severe Neurologic Features with Eculizumab

Hemolytic Uremic Syndrome (HUS) is a constellation of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal failure. Shiga toxin-producing Escherichia coli- (STEC-) mediated HUS is a common cause of acute renal failure in children and can rarely result in severe neurological complications such as encephalopathy, seizures, cerebrovascular accidents, and coma. Current literature supports use of eculizumab, a monoclonal antibody that blocks complement activation, in atypical HUS (aHUS). However, those with neurologic complications from STEC-HUS have complement activation and deposition of aggregates in microvasculature and may be treated with eculizumab. In this case report, we describe a 3-year-old boy with diarrhea-positive STEC-HUS who developed severe neurologic involvement in addition to acute renal failure requiring renal replacement therapy. He was initiated on eculizumab therapy, with clinical improvement and organ recovery. This case highlights systemic complications of STEC-HUS in a pediatric patient. The current literature is limited but has suggested a role for complement mediation in cases with severe complications. We review the importance of early recognition of complications, use of eculizumab, and current data available.

A case of hemolytic uremic syndrome caused by Shiga toxin-producing Escherichia coli after pericardiectomy

The majority of cases of Shiga toxin-producing Escherichia coli are self-limited; however, the infection can occasionally be complicated by more severe phenomena, such as thrombotic microangiopathy, with resultant end-organ damage to the kidneys, colon, nervous system, and various other tissues. Shiga toxin-induced hemolytic uremic syndrome (ST-HUS)-the constellation of thrombocytopenia, hemolysis, and renal failure resulting from thrombotic microangiopathy in a subset of infections producing the Shiga toxin-is classically observed in the pediatric population. Nevertheless, the diagnosis should be considered in adults with this presentation, and especially in those with colonic findings suggestive of ischemia. ST-HUS must also be distinguished from other thrombotic microangiopathies and related conditions, such as disseminated intravascular coagulation, thrombotic thrombocytopenic purpura, and complement-mediated HUS, as these diagnoses prompt alternate management strategies. Here, we present a case of ST-HUS in a gentleman following pericardiectomy who was infected with non-O157:H7 E. coli producing Shiga toxin 2.

Therapeutic plasma exchange in critically ill children: experience of the pediatric intensive care unit of two centers in Chile

INTRODUCTION

Therapeutic plasma exchange (TPE) is an extracorporeal blood purification technique used in a wide spectrum of diseases. We aim to review the indications, complications, and outcomes of critically ill children who received TPE and to compare a membrane versus centrifugal method in this cohort.

METHODS

A retrospective observational study in two pediatric intensive care units in Chile during eight years (2011-2019) Results: A total of 36 patients underwent 167 TPE sessions (20 centrifugation and 16 membrane-based). The more frequent indications for TPE were autoimmune neurological diseases in 14 cases, renal diseases (9), and rheumatological disorders (5). 58 % of children received other immunomodulatory therapy. According to ASFA, 45 % of cases were I-II category, 50 % to III, and 5% not classified. Response to treatment was complete in 64 % (23/36) and partial in 33 % (12/36). Complications occurred in 17.4 % of sessions, and the most frequent was transient hypotension during the procedure. Overall survival at discharge from the PICU was 92 %. Patients who received TPE as a single therapy (n = 26) survived 96 %. The clinical outcomes between the two apheresis methods were similar. Survivors had a significantly lower PELOD score on admission (14.5 vs. 6.5, p = 0.004).

CONCLUSIONS

TPE is mainly indicated as a rescue treatment in neurological autoimmune diseases refractory to conventional immunomodulatory treatment. Complications in critically ill children are mild and low. The outcome in children requiring TPE as a single therapy is good, and no differences were observed with centrifugation or membrane method.

Complement levels at admission as a reflection of coronavirus disease 2019 (COVID-19) severity state

Complement system hyperactivation has been proposed as a potential driver of adverse outcomes in severe acute respiratory syndrome coronavirus 2 infected patients, given prior research of complement deposits found in tissue and blood samples, as well as evidence of clinical improvement with anticomplement therapy. Its role in augmenting thrombotic microangiopathy mediated organ damage has also been implicated in coronavirus disease 2019 (COVID‐19). This study aimed to examine associations between complement parameters and progression to severe COVID‐19 illness, as well as correlations with other systems. Blood samples of COVID‐19 patients presenting to the emergency department (ED) were analyzed for a wide panel of complement and inflammatory biomarkers. The primary outcome was COVID‐19 severity at index ED visit, while the secondary outcome was peak disease severity over the course of illness. Fifty‐two COVID‐19 patients were enrolled. C3a (p = 0.018), C3a/C3 ratio (p = 0.002), and sC5b‐9/C3 ratio (p = 0.021) were significantly elevated in with severe disease at ED presentation. Over the course of illness, C3a (p = 0.028) and C3a/C3 ratio (p = 0.003) were highest in the moderate severity group. In multivariate regression controlled for confounders, complement hyperactivation failed to predict progression to severe disease. C3a, C3a/C3 ratio, and sC5b‐9/C3 ratio were correlated positively with numerous inflammatory biomarkers, fibrinogen, and VWF:Ag, and negatively with plasminogen and ADAMTS13 activity. We found evidence of complement hyperactivation in COVID‐19, associated with hyperinflammation and thrombotic microangiopathy. Complement inhibition should be further investigated for potential benefit in patients displaying a hyperinflammatory and microangiopathic phenotype.

Hemolytic uremic syndrome caused by sea anemone sting: a case report

Background

Some sea anemone toxins cause renal injuries resembling hemolytic uremic syndrome (HUS). To date, only a few cases of HUS caused by sea anemone stings have been reported. In this case report, we have described an HUS case caused by a sea anemone sting.

Case presentation

In November 2019, a 37-year-old man with no underlying disease was admitted to our hospital. He presented with intense pain, a rash on, and swelling in his right thigh. Two days prior, he had been stung by a sea anemone while scuba diving in Cebu, Philippines. His blood tests revealed renal dysfunction, and his platelet count was normal. However, on day three, the platelet count decreased rapidly. His blood haptoglobin level decreased, and schistocytes were identified on the peripheral blood smear. We suspected thrombotic microangiopathy and started the conventional treatment, comprising hemodialysis, blood transfusion, and antibiotic administration. ADAMTS-13 and genetic test results associated with atypical HUS were normal. Therefore, the patient was diagnosed with HUS caused by a sea anemone toxin.

Conclusions

HUS caused by a sea anemone toxin is rare, but it is a serious medical disease. Clinicians should consider HUS in patients with such clinical presentations, and they should make prompt treatment-related decisions.

Postoperative Atypical Hemolytic Uremic Syndrome in a 67-Year-Old Woman Associated with Hemolytic Anemia, Thrombocytopenia, and Acute Renal Failure

Patient: Female, 67-year-old

Final Diagnosis: Atypical hemolytic uremic syndrome

Symptoms: Anemia • renal failure • thrombocytopenia

Medication: —

Clinical Procedure: —

Specialty: Hematology • General and Internal Medicine • Pathology

COVID-19: Are we dealing with a multisystem vasculopathy in disguise of a viral infection?

After the emergence of Severe Acute Respiratory Syndrome Coronavirus (SARS-CoV) and Middle East Respiratory Syndrome Coronavirus (MERS-CoV) in the last two decades, the world is facing its new challenge in Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) pandemic with unprecedented global response. With the expanding domain of presentations in COVID-19 patients, the full range of manifestations is yet to unfold. The classical clinical symptoms for SARS-CoV-2 affected patients are dry cough, high fever, dyspnoea, lethal pneumonia whereas many patients have also been found to be associated with a few additional signs and clinical manifestations of isolated vasculopathy. Albeit a deep and profound knowledge has been gained on the clinical features and management of COVID-19, less clear association has been provided on SARS-CoV-2 mediated direct or indirect vasculopathy and its possible correlation with disease prognosis. The accumulative evidences suggest that novel coronavirus, apart from its primary respiratory confinement, may also invade vascular endothelial cells of several systems including cerebral, cardio-pulmonary as well as renal microvasculature, modulating multiple visceral perfusion indices. Here we analyse the phylogenetic perspective of SARS-CoV-2 along with other strains of β-coronaviridae from a standpoint of vasculopathic derangements. Based on the existing case reports, literature and open data bases, we also analyse the differential pattern of vasculopathy related changes in COVID-19 positive patients. Besides, we debate the need of modulation in clinical approach from a hemodynamical point of view, as a measure towards reducing disease transmission, morbidity and mortality in SARS-CoV-2 affected patients.

Complement associated microvascular injury and thrombosis in the pathogenesis of severe COVID-19 infection: A report of five cases

Acute respiratory failure and a systemic coagulopathy are critical aspects of the morbidity and mortality characterizing infection with severe acute respiratory distress syndrome-associated coronavirus-2, the etiologic agent of Coronavirus disease 2019 (COVID-19). We examined skin and lung tissues from 5 patients with severe COVID-19 characterized by respiratory failure (n= 5) and purpuric skin rash (n = 3). COVID-19 pneumonitis was predominantly a pauci-inflammatory septal capillary injury with significant septal capillary mural and luminal fibrin deposition and permeation of the interalveolar septa by neutrophils. No viral cytopathic changes were observed and the diffuse alveolar damage (DAD) with hyaline membranes, inflammation, and type II pneumocyte hyperplasia, hallmarks of classic acute respiratory distress syndrome, were not prominent. These pulmonary findings were accompanied by significant deposits of terminal complement components C5b-9 (membrane attack complex), C4d, and mannose binding lectin (MBL)-associated serine protease (MASP)2, in the microvasculature, consistent with sustained, systemic activation of the complement pathways. The purpuric skin lesions similarly showed a pauci-inflammatory thrombogenic vasculopathy, with deposition of C5b-9 and C4d in both grossly involved and normally-appearing skin. In addition, there was co-localization of COVID-19 spike glycoproteins with C4d and C5b-9 in the interalveolar septa and the cutaneous microvasculature of 2 cases examined. In conclusion, at least a subset of sustained, severe COVID-19 may define a type of catastrophic microvascular injury syndrome mediated by activation of complement pathways and an associated procoagulant state. It provides a foundation for further exploration of the pathophysiologic importance of complement in COVID-19, and could suggest targets for specific intervention.

Complement associated microvascular injury and thrombosis in the pathogenesis of severe COVID-19 infection: A report of five cases

Acute respiratory failure and a systemic coagulopathy are critical aspects of the morbidity and mortality characterizing infection with severe acute respiratory distress syndrome-associated coronavirus-2, the etiologic agent of Coronavirus disease 2019 (COVID-19). We examined skin and lung tissues from 5 patients with severe COVID-19 characterized by respiratory failure (n= 5) and purpuric skin rash (n = 3). COVID-19 pneumonitis was predominantly a pauci-inflammatory septal capillary injury with significant septal capillary mural and luminal fibrin deposition and permeation of the interalveolar septa by neutrophils. No viral cytopathic changes were observed and the diffuse alveolar damage (DAD) with hyaline membranes, inflammation, and type II pneumocyte hyperplasia, hallmarks of classic acute respiratory distress syndrome, were not prominent. These pulmonary findings were accompanied by significant deposits of terminal complement components C5b-9 (membrane attack complex), C4d, and mannose binding lectin (MBL)-associated serine protease (MASP)2, in the microvasculature, consistent with sustained, systemic activation of the complement pathways. The purpuric skin lesions similarly showed a pauci-inflammatory thrombogenic vasculopathy, with deposition of C5b-9 and C4d in both grossly involved and normally-appearing skin. In addition, there was co-localization of COVID-19 spike glycoproteins with C4d and C5b-9 in the interalveolar septa and the cutaneous microvasculature of 2 cases examined. In conclusion, at least a subset of sustained, severe COVID-19 may define a type of catastrophic microvascular injury syndrome mediated by activation of complement pathways and an associated procoagulant state. It provides a foundation for further exploration of the pathophysiologic importance of complement in COVID-19, and could suggest targets for specific intervention.