Weibel-Palade bodies: function and role in thrombotic thrombocytopenic purpura and in diarrhea phase of STEC-hemolytic uremic syndrome.

Vascular endothelial cells are equipped with numerous specialized granules called Weibel-Palade bodies (WPBs). They contain a cocktail of proteins that can be rapidly secreted (3-5 min) into the vascular lumen after an appropriate stimulus such as thrombin. These proteins are ready without synthesis. Von Willebrand factor (VWF) and P-selectin are the main constituents of WPBs. Upon stimulation, release of ultralarge VWF multimers occurs and assembles into VWF strings on the apical side of endothelium. The VWF A1 domain becomes exposed in a shear-dependent manner recruiting and activating platelets. VWF is able to recruit leukocytes via direct leukocyte binding or via the activated platelets promoting NETosis. Ultralarge VWF strings are ultimately cleaved into smaller pieces by the protease ADAMTS-13 preventing excessive platelet adhesion. Under carefully performed flowing conditions and adequate dose of Shiga toxins, the toxin induces the release of ultralarge VWF multimers from cultured endothelial cells. This basic information allows insight into the pathogenesis of thrombotic thrombocytopenic purpura (TTP) and of STEC-HUS in the diarrhea phase. In TTP, ADAMTS-13 activity is deficient and systemic aggregation of platelets will occur after a second trigger. In STEC-HUS, stimulated release of WPB components in the diarrhea phase of the disease can be presumed to be the first hit in the damage of Gb3 positive endothelial cells.

A Severe Form of Atypical Hemolytic Uremic Syndrome in a Two-Year-Old Girl: A Case Report.

Hemolytic uremic syndrome (HUS) is a prevalent cause of severe acute kidney injury in children, often leading to chronic renal damage. It is characterized by thrombotic microangiopathy (TMA), which represents a triad of microangiopathic hemolytic anemia, thrombocytopenia, and renal impairment. The choice of treatment and management strategies depends primarily on the underlying etiology. We present the case of a two-year-old girl diagnosed with rapidly progressive glomerulonephritis accompanied by hypertension necessitating renal replacement therapy. Initial laboratory findings indicated positive antinuclear antibodies, prompting immunosuppression and renal biopsy, revealing TMA with minimal chronicity changes. The treatment involved plasmapheresis and a single dose of injection rituximab, resulting in clinical recovery with an improved glomerular filtration rate. Since the anti-complement factor H antibody result was negative, the genetic etiology of atypical HUS was considered. The patient was discharged with favorable outcomes, including normal urine output and the absence of edema. This case concludes that young children with atypical HUS may present with a severe clinical course necessitating early intervention. The lack of genetic analysis facilities in severe cases should not hinder the timely initiation of plasmapheresis to prevent further injury and progression to chronic kidney disease.

Eculizumab for Shiga-toxin-induced hemolytic uremic syndrome in adults with neurological involvement.

The role of eculizumab in treating Shiga-toxin-producing Escherichia coli (STEC) hemolytic uremic syndrome (HUS) patients with neurological involvement remains unclear. We describe two distinctly different STEC-HUS patients with neurologic involvement successfully managed with eculizumab, and perform a literature review of all published cases. Both patients had complete resolution of neurological symptoms after initiation of eculizumab. Eighty patients with STEC-HUS treated with eculizumab were identified in the literature, 68.7% had complete resolution of neurological symptoms. Based on our experience and literature review, three prevailing themes were noted: 1) Early eculizumab administration optimized neurological outcomes, 2) Symptom resolution may not be immediate, neurological symptoms may initially worsen before improvement, and 3) Plasma exchange yielded no benefit. Early administration of eculizumab may reverse neurotoxicity in patients with STEC-HUS.

Veno-venous extracorporeal membrane oxygenation in managing acute respiratory distress syndrome associated with hemolytic uremic syndrome and septic shock: a case report.

Veno-venous extracorporeal membrane oxygenation (VV-ECMO) is a rescue therapy for severe respiratory failure in which conventional mechanical ventilation therapy is unsuccessful. Hemolysis during VV-ECMO support arises from multiple factors associated with organ damage and poor outcomes. Therefore, close and prompt monitoring is needed. Hemolytic uremic syndrome (HUS) is characterized by hemolysis, acute renal failure, and thrombocytopenia. Hemolytic features of the disease may complicate VV-ECMO management. A 26-year-old man with a history of cerebral palsy underwent VV-ECMO for acute respiratory distress syndrome (ARDS) due to septic shock caused by bacterial translocation during treatment for HUS. He showed features of hemolysis, with elevated lactate dehydrogenase (LDH), fragmented red blood cells, and low haptoglobin levels. Plasma free hemoglobin was measured daily throughout the whole course of ECMO with levels higher than 10 mg/dL but not exceeding 50 mg/dL. The extracorporeal membrane oxygenation (ECMO) circuit pressures were carefully monitored to ensure the pump generated no excessive negative pressure. The patient was weaned off ECMO on the eleventh day. There have been several cases of VA-ECMO in patients with HUS; however, there is limited literature on VV-ECMO. As the days on VV-ECMO tend to be longer than those on VA-ECMO, features of hemolysis may complicate management. Although HUS did not directly influence the clinical course in the present case, features of hemolysis were continuously observed. This case highlighted the importance of standard ECMO monitoring, especially daily measurement of plasma free hemoglobin.

Anti-factor H Autoantibody-Associated Hemolytic Uremic Syndrome: A Rare Entity in a Pediatric Patient.

An 11-year-old patient presented with the primary complaint of hematuria and vomiting. On further investigation and a series of diagnostic tests, including a biopsy and thrombotic microangiopathy (TMA) profile, the patient was diagnosed with thrombotic microangiopathy. TMA is a pathological process involving endothelial cell injury, leading to thrombocytopenia and microangiopathic hemolytic anemia. This case highlights the importance of considering TMA in pediatric patients presenting with nonspecific symptoms, such as loss of appetite. Further research is needed to understand the pathophysiology and optimal management strategies for pediatric TMA. This case adds to the growing body of literature on pediatric TMA and underscores the need for a high index of suspicion in similar clinical scenarios.

Isolated cerebellar stroke in a paediatric patient with typical haemolytic uraemic syndrome: a case report and literature review.

Haemolytic Uraemic Syndrome (HUS) is a rare medical condition characterised by microangiopathic haemolytic anaemia, thrombocytopenia, and acute kidney injury. Neurological complications are documented but rarely involve the cerebellum. We present a unique case of a 23-month-old male with HUS triggered by Escherichia coli-O157 (E.coli-O157) infection leading to an isolated cerebellar stroke.The patient initially presented with fever, bloody stools, and seizures. Confirmation of E.coli-O157 infection was obtained, and MRI revealed an isolated cerebellar stroke. Treatment included supportive care, anticoagulation for a right atrial thrombus, with gradual improvement observed.This case highlights the unusual occurrence of isolated cerebellar stroke in HUS patients, emphasising the importance of promptly recognizing manifestations of the central nervous system and the necessity for a multidisciplinary approach. Finally, a comprehensive literature review was conducted to identify cases of HUS patients with cerebellar involvement.

Novel mechanisms of action of emerging therapies of hereditary thrombotic thrombocytopenic purpura.

INTRODUCTION: Hereditary thrombotic thrombocytopenic purpura (hTTP) is caused by deficiency of plasma ADAMTS13 activity, resulting from ADAMTS13 mutations. ADAMTS13 cleaves ultra large von Willebrand factor (VWF), thus reducing its multimer sizes. Hereditary deficiency of plasma ADAMTS13 activity leads to the formation of excessive platelet-VWF aggregates in small arterioles and capillaries, resulting in hTTP. AREAS COVERED: PubMed search from 1956 to 2024 using thrombotic thrombocytopenic purpura and therapy identified 3,675 articles. Only the articles relevant to the topic were selected for discussion, which focuses on pathophysiology, clinical presentations, and mechanisms of action of emerging therapeutics for hTTP. Current therapies include infusion of plasma, or coagulation factor VIII, or recombinant ADAMTS13. Emerging therapies include anti-VWF A1 aptamers or nanobody and gene therapies with adeno-associated viral vector or self-inactivated lentiviral vector or a sleeping beauty transposon system for a long-term expression of a functional ADAMTS13 enzyme. EXPERT OPINION: Frequent plasma infusion remains to be the standard of care in most parts of the world, while recombinant ADAMTS13 has become the treatment of choice for hTTP in some of the Western countries. The success of gene therapies in preclinical models may hold a promise for future development of these novel approaches for a cure of hTTP.

Do asymptomatic STEC-long-term carriers need to be isolated or decolonized? New evidence from a community case study and concepts in favor of an individualized strategy.

Asymptomatic long-term carriers of Shigatoxin producing Escherichia coli (STEC) are regarded as potential source of STEC-transmission. The prevention of outbreaks via onward spread of STEC is a public health priority. Accordingly, health authorities are imposing far-reaching restrictions on asymptomatic STEC carriers in many countries. Various STEC strains may cause severe hemorrhagic colitis complicated by life-threatening hemolytic uremic syndrome (HUS), while many endemic strains have never been associated with HUS. Even though antibiotics are generally discouraged in acute diarrheal STEC infection, decolonization with short-course azithromycin appears effective and safe in long-term shedders of various pathogenic strains. However, most endemic STEC-strains have a low pathogenicity and would most likely neither warrant antibiotic decolonization therapy nor justify social exclusion policies. A risk-adapted individualized strategy might strongly attenuate the socio-economic burden and has recently been proposed by national health authorities in some European countries. This, however, mandates clarification of strain-specific pathogenicity, of the risk of human-to-human infection as well as scientific evidence of social restrictions. Moreover, placebo-controlled prospective interventions on efficacy and safety of, e.g., azithromycin for decolonization in asymptomatic long-term STEC-carriers are reasonable. In the present community case study, we report new observations in long-term shedding of various STEC strains and review the current evidence in favor of risk-adjusted concepts.

Successful Management of Atypical Hemolytic-Uremic Syndrome in Pregnancy Using Eculizumab: A Case Review.

Hemolytic-uremic syndrome (HUS) is a rare thrombotic microangiopathy characterized by the triad of microangiopathic hemolytic anemia (MAHA), thrombocytopenia, and acute kidney injury. The disease is pathologically marked by fibrinoid necrosis within renal arterioles and glomerular capillaries. HUS can be categorized into typical variants, often linked to Shiga toxin-producing Escherichia coli (STEC) infection, and atypical variants that stem from dysregulation in the alternative complement pathway. Pregnancy is a recognized predisposing condition for HUS due to the potential reduction in complement regulatory proteins and the possibility of heightened maternal immune response. This report illustrates the case of a 36-year-old woman who, at 36 weeks of gestation, faced a breech presentation and was diagnosed with atypical HUS (aHUS) after placental abruption. Following a cesarean section, she developed complications, including a pelvic hematoma and bilateral hydronephrosis. Despite initial suboptimal response to plasmapheresis, the patient exhibited marked clinical improvement with eculizumab treatment, with no evidence of disease relapse.

Dynamic evolution of kidney function in patients with STEC-hemolytic uremic syndrome followed for more than 15 years: unexpected changes.

BACKGROUND: Most studies regarding kidney outcomes in patients with Shiga toxin-producing Escherichia coli-hemolytic uremic syndrome (STEC-HUS) focus on kidney status at last assessment. We aimed to describe patterns of changes in kidney function during follow-up and investigate associations between kidney function at 1st, 5th, and 10th year after onset and long-term kidney outcomes. METHODS: Data of patients with STEC-HUS followed for at least 15 years were analyzed. Kidney function patterns were constructed considering kidney status at 1st, 5th, 10th, and ≥ 15 years and defined as (1) progressive, if patients changed from complete recovery to any chronic kidney disease (CKD) stage or if CKD worsened; (2) improvement, if they shifted from any CKD stage to complete recovery or to a milder stage; and (3) stable, if remained unchanged. RESULTS: Of 152 patients included, after 1 year of follow-up, 47% had complete recovery, 22% CKD1, and 32% CKD2-5. At last assessment, 46% had complete recovery, 34% CKD1, and 19% CKD2-5. Despite percentages seeming similar, patients differed: 48% were stable, 27% improved, and 25% worsened. Further, 62% of patients with CKD2-4 in the 1st year normalized their glomerular filtration rate (GFR) thereafter. Comparison of kidney function between 1st, 5th, and 10th year to last assessment shows a stable pattern in 48, 59, and 69% respectively. CONCLUSIONS: Changes in kidney function showed a dynamic and complex behavior, with patients moving from one group to another. Consistently, kidney function neither at the 1st, 5th, or 10th year was representative of final outcome. Unexpectedly, two-thirds of patients with CKD2-4 after 1 year achieved normal eGFR later during follow-up.

A formação acadêmica em educação física para a atenção básica do SUS: uma revisão integrativa em teses e dissertações / Academic training in physical education for primary care in the SUS: an integrative review of theses and dissertations / La formación académica en educación física para la atención primaria en el SUS: una revisión integradora de tesis y disertaciones

Faz-se necessário abordar criticamente a promoção da saúde e os elementos que impactam o processo saúde/doença no cotidiano da formação do professor de Educação Física (EF). Portanto, este estudo tem como objetivo analisar teses e dissertações produzidas sobre a formação acadêmica em EF e sua relação com a saúde no contexto do Sistema Único de Saúde (SUS), por meio de uma revisão integrativa. O estudo encontrou seis dissertações que mostraram que apesar da percepção das universidades de que a formação acadêmica permite aos professores de EF atuar no SUS, é possível identificar a manutenção do discurso conservador e biomédico, o que afeta a compreensão, a percepção e a ação dos professores de EF em equipes multiprofissionais no contexto da Saúde Coletiva presente no SUS (AU).

It is necessary to critically approach health promotion and the elements that impact the health/disease process in the daily training of Physical Education (PE) teachers. Therefore, this study aims to analyze the theses and dissertations produced on academic training in PE and its relationship with health in the context of the Unified Health System (SUS), through an integrative review. The study found six dissertations that showed that, despite the universities' perception that academic training allows PE teachers to work in the SUS, it is possible to identify the maintenance of the conservative and biomedical discourse, which affects understanding, perception and action of PE teachers in multidis-ciplinary teams in the context of Collective Health in the present SUS (AU)

Es necesario abordar críticamente la promoción de la salud y los elementos que impactan el proceso salud/enfermedad en la formación diaria de los docentes de Educación Física (EF). Por lo tanto, este estudio tiene como objetivo analizar tesis y disertaciones producidas sobre la formación académica en EF y su relación con la salud en el contexto del Sistema Único de Salud (SUS), a través de una revisión integradora. El estudio encontró seis disertaciones que demostraron que, a pesar de la percepción de las universidades de que la formación académica permite que los profesores de EF actúen en el SUS, es posible identificar el mantenimiento del discurso conservador y biomédico, que afecta la comprensión, la percepción y la acción de los profesores de EF en equipos multidisciplinarios en el contexto de la Salud Colectiva en el SUS actual

Anti-CFH-associated hemolytic uremic syndrome: do we still need plasma exchange?

BACKGROUND: Between 5 and 50% of atypical hemolytic uremic syndrome (aHUS) cases in children are caused by autoantibodies against complement factor H (CFH). Given the acquired autoimmune nature of the disease, plasma exchange (PE) and various immunosuppressive treatments have been used. More recently, eculizumab has been proposed. METHODS: In this multicenter, retrospective study, we report outcomes of 12 children with anti-FH antibody-associated HUS treated with eculizumab associated with various immunosuppressive regimens. RESULTS: Patients were treated with eculizumab for 15.5 [9.5;23.0] months and 3 received PE or IgG adsorption. Three patients received mycophenolate mofetil (MMF) alone, 1 patient received MMF and steroids, 1 patient received MMF and rituximab, 3 patients received MMF/steroids and rituximab, and 4 patients did not receive any immunosuppression. Anti-FH antibody levels significantly decreased but no difference was observed based on the immunosuppressive regimen. Eculizumab was discontinued in 7/10 patients after 11 [7.5;15.5] months and MMF in 6/8 patients after 36 [35;40] months. Anti-FH titers at MMF discontinuation ranged from 257 to 3425 UI/L. None of these patients relapsed and eGFR at last follow-up was above 70 mL/min/1.73 m2 in all patients. CONCLUSIONS: Eculizumab is effective and safe in inducing and maintaining remission in aHUS secondary to anti-FH antibodies and renders reduction of anti-FH titers less urgent. Anti-FH antibody titers decreased in most patients irrespective of the immunosuppressive treatment chosen, so that a strategy consisting of combining eculizumab with MMF monotherapy seems sufficient at least in non-Indian or less severe forms of anti-FH antibody-associated HUS.

ANCA-Associated Vasculitis with Systemic Thrombotic Microangiopathy: A Review of Literature.

Introduction: Antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) rarely coexist with systemic thrombotic microangiopathy (TMA).The TMA can be in the form of either hemolytic uremic syndrome (HUS) or thrombotic thrombocytopenic purpura (TTP). This review explores the clinical characteristics, histopathological findings, treatment options, and outcomes in patients presenting as AAV with coexisting HUS/TTP. Methods: We conducted a search on the PubMed database and additional searches from January 1998 to September 2022 using the following terms: "ANCA", "Antineutrophil cytoplasmic antibody", "thrombotic thrombocytopenic purpura", "TTP", "thrombotic microangiopathy", "haemolytic uremic syndrome", and "HUS". We excluded articles that described renal-limited TMA. Two authors independently reviewed the full texts and extracted all critical data from the included case reports. Finally, we included 15 cases for this review. Hematological remission and kidney recovery in the form of independence from dialysis was assessed. Results: The median age of the patients was 61 years and a majority of them were females (66.7%). Myeloperoxidase (MPO)-ANCA positivity (66.67%) was more common than proteinase 3 (PR3)-ANCA positivity (33.33%). All patients had laboratory parameters consistent with systemic TMA (HUS or TTP), and only six (out of 11) cases showed histological features of renal TMA. Ten had crescentic glomerulonephritis, and two had advanced degrees of chronicity in histology. Eighty-six percent of cases had hematological remission, and sixty percent of cases became dialysis-independent after treatment. Conclusion: In conclusion, kidney outcome was worse in patients who manifested both AAV and systemic TMA. A paucity of literature regarding this diagnostic quandary calls for avid reporting of such cases.

Assessment of South Asian Pediatric Acute Kidney Injury: Epidemiology and Risk Factors (ASPIRE)-a prospective study on "severe dialysis dependent pediatric AKI".

BACKGROUND: Pediatric acute kidney injury (AKI) is a global health concern with an associated mortality risk disproportionately pronounced in resource-limited settings. There is a pertinent need to understand the epidemiology of pediatric AKI in vulnerable populations. Here, we proposed a prospective study to investigate the epidemiology and associated risk factors of "severe dialysis dependent AKI" in children among South Asian nations which would be the first and largest of its kind. METHODS: The ASPIRE study (part of PCRRT-ICONIC Foundation initiative) is a multi-center, prospective observational study conducted in South Asian countries. All children and adolescents ≤ 18 years of age who required dialysis for AKI in any of the collaborating medical centers were enrolled. Data collection was performed until one of the following endpoints was observed: (1) discharge, (2) death, and (3) discharge against medical advice. RESULTS: From 2019 to 2022, a total of 308 children with severe AKI were enrolled. The mean age was 6.17 years (63% males). Secondary AKI was more prevalent than primary AKI (67.2%), which predominantly occurred due to infections, dehydration, and nephrotoxins. Common causes of primary AKI were glomerulonephritis, hemolytic uremic syndrome, lupus nephritis, and obstructive uropathy. Shock, need for ventilation, and coagulopathy were commonly seen in children with severe AKI who needed dialysis. The foremost kidney replacement therapy used was peritoneal dialysis (60.7%). The mortality rate was 32.1%. CONCLUSIONS: Common causes of AKI in children in South Asia are preventable. Mortality is high among these children suffering from "severe dialysis dependent AKI." Targeted interventions to prevent and identify AKI early and initiate supportive care in less-resourced nations are needed.

STEC colitis mimicking acute severe colitis with life-threatening consequences: a case report.

Acute colitis is a common feature of infection with Shiga-toxin producing Escherichia coli (STEC) and can mimic acute severe ulcerative colitis. Early recognition is important as there is a risk of developing Shiga toxin-induced haemolytic uremic syndrome (STEC-HUS), defined by the triad of microangiopathic haemolytic anemia, thrombocytopenia and organ damage. In severe cases STEC-HUS can cause severe neurological complications and can be fatal. We present a patient with a medical history of refractory ulcerative colitis, where making the diagnosis of STEC-HUS was challenging since the initial clinical presentation was difficult to differentiate from a flare of ulcerative colitis. This case illustrates that STEC induced colitis can mimic acute severe ulcerative colitis. This finding is of utmost clinical importance because of the potential life-threatening complications of STEC-HUS. Therefore it should be excluded promptly in patients with acute severe ulcerative colitis by using multiplex-PCR assay on a faecal sample.

Hot Spot of Complement Factor I Rare Variant p.Ile357Met in Patients With Hemolytic Uremic Syndrome.

Atypical hemolytic uremic syndrome (aHUS) is a rare kidney disease due to a dysregulation of the complement alternative pathway. Complement factor I (CFI) negatively regulates the alternative pathway and CFI gene rare variants have been associated to aHUS with a low disease penetrance. We report 10 unrelated cases of HUS associated to a rare CFI variant, p.Ile357Met (c.1071T>G). All patients with isolated p.Ile357Met CFI missense variant were retrospectively identified among patients included between January 2007 and January 2022 in the French HUS Registry. We identified 10 unrelated patients (70% women; median age at HUS diagnosis, 36.5 years) who carry the same rare variant p.Ile357Met in the CFI gene. Seven patients (cases 1-7) presented with aHUS in the native kidney associated with malignant hypertension in 5 patients. None received a C5 inhibitor. Two of these cases occurred in the peripartum period with complete recovery of kidney function, while 5 of these patients reached kidney failure requiring replacement therapy (KFRT). Four patients with KFRT subsequently underwent kidney transplantation. Three later developed C3 glomerulopathy in their kidney graft, but none had aHUS recurrence. Three other patients (cases 8-10) experienced de novo thrombotic microangiopathy after kidney transplantation, precipitated by various triggers. The rare CFI variant p.Ile357Met appears to be a facilitating genetic factor for HUS and for some forms of secondary HUS.

Mechanism underlying severe deficiency of plasma ADAMTS-13 activity in immune thrombotic thrombocytopenic purpura.

BACKGROUND: Immune-mediated thrombotic thrombocytopenic purpura is caused by autoantibodies against ADAMTS-13, a plasma enzyme that cleaves von Willebrand factor. However, the mechanism resulting in severe deficiency of plasma ADAMTS-13 activity remains controversial. OBJECTIVES: To determine the mechanism of autoantibody-mediated severe deficiency of plasma ADAMTS13 activity in immune-mediated thrombotic thrombocytopenic purpura. METHODS: Fluorescence resonance energy transfer-VWF73 was used to determine plasma ADAMTS-13 activity. Enzyme-linked immunosorbent assay (ELISA) was used to determine anti-ADAMTS-13 immunoglobulin G. ELISA and capillary electrophoresis-based Western blotting were employed to assess plasma ADAMTS-13 antigen. RESULTS: We showed that plasma ADAMTS-13 antigen levels varied substantially in the samples collected on admission despite all showing plasma ADAMTS-13 activity of <10 IU/dL (or <10% of normal level) using either ELISA or Western blotting. More severe deficiency of plasma ADAMTS-13 antigen (<10%) was detected in admission samples by ELISA than by capillary Western blotting. There was a significant but moderate correlation between plasma ADAMTS-13 activity and ADAMTS-13 antigen by either assay method, suggesting that severe deficiency of plasma ADAMTS-13 activity is not entirely associated with low levels of ADAMTS-13 antigen. CONCLUSION: We conclude that severe deficiency of plasma ADAMTS-13 activity primarily resulted from antibody-mediated inhibition, but the accelerated clearance of plasma ADAMTS-13 antigen via immune complexes may also contribute significantly to severe deficiency of plasma ADAMTS-13 activity in a subset of patients with acute immune-mediated thrombotic thrombocytopenic purpura.

A Case of Atypical Hemolytic Uremic Syndrome Triggered by Acute Pancreatitis in a Patient with a Membrane Cofactor Protein (CD46) Genetic Variant.

Atypical hemolytic uremic syndrome (aHUS) is a type of HUS. We herein report a case of aHUS triggered by pancreatitis in a patient with a heterozygous variant of membrane cofactor protein (MCP; P165S), a complement-related gene. Plasma exchange therapy and hemodialysis improved thrombocytopenia and anemia without leading to end-stage kidney disease. This MCP heterozygous variant was insufficient to cause aHUS on its own. Pancreatitis, in addition to a genetic background with a MCP heterozygous variant, led to the manifestation of aHUS. This case supports the "multiple hit theory" that several factors are required for the manifestation of aHUS.

HELLP Syndrome and Differential Diagnosis with Other Thrombotic Microangiopathies in Pregnancy.

Thrombotic microangiopathies (TMAs) comprise a distinct group of diseases with different manifestations that can occur in both pediatric and adult patients. They can be hereditary or acquired, with subtle onset or a rapidly progressive course, and they are particularly known for their morbidity and mortality. Pregnancy is a high-risk time for the development of several types of thrombotic microangiopathies. The three major syndromes are hemolysis, elevated liver function tests, and low platelets (HELLP); hemolytic uremic syndrome (HUS); and thrombotic thrombocytopenic purpura (TTP). Because of their rarity, clinical information and therapeutic results related to these conditions are often obtained from case reports, small series, registries, and reviews. The collection of individual observations, the evolution of diagnostic laboratories that have identified autoimmune and/or genetic abnormalities using von Willebrand factor post-secretion processing or genetic-functional alterations in the regulation of alternative complement pathways in some of these TMAs, and, most importantly, the introduction of advanced treatments, have enabled the preservation of affected organs and improved survival rates. Although TMAs may show different etiopathogenesis routes, they all show the presence of pathological lesions, which are characterized by endothelial damage and the formation of thrombi rich in platelets at the microvascular level, as a common denominator, and thrombotic damage to microcirculation pathways induces "mechanical" (microangiopathic) hemolytic anemia, the consumption of platelets, and ischemic organ damage. In this review, we highlight the current knowledge about the diagnosis and management of these complications during pregnancy.

A Rare Case of Autoimmune Disorder as a Trigger for Atypical Hemolytic Uremic Syndrome.

Autoimmune diseases may act as a trigger for atypical hemolytic uremic syndrome (aHUS). Triggers for aHUS may include autoimmune diseases, infections, metabolic conditions, pregnancy, and transplants. aHUS-mediated injury to various organs, especially kidneys, can be life-threatening. Here, we present the case of a young female who had perinuclear antineutrophil cytoplasmic antibody (p-ANCA)-associated vasculitis and was diagnosed with aHUS. We consider underlying autoimmune p-ANCA-associated vasculitis as a trigger for aHUS in this case.