Atypical hemolytic uremic syndrome: a clinical conundrum

Efficacy of cascade plasmapheresis in comparison with conventional therapeutic plasma exchange for relapsed atypical hemolytic uremic syndrome: A case report

Atypical hemolytic uremic syndrome (aHUS) is a rare and life-threatening disease that is associated with high mortality and morbidity. The incidence of aHUS is about 1 or 2 cases per 1,000,000 per year. Etiology can be either familial or sporadic. The pathogenesis of aHUS involves dysregulation of the alternative complement pathway, with predisposing mutations in complement genes. aHUS has a poor prognosis and a gradual or a relapsing (30%-86%) clinical course. The disease may present at any age but is mostly seen in children and young adults. Therapeutic plasma exchange (TPE) is one of the primary modalities of treatment in aHUS. This report presents the utilization of cascade plasmapheresis and its advantages over TPE in a patient with relapsed aHUS. There was a 73% decrement in antifactor H antibody levels following cascade plasmapheresis.

Atypical hemolytic uremic syndrome in the Colombian Caribbean: its particular characteristics

Introduction

Atypical hemolytic uremic syndrome (aHUS) is a rare and genetically mediated systemic disease most often caused by uncontrolled and chronic complement activation that leads to systemic thrombotic microangiopathy, renal and extra-renal damage.

Materials and methods

This is descriptive, retrospective and multicenter study, which reports demographic, clinical, laboratory, and genetic characteristics, as well as their treatment response and outcome of 20 aHUS patients diagnosed between 2014 and 2018.

Results

Most patients were female adults (75%) and 30% were associated to pregnancy/postpartum, 15% to autoimmune disease, and 65% to infections. Gastrointestinal involvement (75%) was the most frequent extra-renal organ damage. Antenatal mortality and mortality rate were 5% and 10%, respectively. 25% of the patients progressed to end-stage renal disease. In 4/8 of patients treated within 1 week of presentation, eculizumab treatment restored multi-organ function after 4 weeks of treatment. CFH (37%) and CFI (25%) mutations were the most frequent.

Conclusion

This is the first series of aHUS cases of Colombian Caribbean region which reports the clinical and epidemiological characteristics of this condition in this region.

Pregnancy-associated hemolytic uremic syndrome

Pregnancy-associated hemolytic uremic syndrome (P-aHUS) is not an uncommon condition. It is considered a medical emergency that is associated with a high risk of mortality and serious morbidity. End-stage renal disease as a consequence of P-aHUS occurs in >50% of the patients if left untreated; the majority of identified cases (79%) are during the postpartum period. Its mechanism of action is related mainly to the disturbance in the activation of the complement alternative pathway, leading to damage of the microvascular endothelium. The clinical picture of P-aHUS mimics several conditions occurring during post-partum thrombotic microangiopathy, for example, severe pre-eclampsia, hemolysis, elevated liver enzymes, and low platelet count, thrombotic-thrombocytopenic purpura, and acute fatty liver of pregnancy. Genetic analysis of known genetic mutations together with the analysis of anti-CFH antibodies might confirm the diagnosis of aHUS in the post-partum period. The absence of causative genetic mutations does not always exclude a diagnosis of aHUS, since 40% of patients show no known genetic abnormalities. The mainstay of management is supportive care and immediate initiation of plasmapheresis. Eculizumab has been proved to be both safe and effective in inducing and maintaining remission in P-aHUS and it is recommended to be started as soon as the diagnosis is established.

CFH and CFB mutations in Shiga toxin-associated haemolytic uraemic syndrome in a 6-year-old boy

Haemolytic uraemic syndrome (HUS) is most commonly associated with Shiga toxin-producing Escherichia coli (STEC) while the recurrent hereditary atypical (aHUS) form secondary to complement system control protein mutations is relatively rare. A 6-year-old boy with complement factor H (CFH) and factor B (CFB) mutations and a history of bloody diarrhoea and PCR positivity for Shiga toxin was initially diagnosed as STEC+HUS. Acute kidney injury resolved with Eculizumab but he remains with chronic renal failure. Although the exact role of STEC in the pathogenesis of aHUS in this patient is not certain, there seems to be a relationship. However, several issues remain to be explained including the effect of genetic and environmental factors in modifying susceptibility to develop aHUS in some patients following STEC infection.Abbreviations: aHUS: atypical haemolytic uraemic syndrome; ANA: anti-nuclear antibody; ANCA: anti-neutrophil cytoplasmic antibody; ASO: anti-streptolysin O; BUN: blood urea nitrogen; CFB: complement factor B; CFH: complement factor H; EHEC: enterohaemorrhagic Escherichia coli; MCP: membrane co-factor protein; PD: peritoneal dialysis; STEC: Shiga toxin-producing Escherichia coli; STX 1-2: Shiga toxins 1-2.

Glyco-iELISA: a highly sensitive and unambiguous serological method to diagnose STEC-HUS caused by serotype O157

BACKGROUND

Providing proof of presence of Shiga toxin-producing E. coli (STEC) infection forms the basis for differentiating STEC-hemolytic uremic syndrome (HUS) and atypical HUS. As the gold standard to diagnose STEC-HUS has limitations, using ELISA to detect serum antibodies against STEC lipopolysaccharides (LPS) has proven additional value. Yet, conventional LPS-ELISA has drawbacks, most importantly presence of cross-reactivity due to the conserved lipid A part of LPS. The newly described glyco-iELISA tackles this issue by using modified LPS that eliminates the lipid A part. Here, the incremental value of glyco-iELISA compared to LPS-ELISA is assessed.

METHODS

A retrospective study was performed including all pediatric patients (n = 51) presenting with a clinical pattern of STEC-HUS between 1990 and 2014 in our hospital. Subsequently, the diagnostic value of glyco-iELISA was evaluated in a retrospective nationwide study (n = 264) of patients with thrombotic microangiopathy (TMA). LPS- and glyco-iELISA were performed to detect IgM against STEC serotype O157. Both serological tests were compared with each other and with fecal diagnostics.

RESULTS

Glyco-iELISA is highly sensitive and has no cross-reactivity. In the single-center cohort, fecal diagnostics, LPS-ELISA, and glyco-iELISA identified STEC O157 infection in 43%, 65%, and 78% of patients, respectively. Combining glyco-iELISA with fecal diagnostics, STEC infection due to O157 was detected in 89% of patients. In the nationwide cohort, 19 additional patients (8%) were diagnosed with STEC-HUS by glyco-iELISA.

CONCLUSION

This study shows that using glyco-iELISA to detect IgM against STEC serotype O157 has clear benefit compared to conventional LPS-ELISA, contributing to optimal diagnostics in STEC-HUS.

Three months interval therapy of Eculizumab in a patient with atypical hemolytic uremic syndrome with hybrid CFHR1/CFH gene

Pregnancy-associated atypical hemolytic uremic syndrome (P-aHUS) is a rare condition. It is characterized by very high maternal mortality and morbidity. Most cases of P-aHUS (79%) manifest in the postpartum period; this is probably due to the complement's involvement in aHUS pathogenesis. Eculizumab is approved for aHUS treatment, but its use is limited due to cost, unknown duration of treatment, and vague dose intervals to keep patients in remission. In this case report, we present a 26-year-old female with P-aHUS with hybrid CFHR1/CFH gene. Eculizumab was initiated after 5 weeks of being on hemodialysis and plasmapheresis sessions. Full remission successfully achieved after 6th dose of Eculizumab, within 13 weeks of onset of aHUS. Due to financial issues and inability to financially cover the cost, Eculizumab was set in hold. Within 6 months, she suffered recurrence of the disease and Eculizumab was re-instated. After re-inducing full remission, the patient was switched to Eculizumab every 3 months instead of the recommended manufacture dose interval of every 2 weeks. We followed this patient for 3 years and she continued to be in remission based on clinical and laboratory data. In conclusion, achievement of successful and maintenance of remission of P-aHUS in this patient who had limited access to Eculizumab raise the attention of the efficacy of Eculizumab at longer time intervals. However, it is time to consider conducting a long-term study to learn about the safety and efficacy of this approach, which may have a major financial advantage for patients.

Short- and Long-Term Renal Outcome of Hemolytic-Uremic Syndrome in Childhood

Introduction: Hemolytic-uremic syndrome (HUS) is a common cause for intrarenal acute kidney injury in childhood. More than 90% of HUS cases are associated with an infection by Shigatoxin-producing Escherichia coli (STEC) whereas the reminder comprises a heterogeneous group (here classified as Non-STEC-HUS). Renal impairment can persist in patients with HUS. This study presents data from four decades investigating the short- and long-term outcome of HUS in childhood. Materials and Methods: In a retrospective single-center-study clinical and laboratory data of the acute phase and of 1- to 10-year follow-up visits of children with HUS were analyzed. Results: 92 HUS-patients were identified from 1996 to 2014 (STEC-HUS-group: n = 76; Non-STEC-HUS-group: n = 16) and 220 HUS-patients between 1976 and 1995. STEC-HUS was increasingly caused by Non-O157 strains and mortality rate declined over the past decades (1.3 vs. 9.5%). Renal sequelae persisted more often in the group 1976-1995 (39.3%) than in the group 1996-2014 (28.3%), but more than 50% of all patients were lost to follow-up. Conclusion: Although renal outcome has improved over the investigated last decades, patients with HUS still face a high risk of permanent renal damage. These findings underline the importance of a consequent long-term follow-up in HUS-patients.