Pregnancy-associated atypical haemolytic uraemic syndrome in the postpartum period: a case report and review of the literature

A Rare Case of Atypical Hemolytic Uremic Syndrome (HUS) in an Adult Male: A Catastrophic Presentation

Atypical hemolytic uremic syndrome (HUS) is extremely rare in adults. HUS is characterized by hallmark features of microangiopathic hemolytic anemia, thrombocytopenia, and acute renal injury. Atypical HUS (aHUS) is caused by uncontrolled complement activation. The complement activation can be triggered by infections such as Streptococcus pneumoniae or influenza, pregnancy, malignancy, cytotoxic drugs, organ transplants, or autoimmune diseases. Genetic mutations and autoantibodies have been found to play a crucial role in the pathogenesis of dysregulated complement activity. The majority of cases of atypical HUS due to invasive S. pneumoniae infection are more commonly seen in children. We present a case of S. pneumoniae HUS (Sp-HUS) presenting with multiorgan failure, disseminated intravascular coagulation (DIC), and limb ischemia in an adult. This case highlights the importance of considering S. pneumoniae HUS (Sp-HUS) in the differential diagnosis of thrombotic microangiopathies (TMA) in adults.

Successful treatment with eculizumab in a patient with pregnancy-associated atypical hemolytic uremic syndrome

Pregnancy-associated atypical haemolytic uraemic syndrome is a rare and potentially lethal complement-mediated disorder. It can mimic preeclampsia, gestational hypertension, thrombotic thrombocytopenic purpura and hemolysis, elevated liver enzymes and low platelets syndrome. Thus, it can be hard to distinguish pregnancy-associated atypical haemolytic uraemic syndrome from other causes in peri/post-partum women presenting with features of microangiopathic haemolytic anemia, thrombocytopenia and acute kidney injury. We present a case of a 35-year-old woman in her third pregnancy at 32 weeks' gestation who underwent caesarean section due to fetal distress. She developed severe renal impairment, thrombocytopenia and neurologic symptoms within 24 hours after delivery. A diagnosis of pregnancy-associated atypical haemolytic uraemic syndrome was provided, and treatment with plasma therapy followed by eculizumab was initiated. A rapid improvement of both clinical and laboratory parameters was observed. This case demonstrates the significance of early initiation of anti-complement therapy to prevent irreversible renal damage and possible death in women with pregnancy-associated atypical haemolytic uraemic syndrome.

A Rare Case of Atypical Hemolytic Uremia Syndrome Triggered by Influenza Vaccination

Atypical hemolytic uremic syndrome (aHUS) occurs in patients with defective alternative complement pathways, making them susceptible to thrombotic microangiopathy (thrombocytopenia, intravascular hemolysis, and renal failure), and is usually triggered by infectious agents. Influenza and Streptococcus pneumonia are known triggers for aHUS. However, influenza vaccination triggering aHUS is rarely reported. We present a 30-year-old male who presented with chills, abdominal discomfort, and night sweats after receiving the influenza vaccine. The patient had thrombocytopenia, elevated creatinine, blood urea nitrogen, liver enzymes, and bilirubin with schistocytes with peripheral smear. ADAMTS13 activity was normal so the patient was diagnosed with aHUS. The patient improved with eculizumab and was ultimately found to have a mutation in CD46, which made him susceptible to aHUS. This case shows patients with dysregulated alternative complement pathways may be predisposed to develop aHUS after receiving influenza vaccination.

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.

Pregnancy-Associated Atypical Hemolytic Uremic Syndrome: A Systematic Review

OBJECTIVE

To evaluate disease presentation, diagnosis, treatment, and clinical outcomes in pregnancy-associated atypical hemolytic uremic syndrome (aHUS).

DATA SOURCES

We searched PubMed, MEDLINE, Cochrane Library, ClinicalTrials.gov, Web of Science, EMBASE and Google Scholar, from inception until March 2018.

METHODS OF STUDY SELECTION

We included English-language articles describing aHUS in pregnancy or postpartum. The diagnosis of aHUS was characterized by hemolysis, thrombocytopenia, and renal failure and was distinguished from typical diarrhea-associated hemolytic uremic syndrome. Patients were excluded if individual data could not be obtained, the diagnosis was unclear, or an alternative etiology was more likely, such as thrombotic thrombocytopenic purpura or Shiga toxin-producing Escherichia coli. Reports were appraised by two reviewers, with disagreements adjudicated by a third reviewer.

TABULATION, INTEGRATION, AND RESULTS

The search identified 796 articles. After review of titles, abstracts, and full text, we identified 48 reports describing 60 unique cases of pregnancy-associated aHUS, with 66 pregnancies. Twelve cases involved pregnancy in women with known aHUS, and 54 cases involved first-episode pregnancy-associated aHUS. Women with known aHUS, particularly those with baseline creatinine at or above 1.5 mg/dL, had a high rate of adverse pregnancy outcomes. For first-episode pregnancy-associated aHUS, diagnosis most often occurred postpartum (94%), after a cesarean delivery (70%), in nulliparous women (58%). Preceding obstetric complications were common and included fetal death, preeclampsia, and hemorrhage. Diagnosis was usually made clinically, based on the triad of microangiopathic hemolysis, thrombocytopenia, and renal failure. Additional testing included renal biopsy, complement genetic testing, and ADAMTS13 (a disintegrin and metalloproteinase with a thrombospondin type 1 motif, member 13) testing. Treatment modalities included corticosteroids, plasma exchange, dialysis, and eculizumab. More women with first-episode pregnancy-associated aHUS achieved disease remission when treated with eculizumab, compared with those not treated with eculizumab (88% vs 57%, P=.02).

CONCLUSION

Pregnancy-associated aHUS usually presents in the postpartum period, often after a pregnancy complication, and eculizumab is effective for achieving disease remission.

SYSTEMATIC REVIEW REGISTRATION

PROSPERO, CRD42019129266.

Complement-Mediated Disorders in Pregnancy

Complement-mediated disorders in pregnancy span a large spectrum and have been implicated in all three complement pathways: classical, lectin, and alternative. Our understanding of these disorders in recent years has advanced due to a better understanding of complement regulatory proteins, such as complement factor H, complement factor I, membrane cofactor protein, and thrombomodulin that particularly affect the alternative complement pathway. Enthusiasm in genotyping for mutations that encode these proteins has allowed us to study the presence of genetic variants which may predispose women to develop conditions such as pregnancy-associated hemolytic uremic syndrome (P-aHUS), thrombotic thrombocytopenic purpura, preeclampsia/hemolysis, elevated liver enzymes, low platelets (HELLP), systemic lupus erythematosus/antiphospholipid syndrome, and peripartum cardiomyopathy. The advent of the anti-C5-antibody eculizumab to quench the complement cascade has already proven in small case series to improve maternal kidney outcomes in complement-mediated obstetric catastrophes such as P-aHUS and HELLP. In this review, we will detail the pathogenesis behind these complement-mediated pregnancy disorders, the role of complement variants in disease phenotype, and the most up-to-date experience with eculizumab in this population.

Complement Activation and Thrombotic Microangiopathies

BACKGROUND AND OBJECTIVES

Atypical hemolytic uremic syndrome is a form of thrombotic microangiopathy caused by dysregulation of the alternative complement pathway. There is evidence showing complement activation in other thrombotic microangiopathies. The aim of this study was to evaluate complement activation in different thrombotic microangiopathies and to monitor treatment response.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

Complement activation was assessed by exposing endothelial cells to sera or activated-patient plasma-citrated plasma mixed with a control sera pool (1:1)-to analyze C5b-9 deposits by immunofluorescence. Patients with atypical hemolytic uremic syndrome (n=34) at different stages of the disease, HELLP syndrome (a pregnancy complication characterized by hemolysis, elevated liver enzymes, and low platelet count) or severe preeclampsia (n=10), and malignant hypertension (n=5) were included.

RESULTS

Acute phase atypical hemolytic uremic syndrome-activated plasma induced an increased C5b-9 deposition on endothelial cells. Standard and lower doses of eculizumab inhibited C5b-9 deposition in all patients with atypical hemolytic uremic syndrome, except in two who showed partial remission and clinical relapse. Significant fibrin formation was observed together with C5b-9 deposition. Results obtained using activated-plasma samples were more marked and reproducible than those obtained with sera. C5b-9 deposition was also increased with samples from patients with HELLP (all cases) and preeclampsia (90%) at disease onset. This increase was sustained in those with HELLP after 40 days, and levels normalized in patients with both HELLP and preeclampsia after 6-9 months. Complement activation in those with malignant hypertension was at control levels.

CONCLUSIONS

The proposed methodology identifies complement overactivation in patients with atypical hemolytic uremic syndrome at acute phase and in other diseases such as HELLP syndrome and preeclampsia. Moreover, it is sensitive enough to individually assess the efficiency of the C5 inhibition treatment.

Pregnancy-induced atypical haemolytic uremic syndrome: A new era with eculizumab

Pregnancy is a well-recognised trigger of atypical haemolytic syndrome (P-aHUS) and often occurs in the post-partum period. Similar to atypical haemolytic uremic syndrome, it carries a poor prognosis with high morbidity particularly in the form of renal failure. Early recognition and intervention is crucial in its management particularly with the recent availability of eculizumab, a humanized monoclonal antibody to complement component C5, which has demonstrated drastic improvement in prognosis. The issue, however, is arriving at a timely diagnosis given the considerable amount of overlap in the clinical and biochemical manifestation of P-aHUS, HELLP syndrome (haemolysis, elevated liver enzyme and low platelet count) and other hypertensive disorders of pregnancy. We present a case report and literature review that highlights the clinical conundrum of arriving at the diagnosis. We also highlight the importance of early management of P-aHUS with eculizumab and its impact on improving morbidity.

HUS and atypical HUS

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy characterized by intravascular hemolysis, thrombocytopenia, and acute kidney failure. HUS is usually categorized as typical, caused by Shiga toxin-producing Escherichia coli (STEC) infection, as atypical HUS (aHUS), usually caused by uncontrolled complement activation, or as secondary HUS with a coexisting disease. In recent years, a general understanding of the pathogenetic mechanisms driving HUS has increased. Typical HUS (ie, STEC-HUS) follows a gastrointestinal infection with STEC, whereas aHUS is associated primarily with mutations or autoantibodies leading to dysregulated complement activation. Among the 30% to 50% of patients with HUS who have no detectable complement defect, some have either impaired diacylglycerol kinase ε (DGKε) activity, cobalamin C deficiency, or plasminogen deficiency. Some have secondary HUS with a coexisting disease or trigger such as autoimmunity, transplantation, cancer, infection, certain cytotoxic drugs, or pregnancy. The common pathogenetic features in STEC-HUS, aHUS, and secondary HUS are simultaneous damage to endothelial cells, intravascular hemolysis, and activation of platelets leading to a procoagulative state, formation of microthrombi, and tissue damage. In this review, the differences and similarities in the pathogenesis of STEC-HUS, aHUS, and secondary HUS are discussed. Common for the pathogenesis seems to be the vicious cycle of complement activation, endothelial cell damage, platelet activation, and thrombosis. This process can be stopped by therapeutic complement inhibition in most patients with aHUS, but usually not those with a DGKε mutation, and some patients with STEC-HUS or secondary HUS. Therefore, understanding the pathogenesis of the different forms of HUS may prove helpful in clinical practice.