Atypical haemolytic uraemic syndrome and pregnancy: outcome with ongoing eculizumab

Acute Kidney Injury in Pregnancy: The Changing Landscape for the 21st Century

Pregnancy-related acute kidney injury (Pr-AKI) remains a large public health problem, with decreasing incidences in developing countries but seemingly increasing incidences in the United States and Canada. These epidemiologic changes are reflective of the advances in medical and obstetric care, as well as changes in underlying maternal risk factors. The risk factors associated with advanced maternal age, such as hypertension, diabetes, chronic kidney disease, and those associated with reproductive technologies such as multiple gestations, are increasing. Traditional causes of Pr-AKI, such as septic abortions and puerperal sepsis, have been replaced by hypertensive diseases, such as preeclampsia and thrombotic microangiopathies comprising thrombotic thrombocytopenic purpura (TTP) and atypical hemolytic uremic syndrome (aHUS). In this review, we discuss the global impact of Pr-AKI on maternal and fetal outcomes, the predominant etiologies, and key clinical features to distinguish diagnoses, such as preeclampsia/hemolysis elevated liver function test and low platelet (HELLP) syndrome, acute fatty liver disease of pregnancy (AFLP), and other thrombotic microangiopathies. New insights into the pathogenesis of preeclampsia, TTP/aHUS, and AFLP that have unearthed possible therapeutic targets are summarized. We also delve into special consideration needed to give to pyelonephritis and postobstructive causes of Pr-AKI. With each diagnosis, we offer the latest treatment recommendations, such as the positive reports from the use of eculizumab to treat aHUS. In the end, we hope to arm the clinician with the best tools to understand and address this morbid problem that does not seem to be disappearing.

Complement C5-inhibiting therapy for the thrombotic microangiopathies: accumulating evidence, but not a panacea

Thrombotic microangiopathy (TMA), characterized by organ injury occurring consequent to severe endothelial damage, can manifest in a diverse range of diseases. In complement-mediated atypical haemolytic uraemic syndrome (aHUS) a primary defect in complement, such as a mutation or autoantibody leading to over activation of the alternative pathway, predisposes to the development of disease, usually following exposure to an environmental trigger. The elucidation of the pathogenesis of aHUS resulted in the successful introduction of the complement inhibitor eculizumab into clinical practice. In other TMAs, although complement activation may be seen, its role in the pathogenesis remains to be confirmed by an interventional trial. Although many case reports in TMAs other than complement-mediated aHUS hint at efficacy, publication bias, concurrent therapies and in some cases the self-limiting nature of disease make broader interpretation difficult. In this article, we will review the evidence for the role of complement inhibition in complement-mediated aHUS and other TMAs.

A retrospective study of pregnancy-associated atypical hemolytic uremic syndrome

Pregnancy-associated atypical hemolytic uremic syndrome (aHUS) refers to the thrombotic microangiopathy resulting from uncontrolled complement activation during pregnancy or the postpartum period. Pregnancy-associated aHUS is a devastating disease for which there is a limited clinical understanding and treatment experience. Here we report a retrospective study to analyze the clinical and prognostic data of 22 cases of pregnancy-associated aHUS from the Spanish aHUS Registry under different treatments. Sixteen patients presented during the first pregnancy and as many as nine patients required hemodialysis at diagnosis. Identification of inherited complement abnormalities explained nine of the 22 cases, with CFH mutations and CFH to CFHR1 gene conversion events being the most prevalent genetic alterations associated with this disorder (66%). In thirteen of the cases, pregnancy complications were sufficient to trigger a thrombotic microangiopathy in the absence of genetic or acquired complement alterations. The postpartum period was the time with highest risk to develop the disease and the group shows an association of cesarean section with pregnancy-associated aHUS. Seventeen patients underwent plasma treatments with a positive renal response in only three cases. In contrast, ten patients received eculizumab with an excellent renal response in all, independent of carrying or not inherited complement abnormalities. Although the cohort is relatively small, the data suggest that pregnancy-associated aHUS is not different from other types of aHUS and suggest the efficacy of eculizumab treatment over plasma therapies. This study may be useful to improve prognosis in this group of aHUS patients.

Hemolytic Uremic Syndrome in Pregnancy and Postpartum

BACKGROUND

Pregnancy is associated with various forms of thrombotic microangiopathy, including hemolytic uremic syndrome. A previous small French study suggested that pregnancy-associated hemolytic uremic syndrome was to be included in the spectrum of atypical hemolytic uremic syndrome linked to complement alternative pathway dysregulation.

DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS

We sought to retrospectively analyze the presentation, outcome, and frequency of complement alternative pathway gene variants in a larger international (France, United Kingdom, Italy) cohort of patients with pregnancy-associated hemolytic uremic syndrome.

RESULTS

Eighty-seven patients with pregnancy-associated hemolytic uremic syndrome were included. Hemolytic uremic syndrome occurred mainly during the first pregnancy (58%) and in the postpartum period (76%). At diagnosis, 56 (71%) patients required dialysis. Fifty-six (78%) patients underwent plasma exchanges, 21 (41%) received plasma infusions, and four (5%) received eculizumab. During follow-up (mean duration of 7.2 years), 41 (53%) patients reached ESRD, 15 (19%) had CKD, and 18 (28%) patients experienced hemolytic uremic syndrome relapse. Twenty-four patients (27%) received a kidney transplant and a recurrence of hemolytic uremic syndrome occurred in 13 (54%) patients. Variants in complement genes were detected in 49 (56%) patients, mainly in the CFH (30%) and CFI genes (9%).

CONCLUSIONS

Pregnancy-associated hemolytic uremic syndrome and atypical hemolytic uremic syndrome nonrelated to pregnancy have the same severity at onset and during follow-up and the same frequency of complement gene variants.

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.