Atypical hemolytic uremic syndrome in the Tunisian population

Systemic lupus erythematosus presenting with atypical hemolytic uremic syndrome: a case report and review of the literature

Systemic lupus erythematosus (SLE) can present with a diverse array of hematologic manifestations, among which atypical hemolytic uremic syndrome (aHUS) is a rare entity. SLE-triggered aHUS has significant morbidity and mortality without timely intervention, yet its frequency remains uncertain and optimal strategies for complement-directed therapies are largely expert-driven. We performed a comprehensive literature review and present a case of a 23-year-old female newly diagnosed with SLE/class IV lupus nephritis who developed aHUS that rapidly responded to the C5 antagonist, eculizumab. Review of the current literature identified forty-nine published cases of SLE with concurrent aHUS and revealed a predilection for aHUS in younger SLE patients, concurrent presentation with lupus nephritis, anti-dsDNA positivity, and complement system abnormalities. Over seventy percent of cases used eculizumab as complement-directed therapy with a trend towards faster time to improvement in laboratory parameters, though reported outcomes were highly variable. Early recognition of aHUS in SLE is pivotal in guiding appropriate therapeutic interventions, and prompt initiation of eculizumab may reduce the potential morbidity associated with plasmapheresis and additional immunosuppression. While eculizumab showcases promising results, its optimal timing and duration remain elusive. An understanding of a patients' complement genetics could aid management strategies, and ongoing research into complement-targeted therapies offers promising avenues for both SLE and aHUS treatment.

Complement Factor I Gene Variant in an Atypical Hemolytic Uremic Syndrome Triggered by Hypereosinophilia Syndrome

Atypical hemolytic uremic syndrome (aHUS) is a condition characterized by acute kidney injury (AKI), thrombocytopenia, and microangiopathic hemolytic anemia secondary to complement pathway dysregulation. Several triggers have been identified as causing aHUS in genetically susceptible patients; however, hypereosinophilia syndrome (HES)-triggered aHUS has not been reported. In this article, we present a case of aHUS presented with generalized urticarial rashes and angioedema. The initial investigations revealed hypereosinophilia (maximal absolute eosinophil count of 6,840 cells/µL) with normal bone-marrow analyses; hence, idiopathic HES was diagnosed. During hospitalization, the patient developed convulsion, stuporous, and full-blown thrombotic microangiopathy (TMA), with AKI requiring temporary hemodialysis. A kidney biopsy confirmed the existence of renal TMA. Next-generation sequencing of the coding regions of aHUS-related genes was performed, revealing an underlying complement factor I (CFI) deficiency, a heterozygous variant p.P64L of CFI gene. The patient was successfully treated with high-dose steroids and extended duration of plasmapheresis.

Systematic review of atypical hemolytic uremic syndrome biomarkers

BACKGROUND AND OBJECTIVES

Observing biomarkers that affect alternative pathway dysregulation components may be effective in obtaining a new and more rapid diagnostic portrayal of atypical hemolytic uremic syndrome. We have conducted a systematic review on the aHUS biomarkers: C3, C5a, C5b-9, factor B, complement factor B, H, and I, CH50, AH50, D-dimer, as well as anti-CFH antibodies.

METHODS

An exhaustive literature search was conducted for aHUS patient population plasma/serum, collected/reported at the onset of diagnosis. A total of 60 studies were included with the data on 837 aHUS subjects, with at least one biomarker reported.

RESULTS

The biomarkers C3 [mean (SD): 72.1 (35.0), median: 70.5 vs. reference range: 75-175 mg/dl, n = 752]; CH50 [28.3 (32.1), 24.3 vs. 30-75 U/ml, n = 63]; AH50 [27.6% (30.2%), 10% vs. ≥ 46%, n = 23]; and CFB [13.1 (6.6), 12.4, vs. 15.2-42.3 mg/dl, n = 19] were lower among aHUS subjects as compared with the reference range. The biomarkers including C4 [mean (SD): 20.4 (9.5), median: 20.5 vs. reference range: 14-40 mg/dl, n = 343]; C4d [7.2 (6.5), 4.8 vs. ≤ 9.8 μg/ml, n = 108]; CFH [40.2 (132.3), 24.5 vs. 23.6-43.1 mg/dl, n = 123 subjects]; and CFI [8.05 (5.01), 6.55 mg/dl vs. 4.4-18.1 mg/dl, n = 38] were all observed to be within the reference range among aHUS subjects. The biomarkers C5a [mean (SD): 54.9 (32.9), median: 48.8 vs. reference range: 10.6-26.3 mg/dl, n = 117]; C5b-9 [466.0 (401.4), 317 (186-569.7) vs. ≤ 250 ng/ml, n = 174]; Bb [2.6 (2.1), 1.9 vs. ≤ 1.6 μg/ml, n = 77] and D-dimer [246 (65.05), 246 vs. < 2.2 ng/ml, 2, n = 2 subjects] were higher among patients with aHUS compared with the reference range.

CONCLUSION

If a comprehensive complement profile were built using our data, aHUS would be identified by low levels of C3, CH50, AH50, and CFB along with increased levels of C5a, C5b-9, Bb, anti-CFH autoantibodies, and D-dimer. A higher resolution version of the Graphical abstract is available as Supplementary information.

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.

Characteristics of children with sporadic hemolytic uremic syndrome in a single Northern California center

PURPOSE

Hemolytic uremic syndrome (HUS) is a frequent cause of acute kidney injury in children. The aim of this study is to describe our experience at a Northern California center.

METHODS

Medical records of children suffered from HUS (08/99 to 03/09) at University of California Davis Medical Center were reviewed.

RESULTS

Forty-six children (70% girls) were studied, and their median age was 3.5 years. Diarrhea was a presenting symptom in 42 subjects (91%), and hematochezia was present in 31 children (67%). Escherichia coli 0157:H7 was isolated in 20 patients (44%). Thirteen subjects (28%) underwent dialysis for a median of 7 days during their hospitalization. Follow-up was achieved in 36 patients (78.3%) for a median of 16 months. One patient required angiotensin-converting enzyme (ACE) inhibitor for proteinuria but none was on dialysis.

CONCLUSIONS

In our cohort in children with HUS in a single Californian center, long-term complications were uncommon during a median follow-up time of 16 months.