Hemoglobin cast nephropathy: a rare but serious complication of hemolysis in a pediatric patient.

BACKGROUND: Intravascular hemolysis is a serious and rare condition in children and causes the release of hemoglobin and heme into circulation, which have proinflammatory properties. These substances lead to inflammation, oxidative stress, apoptosis, and organelle dysfunction that lead to acute kidney injury (AKI). We report a pediatric case diagnosed with hemolysis-associated hemoglobin cast nephropathy due to autoimmune hemolytic anemia. CASE: A 4-year-old boy, who was admitted to another hospital with complaints of fever and dark urine for one day, developed anemia and kidney failure in the follow-up, was referred to our hospital. In physical examination, pallor and icterus on the sclera were noted. The patient had low hemoglobin and haptoglobin levels concomitant with high levels of serum lactate dehydrogenase, urea and creatinine. A peripheral blood smear showed marked spherocytes without schistocytes. A kidney biopsy was performed due to ongoing overt hemolysis and dialysis requirement, which showed findings consistent with hemoglobin cast nephropathy. Although the initial polyspecific direct antiglobulin test (DAT) was negative, due to persistent intravascular hemolysis DAT was studied monospecifically and showed IgM antibody positivity. Therefore, a diagnosis of autoimmune hemolytic anemia was made, and corticosteroid treatment was started. Hemolysis immediately ceased and the need for erythrocyte transfusion and dialysis disappeared. CONCLUSIONS: Acute kidney injury associated with hemoglobin cast nephropathy is an extremely rare condition in childhood. Although the initial course is severe and potentially life-threatening, the prognosis is favorable with the treatment of the underlying cause and management of AKI. Therefore, pediatricians should be aware of this rare clinical entity during clinical practice.

Exploring the Heterogeneity of IgE-Mediated Food Allergy through Latent Class Analysis.

INTRODUCTION: Food allergy (FA) is a heterogeneous disease with multiple morbidities and a huge burden for patients and healthcare systems. Variable manifestations, comorbidities (atopic dermatitis [AD], asthma, and/or allergic rhinitis [AR]), severity (anaphylaxis), and outcomes suggest the existence of different endotypes that cluster analyses may reveal. In this study, we aimed to investigate distinct subgroups among patients with FAs using data from 524 children/adolescents. METHODS: 524 patients with IgE-mediated FA (353 male [67%]; median age 4.4 years [IQR:3.0-6.8]), 354 (68%) had multiple FA. The history of AD, asthma, AR, and anaphylaxis was recorded in 59.4%, 35.5%, 24.2%, and 51.2% of the patients, respectively. Latent class analysis was carried out to distinguish clinical FA phenotypes using five potential markers of allergy severity (single/multiple FA, never/inactive/current asthma and AD, AR, and anaphylaxis). RESULTS: Three distinct phenotypes were identified: (1) multiple FA with eczema and respiratory multimorbidity (42%), (2) multiple FA with persistent eczema (34%), and (3) single FA with respiratory multimorbidity without eczema (24%). Compared with the single FA cluster, the prevalence of AD was significantly higher in multiple FA groups. Cluster 1 had the highest frequency of AR and allergic asthma, and the lowest rate of total tolerance of FA. DISCUSSION: We put forward the hypothesis of underlying pathogenesis according to the clinical phenotypes. While skin barrier defect may play a dominant role in the pathogenesis in Cluster 2, immune dysregulation may be dominant in Cluster 3. In Cluster 1, the most severe group, a combination of both skin barrier defects and immune dysregulation may be responsible for the clinical features.