Alectinib-induced Hemolytic Anemia with Positive Direct Antiglobulin Test in a Patient with Lung Adenocarcinoma: A Possible Drug-drug Interaction Effect.

Recent studies have reported that direct antiglobulin test (DAT) results were negative in cases of alectinib-induced hemolytic anemia with abnormal red blood cell (RBC) morphology. We herein report the case of a 72-year-old female patient who was diagnosed with alectinib-induced hemolytic anemia who - in contrast to previous reports - showed a positive DAT result. After discontinuing famotidine and alectinib, the DAT results turned negative; however, when alectinib was resumed, hemolysis recurred. Although alectinib-induced hemolytic anemia has been previously thought to be associated with abnormal morphological changes of the RBCs, we suggest that alectinib-induced anemia may manifest as DAT-positive immune hemolytic anemia because of a complementary effect with other drugs.

Erythrophagocytosis in autoimmune immunoglobulin A-mediated hemolysis.

INTRODUCTION: Warm antibody-mediated autoimmune hemolysis (WAIHA) is most often due to immunoglobulin G (IgG) antibodies and is detected by direct antiglobulin test (DAT). However, about 10% cases of hemolytic anemia are DAT negative. Herein, we describe a patient with DAT-negative hemolytic anemia due to an anti-IgA antibody. We investigate if isolated IgA can promote erythrophagocytosis. METHODS: We isolated patient and control IgA on Jacalin agarose. Isolated IgA was used to sensitize healthy ABO/Rh-matched donor red blood cells (RBC). Antibody binding was examined by flowcytometry. The effect of IgA on erythrophagocytosis was evaluated using Macrophage colony stimulating factor 1 (M-CSF)-differentiated autologous macrophages by Giemsa staining and immunofluorescence microscopy. RESULTS: We show that isolated IgA from the serum can bind to red cells. In addition, RBCs were phagocytosed efficiently by autologous macrophages in the presence of patient IgA. CONCLUSION: Our results show that IgA antibodies are capable of inducing erythrophagocytosis like IgG antibodies in the absence of complement fixation.

Strategies to overcome the diagnostic challenges of autoimmune hemolytic anemias.

INTRODUCTION: The direct antiglobulin test (DAT) or Coombs test is the cornerstone of the diagnosis of autoimmune hemolytic anemia (AIHA). It can be performed by several methods with different sensitivity and specificity and enables the distinction of warm, cold, and mixed forms, which require different therapies. AREAS COVERED: The review describes the different DAT methods, including the tube test with monospecific antisera, microcolumn and solid phase methods that are routinely accessible in most laboratories. Additional investigations include the use of cold washes and low ionic salt solutions, the identification of auto-Ab specificity and thermal range, the study of the eluate, and the Donath-Landsteiner test, available in most reference laboratories. Experimental techniques are the dual-DAT, flow cytometry, ELISA, immuno-radiometric assay, and mitogen-stimulated DAT, which may help the diagnosis of DAT-negative AIHAs, a clinical challenge with delayed diagnosis and possible improper therapy. Further diagnostic challenges include the correct interpretation of hemolytic markers, the infectious and thrombotic complications, and the possible underlying conditions (lymphoproliferative disorders, immunodeficiencies, neoplasms, transplants, and drugs). EXPERT OPINION: These diagnostic challenges may be overcome by a 'hub' and 'spoke' organization among laboratories, a clinical validation of experimental techniques, and a continuous dialogue between clinicians and immune-hematologic laboratory experts.

DAT-Negative Autoimmune Hemolytic Anemia.

Hematologists often rely on the results of a positive direct antiglobulin test to confirm a diagnosis of autoimmune hemolytic anemia, but immune hemolytic anemia can occur when no immunoglobulin is detectable by routine methods. Negative DATs in these patients may be due to a small quantity of IgG on their red blood cells (RBCs) (below detectable levels), or when low-affinity anti-IgG is present, or when the autoantibodies are IgA or IgM in nature. A panel of tests developed to detect immunoglobulins on these patients' RBCs may be performed in a few specialized laboratories. These tests can be helpful in instances whereby the clinical picture of AIHA seems obvious, but the laboratory values are misleading.

Review: Effects of anti-CD38 monoclonal antibodies on red blood cell transfusion and interventions.

BACKGROUND: Highly expressed in almost all myeloma cells, CD38 is an attractive treatment target. AIM: Anti-CD38 monoclonal antibodies have been approved for first-line treatment in non-transplantable multiple myeloma (MM) patients. MATERIALS AND METHODS: However, it has been found in clinical use that anti-CD38 monoclonal antibodies bind to CD38 on red blood cells (RBCs) and cause panagglutination in indirect antiglobulin test (IAT), resulting in false positives of IAT (Transfusion, 55, 2015 and 1545; Transfusion, 55, 2015 and 1555). RESULT: Thereby, interfering with blood bank testing and leading to the delay of further diagnosis and treatment. CONCLUSION: With more and more patients receiving anti-CD38 treatment, it is of great importance to recognize this problem and optimize relevant diagnosis and treatment procedures to prevent RBC transfusion delays and reduce laboratory costs.

In from the cold: M-protein light chain glycosylation is positively associated with cold agglutinin titer levels.

BACKGROUND: Primary cold agglutinin disease (CAD) is a monoclonal antibody (M-protein) and complement-mediated chronic hemolytic disease process. Antibody glycosylation can play a role in both antibody half-life and complement fixation. Recently, M-protein light chain (LC) glycosylation has been shown to be associated with AL amyloidosis. We hypothesized that M-protein LC glycosylation is also associated with cold agglutinin (CA) titers and CA-mediated hemolysis. STUDY DESIGN AND METHODS: A cross-sectional study of patients undergoing CA titer evaluation underwent mass spectrometric analysis for M-proteins and M-protein LC glycosylation. A subset of serum samples also underwent evaluation for the ability to trigger cold hemolysis in vitro. M-protein and M-protein LC glycosylation rates were compared across CA titer groups, clinical diagnosis, direct antiglobulin testing (DAT) results, and cold in vitro hemolysis rates. RESULTS: Both M-protein and M-protein LC glycosylation rates significantly differed across CA titer groups with the highest rates in those with elevated CA titers. M-protein LC glycosylation occurred almost exclusively on IgM kappa M-proteins and was significantly associated with positive DAT results and a clinical diagnosis of CAD. Cold in vitro hemolysis was demonstrated in two patients who both had a CA titer of more than 512 but there was no significant association with CA titer group or M-protein LC glycosylation status. CONCLUSION: M-protein LC glycosylation is significantly associated with higher CA titer levels. Given the role that antibody glycosylation can play in antibody half-life and complement fixation, further studies are needed to clarify the effects of LC glycosylation within the context of CAD.

Defining autoimmune hemolytic anemia: a systematic review of the terminology used for diagnosis and treatment.

The terminology applied to autoimmune hemolytic anemia (AIHA) seems inconsistent. We aimed to evaluate the consistency of definitions used for diagnosis and treatment. In this systematic review of literature from January 2006 to December 2015, we assessed heterogeneity in the definition of AIHA and its subtypes, refractory disease, disease phase, severity, criteria for treatment response, and response durability. A Medline search for anemia, hemolytic, autoimmune was supplemented with keyword searches. Main exclusions were conference abstracts, animal and non-English studies, and studies with <10 cases. Of 1371 articles retrieved, 1209 were excluded based on titles and abstracts. Two authors independently reviewed 10% and 16% of abstracts and full papers, respectively. After full-paper review, 84 studies were included. AIHA was most frequently (32 [52%] of 61) defined as hemolytic anemia with positive direct antiglobulin test (DAT) and exclusion of alternatives, but 10 of 32 also recognized DAT-negative AIHA. A lower threshold for diagnosis of DAT-negative AIHA was observed in literature on chronic lymphocytic leukemia. Definitions of anemia, hemolysis, and exclusion criteria showed substantial variation. Definitions of primary/secondary cold agglutinin disease/syndrome were not consistent. Forty-three studies provided criteria for treatment response, and other than studies from 1 center, these were almost entirely unique. Other criteria were rarely defined. Only 7, 0, 3, 2, 2, and 3 studies offered definitions of warm AIHA, paroxysmal cold hemoglobinuria, mixed AIHA, AIHA severity, disease phase, and refractory AIHA, respectively. Marked heterogeneity in the time period sampled indicates the need to standardize AIHA terminology.

Avaliação da validação da pesquisa de anticorpos irregulares no Hemocentro Regional de Montes Claros / Validation assessment of irregular antibodies investigation at the Regional Blood Center in Montes Claros City / Evaluación de la validación de la búsqueda de anticuerpos irregulares em la Región Hemocentro de Montes Claros

Objetivo: Analizar lavalidación de la detección de anticuerpos irregulares (PAI) mediante el uso del reactivo de control de Coombs en muestras de sangre tomadas de Febrero 2015 a Agosto 2016. Métodos: Estudio de naturaleza observacional, retrospectivo y prospectivo, con los procedimientos técnicos de carácter documental, que se sucederá em Laboratorio de Inmunohematología del Hemocentro Regional de Montes Claros - MG. Resultados: Se observó durante la encuesta que después de la no validación de algunos testes y sucedida la repetición del mismos individuos, no se ha encontrado la validación, por lo tanto requeiendo otra repetición hasta que la validación de la muestra. Esto plantea la posibilidad de interferencia que no sea el conocido y discutido, ya que la repetición se realiza aisladamente el análisis crítico de todos los pasos del proceso. Conclusión: El bajo porcentaje de resultados no validados ratifica la prueba de validación antiglobulínico es un buen método para confirmar el resultado de la búsqueda de anticuerpos irregulares

Objetivo: Analisar a validação da pesquisa de anticorpos irregulares (PAI) através da utilização do reagente Controle de Coombs em amostras sanguíneas coletadas de Fevereiro de 2015 à Agosto de 2016. Métodos: Estudo de natureza observacional, retrospectiva e prospectiva, apresentando procedimentos técnicos de caráter documental, a ser realizado no Laboratório de Imunohematologia do Hemocentro Regional de Montes Claros - MG. Resultados: Foi observado durante a pesquisa que após a não validação de alguns testes e realizada a repetição dos mesmos isoladamente, não foi constatado a validação sendo necessário outra repetição até que essa amostra validasse. Esse fato levanta a possibilidade de outras interferências além das conhecidas e discutidas, uma vez que a repetição foi realizada isoladamente analisando criticamente todas as etapas do processo. Conclusão: O baixo percentual de resultados não validados ratifica que o teste de validação antiglobulínico é um bom método para confirmar o resultado da pesquisa de anticorpos irregulares

Objective: The study's purpose has been to assess the validation of irregular antibodies investigation using the Coombs control reagent in blood samples collected over the period from February 2015 to August 2016. Methods: It is a observational, retrospective and prospective study, which presents technical procedures bearing a documentary character, and that was performed at the Laboratory of Immunohematology from the Regional Blood Center in Montes Claros-MG. Results: During the research, it was observed that after the non-validation of some tests and its repetition was then performed alone; the validation was not verified and once again a repetition was necessary until this sample was defined as validated. This fact raises the possibility of other interferences beyond those both known and discussed; bearing in mind that the repetition was carried out in isolation and also all stages of the process were performed under scrutiny. Conclusion: The low percentage of non-validated results ratifies that the antiglobulin validation test is a good method to confirm the result of the search for irregular antibodies

Distinct effects of daratumumab on indirect and direct antiglobulin tests: a new method employing 0.01 mol/L dithiothreitol for negating the daratumumab interference with preserving K antigenicity (Osaka method).

BACKGROUND: There is an increasing demand for daratumumab (DARA), an immunoglobulin (Ig)G1κ monoclonal antibody (MoAb) that recognizes CD38, to manage relapsed or refractory multiple myeloma (MM) patients. However, DARA leads to positive and panreactive agglutination reactions in indirect antiglobulin tests (IATs) in vitro (the DARA interference). In addition, effects of DARA on red blood cells (RBCs) in vivo remains elusive. STUDY DESIGN AND METHODS: To develop a new method to negate the DARA interference, the effects of various concentrations of dithiothreitol (DTT) on RBC CD38 and Kell antigenicity in combination with an automatic blood cell washing centrifuge were compared with the AABB standard procedure in parallel. Moreover, direct antiglobulin tests (DATs) for RBCs in DARA-treated MM patients were examined. RESULTS: A quantity of 0.01 mol/L DTT as well as the AABB procedure (equivalent to 0.15 mol/L DTT in our procedure) markedly reduced the reactivity of phycoerythrin-mouse anti-CD38 MoAb and DARA with RBCs. In sharp contrast to the AABB procedure, 0.01 mol/L DTT partially preserved K antigenicity and allowed the determination of phenotype of K antigen even in the presence of the DARA interference. In contrast, DAT for RBCs obtained from MM patients showed a weak positive or negative reaction. Immunoblotting further indicated that DARA induced loss of CD38 in vivo. CONCLUSION: A simple and reliable method to negate the DARA interference with partially preserving Kell antigenicity is proposed (Osaka method). CD38 antigenicity is susceptible to 0.01 mol/L DTT treatment even in the presence of DARA. Our data also demonstrate distinct effects of DARA on IAT in vitro and DAT in vivo.

Diagnosis and management of newly diagnosed childhood autoimmune haemolytic anaemia. Recommendations from the Red Cell Study Group of the Paediatric Haemato-Oncology Italian Association.

Autoimmune haemolytic anaemia is an uncommon disorder to which paediatric haematology centres take a variety of diagnostic and therapeutic approaches. The Red Cell Working Group of the Italian Association of Paediatric Onco-haematology (Associazione Italiana di Ematologia ed Oncologia Pediatrica, AIEOP) developed this document in order to collate expert opinions on the management of newly diagnosed childhood autoimmune haemolytic anaemia.The diagnostic process includes the direct and indirect antiglobulin tests; recommendations are given regarding further diagnostic tests, specifically in the cases that the direct and indirect antiglobulin tests are negative. Clear-cut definitions of clinical response are stated. Specific recommendations for treatment include: dosage of steroid therapy and tapering modality for warm autoimmune haemolytic anaemia; the choice of rituximab as first-line therapy for the rare primary transfusion-dependent cold autoimmune haemolytic anaemia; the indications for supportive therapy; the need for switching to second-line therapy. Each statement is provided with a score expressing the level of appropriateness and the agreement among participants.

Risk factor analysis of autoimmune hemolytic anemia after allogeneic hematopoietic stem cell transplantation in children.

Autoimmune hemolytic anemia (AIHA) is a clinically relevant complication after allogeneic hematopoietic stem cell transplantation (HSCT). Currently, there is no established consensus regarding the optimal therapeutic approach. Whether AIHA contributes to increased mortality is still somewhat controversial.We investigated the incidence, risk factors, and outcome of post-transplant AIHA in 265 consecutive pediatric patients undergoing allo-HSCT over a 17-year period. Onset of AIHA was calculated from the first documented detection of AIHA by either clinical symptoms or positive direct agglutinin test. Resolution of AIHA was defined as normalization of hemoglobin and biochemical markers of hemolysis with sustained transfusion independence.We identified 15 cases of AIHA after allo-HSCT (incidence rate, 6%). Ten (67%) of these patients had a positive direct antiglobulin test. Data were obtained for 9 boys and 6 girls after a median follow-up of 53 months (range 4-102). The median age was 5.1 years (range 0.5-15.4) at the time of HSCT and the median time to emergence was 149 days (range 42-273). No significant risk factor for post-transplant AIHA has emerged from our data to date. In the majority (14 of 15; 93%) of AIHA patients, multiple agents for treatment were required, with 12 of 15 (80%) patients achieving complete resolution of AIHA. No splenectomy was performed in any of our patients.For various reasons, post-transplantation AIHA poses an extraordinary challenge to transplant physicians. Despite the advancements in diagnostic tools, therapeutic challenges remain due to the myriad interacting pathways in AIHA.

Caracterización de los antígenos y anticuerpos eritrocitarios en pacientes en espera de trasplante renal / Red blood cell antigens and antibodies in patients awaiting renal transplantation

Introducción: la importancia de los grupos sanguíneos para la terapia transfusional y el trasplante es bien conocida. La presencia de anticuerpos eritrocitarios puede mediar reacciones transfusionales hemolíticas severas y rechazo de trasplante. Objetivo: caracterizar los antígenos y anticuerpos eritrocitarios en pacientes en espera de trasplante renal.Métodos: se realizó un estudio prospectivo en 980 pacientes en espera de trasplante renal considerados aptos para trasplante, en el periodo comprendido entre julio de 2013 y julio de 2014. Se investigó la frecuencia de los grupos sanguíneos ABO, Rh (DCcEe), Kell (K), Duffy, Kidd y Lewis y se realizó la pesquisa de auto y de aloanticuerpos eritrocitarios a través de las prueba de antiglobulina directa e indirecta (Coombs) y la técnica de polietilenglicol. Resultados : el grupo sanguineo 0 fue el más frecuente, seguido del A, el B y el AB. Dentro de los fenotipos RhD positivos, el DCCee predominó en los individuos blancos y el Dccee en los no blancos. El RhD negativo (ccee) fue más frecuente en blancos que en no blancos. La distribucion del antigeno Kell fue similar en ambos grupos. Se identificaron 14 pacientes (1,4 por ciento) con prueba de Coombs directa positiva, y aloanticuerpos eritrocitarios en 35 pacientes, para una frecuencia de aloinmunización eritrocitaria del 3,6 por ciento. Predominaron los anticuerpos anti - Rh y contra el antigeno Kell. La técnica de polietilenglicol detectó un mayor número de anticuerpos que la PAI, especialmente contra el antigeno RhD, aunque la comparación no fue estadisticamente significatica. Conclusiones: la frecuencia de aloinmunización eritrocitaria es menor que las comunicadas en otros estudios y se relacionó con los antecedentes transfusionales. Se recomienda realizar la pesquisa de auto y aloanticuerpos eritrocitarios a todos los pacientes con enfermedad renal crónica en lista de espera de trasplante(AU)

Introduction: The importance of blood groups in transfusion therapy and transplant is very well known. The presence of red blood cell antibodies can mediate severe hemolytic transfusion reactions and transplant rejection. Objective: To characterize red blood cell antigens and antibodies in patients awaiting renal transplantation. Methods: A prospective study in 980 patients in waiting list for renal transplantation in the period from July, 2013 to July, 2014 was carried out. The frequency of ABO, Rh (DCcEe), Kell (K), Duffy, Kidd and Lewis blood groups, and the screening of red blood cells auto and alloantibodies by the direct and indirect antiglobulin test (Coombs) and the polietilenglicol technique were investigated. Results: Blood group O was the most frequent followed by A, B and AB. DCCee phenotype was frequent in white individuals and Dccee in non-white. RhD negative (ccee) was more frequent in whites than in non-whites. Distribution of Kell antigen was similar in both groups. Direct antiglobulin test was positive In 14 patients (1,4 percent) and red blood cell alloantibodies were identified in 35 patients for a frequency of alloimmunization of 3,6 percent. Anti-Rh anti-K antibodies were the alloantibodies most frequently identified. The polietilenglicol technique detected a higher number of antibodies than the indirect antiglobulin test, specially against RhD antigen, although the comparison was not statistically significant. Conclusions: The frequency of alloimmunization is smaller than those communicated in other studies which was related to transfusion records. A periodic red blood cell auto and alloantibodies screening is recommended in all patients awaiting renal transplantation(AU)

Direct Coombs Test Positivity in B-Chronic Lymphoid Leukemia: a Marker of Advanced Clinical Disease.

BACKGROUND: Chronic lymphoid leukemia (CLL) is a malignant hematopoietic disorder, the most common of all adult leukemias with a distinctive immunophenotype. It is well established that CLL patients can have autoimmune complications, amongst them autoimmune hemolytic anemia as the most frequent. This study was carried out to determine the frequency of direct Coombs Test positivity in CLL patients and its possible correlation with Rai staging, hematological parameters and biochemical markers. MATERIALS AND METHODS: This descriptive cross sectional study was carried at Liaquat National Hospital from January 2011 to June 2013. Sixty untreated patients with B- chronic lymphoid leukemia were enrolled. Complete blood count, direct Coombs test, serum urea, creatinine, uric acid and LDH levels were determined. Data were compiled and analyzed using SPSS version 21. RESULTS: Out of 60 patients, 42(70%) were males and 18(30%) were females. Mean age was 59±9.2 years. Male to female ratio was 2.1: 1. The frequency of direct antiglobulin test (DAT) positivity was found to be 23.3%. The monospecific IgG was positive in 11 patients (18.3%); C3d positivity was evident in 1 patient (1.6%) and 2 patients (3.3%) had dual IgG and C3d positivity. The mean hemoglobin was 10.8±2.4gm/ dl. Significantly low mean hemoglobin of 8.3±3.0 gm/dl was seen in Coombs positive patients compared with negative patients having a mean hemoglobin level of 11.7±1.6 gm/dl (P<0.001). DAT positivity also demonstrated a positive association with advanced Rai stage III disease (P<0.01). No associations were noted with age, gender and biochemical markers. CONCLUSIONS: Direct Coombs test positivity in CLL in our patients, unlike in Western studies, appears relatively high, indicating significant autoimmune hemolytic anemia and advanced Rai stage in our setting. DAT positivity can be considered as a surrogative marker for advanced clinical disease.

Coombs negative autoimmune hemolytic anemia in Crohn's disease.

BACKGROUND: Anemia is a common, important extraintestinal complication of Crohn's disease. The main types of anemia in patients with Crohn's disease are iron deficiency anemia and anemia of chronic disease. Although patients with Crohn's disease may experience various type of anemia, autoimmune hemolytic anemia (AIHA) in patients with Crohn's disease, especially Coombs-negative AIHA, is very rare. CASE REPORT: A 41-year-old woman with Crohn's disease presented to our emergency room (ER) with dark urine, dizziness, and shortness of breath. The activity of Crohn's disease had been controlled, with Crohn's disease activity index (CDAI) score below 100 point. On physical examination, the patient had pale conjunctivae and mildly icteric sclerae. Serum bilirubin was raised at 3.1 mg/dL, lactate dehydrogenase (LDH) level was 1418 U/L and the haptoglobin level was <3 mg/dL. Results of direct and the indirect Coombs tests were all negative. We then measured the RBC-IgG to evaluate the possibility of Coombs-negative AIHA. The result revealed that RBC-IgG level was 352 IgG molecules/cell, with the cut-off value at 78.5 IgG molecules/cell. CONCLUSIONS: We report a case of Coombs-negative AIHA in a patient with Crohn's disease with chronic anemia, diagnosed by red blood cell-bound immunoglobulin G (RBC-IgG) and treated with steroids therapy.

Primary Sjögren syndrome presenting with hemolytic anemia and pure red cell aplasia following delivery due to Coombs-negative autoimmune hemolytic anemia and hemophagocytosis.

A 36-year-old woman presented with hemolytic anemia without a reticulocyte response 38 days after delivery. A marked reduction in erythroid cells and an increase in macrophages with active hemophagocytosis were noted in the bone marrow. While conventional Coombs' tests were negative, the level of red blood cell (RBC)-bound immunoglobulin G (IgG) was increased. The patient was diagnosed with primary Sjögren syndrome (pSS) based on her symptoms, positive anti-SS-A antibodies, Coombs-negative autoimmune hemolytic anemia and pure red cell aplasia associated with RBC-bound IgG and hemophagocytosis. The unique presentation was considered to be a consequence of immunological derangement associated with pSS, pregnancy and delivery.

Should a positive direct antiglobulin test be considered a prognostic predictor in chronic lymphocytic leukemia?

BACKGROUND: The clinical course of patients with B-cell CLL is often complicated by autoimmune phenomena. The DAT might be positive at some time during the course of the disease in up to 35% of cases. The aim of this retrospective study was to investigate the relationship between the occurrence of a positive DAT and biological features of CLL patients. PATIENTS AND METHODS: In our institution, 146 untreated patients with CLL were studied using the DAT. RESULTS: According to the statistical analysis, a high level of ß2-microglobulin and unmutated IgHV emerged as factors significantly related to the presence of DAT positivity. Time to first TFS was significantly shorter in DAT-positive patients. The adverse effect of a DAT positive result was maintained in terms of TFS when patients with mutated IgHV status were excluded from statistical analysis. CONCLUSION: These results suggest that the DAT might provide additional prognostic information regarding patients with IgHV unmutated status.

Invasive pneumococcal pneumonia is the major cause of paediatric haemolytic-uraemic syndrome in Taiwan.

AIM: Streptococcus pneumoniae-associated haemolytic uraemic syndrome (SP-HUS) is a major concern of paediatric acute renal failure in Taiwan; it leads to significant morbidity and mortality during the acute phase and to long-term morbidity after an acute episode. METHODS: Twenty children diagnosed with HUS between 1 May 1995, and 31 December 2008 was enrolled. Clinical variables related to laboratory data, organ involved, and outcomes were examined between patients with and without SP-HUS. RESULTS: Thirteen of the 20 (13/20, 65%) patients required dialysis, nine (9/20, 45.0%) developed hepatic dysfunction, disseminated intravascular coagulation (DIC), gastrointestinal bleeding, and hypertension, respectively. They were the second most common extrarenal complication except empyema (11/20, 55%). Two (10%) died and seven (35%) of the survivors developed long-term renal morbidity. Twelve of the 20 patients (60%) were diagnosed with SP-HUS. Younger age, female children, higher white blood cell count, higher alanine transaminase, higher lactate dehydrogenase and high incidence of DIC were significantly common in SP-HUS cases. All SP-HUS cases were complicated with pleural effusion, empyema, or both. Positive Thomsen-Freidenreich antigen (T-Ag) activation was 83% sensitive and 100% specific for SP-HUS, and a positive direct Coombs' test was 58% sensitive and 100% specific. CONCLUSION: Invasive pneumococcal infection is the most common cause of HUS in Taiwan. Positive T-Ag activation and a direct Coombs' test are rapid predictors of SP-HUS in children with invasive pneumonia.