Nephrotic-range proteinuria and central nervous involvement in typical hemolytic uremic syndrome: a case report.

BACKGROUND: Hemolytic uremic syndrome (HUS), a common subtype of thrombotic microangiopathy (TMA), is characterized by microangiopathic hemolytic anemia, thrombocytopenia, and acute kidney injury. Shiga toxin-producing Escherichia coli infection is the most common cause of post-diarrheal HUS. Kidney and central nervous system are the primary target organs. CASE PRESENTATION: A 64-year-old male presented with HUS following bloody diarrhea. Nephrotic-range proteinuria and hypoalbuminemia were present at the acute stage and renal histology revealed common TMA features. Neurological involvement presented as confusion and impaired cognitive function. Cranial magnetic resonance imaging demonstrated bilateral T2 hyperintensities in the brainstem and insula. The patient received plasma exchange and supportive care. Both the renal and neurological impairments were completely recovered 3 months after the onset. CONCLUSION: We report an adult patient presenting with nephrotic-range proteinuria and central nervous system involvement at the acute phase of post-diarrheal HUS. The reversibility of the organ damages might predict a favorable outcome.

Ockham's razor defeated: about two atypical cases of hemolytic uremic syndrome.

BACKGROUND: Medical investigation is a favorite application of Ockham's razor, in virtue of which when presented with competing hypotheses, the solution with the fewest assumptions should be privileged. Hemolytic uremic syndrome (HUS) encompasses diseases with distinct pathological mechanisms, such as HUS due to shiga-like toxin-producing bacteria (STEC-HUS) and atypical HUS, linked to defects in the alternate complement pathway. Other etiologies such as Parvovirus B19 infection are exceptional. All these causes are rare to such extent that we usually consider them mutually exclusive. We report here two cases of HUS that could be traced to multiple causes. CASES PRESENTATION: Case 1 presented as vomiting and diarrhea. All biological characteristics of HUS were present. STEC was found in stool (by PCR and culture). After initial remission, a recurrence occurred and patient was started on Eculizumab. Genetic analysis revealed the heterozygous presence of a CFHR1/CFH hybrid gene. The issue was favorable under treatment. In case 2, HUS presented as fever, vomiting and purpura of the lower limbs. Skin lesions and erythroblastopenia led to suspect Parvovirus B19 primo-infection, which was confirmed by peripheral blood and medullar PCR. Concurrently, stool culture and PCR revealed the presence of STEC. Evolution showed spontaneous recovery. CONCLUSIONS: Both cases defy Ockham's razor in the sense that multiple causes could be traced to a single outcome; furthermore, they invite us to reflect on the physiopathology of HUS as they question the classical distinction between STEC-HUS and atypical HUS. We propose a two-hit mechanism model leading to HUS. Indeed, in case 1, HUS unfolded as a result of the synergistic interaction between an infectious trigger and a genetic predisposition. In case 2 however, it is the simultaneous occurrence of two infectious triggers that led to HUS. In dissent from Ockham's razor, an exceptional disease such as HUS may stem from the sequential occurrence or co-occurrence of several rare conditions.

New insights into the pathogenesis of Streptococcus pneumoniae-associated hemolytic uremic syndrome.

The purpose of this review is to describe Streptococcus pneumoniae-associated hemolytic uremic syndrome (P-HUS) with emphasis on new insights into the pathophysiology and management over the past 10 years. Even though awareness of this clinico-pathological entity has increased, it likely remains under-recognized. Recent observations indicate that although neuraminidase activity and exposure of the T-antigen are necessary for development of P-HUS, they are not sufficient; activation of the alternate pathway of complement may also contribute. It is unclear, however, whether or not eculizumab and/or plasmapheresis are of value.

Extrarenal manifestations of the hemolytic uremic syndrome associated with Shiga toxin-producing Escherichia coli (STEC HUS).

Hemolytic uremic syndrome is commonly caused by Shiga toxin-producing Escherichia coli (STEC). Up to 15% of individuals with STEC-associated hemorrhagic diarrhea develop hemolytic uremic syndrome (STEC HUS). Hemolytic uremic syndrome (HUS) is a disorder comprising of thrombocytopenia, microangiopathic hemolytic anemia, and acute kidney injury. The kidney is the most commonly affected organ and approximately half of the affected patients require dialysis. Other organ systems can also be affected including the central nervous system and the gastrointestinal, cardiac, and musculoskeletal systems. Neurological complications include altered mental status, seizures, stroke, and coma. Gastrointestinal manifestations may present as hemorrhagic colitis, bowel ischemia/necrosis, and perforation. Pancreatitis and pancreatic beta cell dysfunction resulting in both acute and chronic insulin dependant diabetes mellitus can occur. Thrombotic microangiopathy (TMA) in cardiac microvasculature and troponin elevation has been reported, and musculoskeletal involvement manifesting as rhabdomyolysis has also been described. Extrarenal complications occur not only in the acute setting but may also be seen well after recovery from the acute phase of HUS. This review will focus on the extrarenal complications of STEC HUS. To date, management remains mainly supportive, and while there is no specific therapy for STEC HUS, supportive therapy has significantly reduced the mortality rate.

Síndrome hemolítico urémico: estado actual / Where are we with haemolytic uremic syndrome?

El síndrome hemolítico urémico (SHU) se caracteriza por una anemia hemolítica microangiopática con deterioro de función renal. Actualmente se clasifica en SHU asociado a toxina Shiga y SHU atípico, y el mecanismo común consiste en un daño grave del endotelio vascular que origina una microangiopatía trombótica. Dentro del SHU atípico se engloban formas primarias, secundarias y debidas a enfermedades metabólicas. En la gran mayoría de casos de SHU atípico, la hiperactividad de la vía alternativa del complemento juega un papel patogénico central. El tratamiento se basa en el bloqueo de la formación del complejo de ataque de membrana, molécula final de la vía alternativa del complemento, con eculizumab, que ha revolucionado la historia natural de la enfermedad. La recidiva de la enfermedad en el trasplante es frecuente y con muy mal pronóstico para la supervivencia renal

Haemolytic uremic syndrome (HUS) is characterised by microangiopathic haemolytic anaemia with acute kidney injury. It is currently classified into two main categories: Shiga-toxin producing E. coli-hemolytic uremic syndrome (STEC-HUS) and atypical haemolytic uremic syndrome (aHUS). Endothelial cell damage is the common pathway in HUS to developing thrombotic microangiopathy. Atypical HUS includes primary, secondary and aHUS due to metabolic diseases. In the majority of aHUS cases, hyperactivity of the alternative complement pathway plays a central role. Therefore, treatment is based on complement inhibitors like eculizumab, a drug that has revolutionised the natural history of the disease. Relapses are frequent after kidney transplant and thus confer a poor prognosis

HELLP Syndrome: Pathophysiology and Current Therapies.

HELLP syndrome is a disorder associated with serious maternal morbidity and mortality. Distinguishing HELLP from other pregnancy-related disorders is often challenging and may result in delay of treatment. Differential diagnoses include acute fatty liver of pregnancy, thrombotic thrombocytopenic purpura, antiphospholipid syndrome, and hemolytic uremic syndrome, and are reviewed in this chapter. While there is not any current treatment for HELLP, the mainstay of treatment involves maternal stabilization and timely delivery. Various treatment strategies have been attempted to help decrease the morbidity and mortality of HELLP, including the maternal use of corticosteroids. The authors review the studies and controversies surrounding the maternal use of corticosteroids, plasma exchange, and low molecular weight heparin for the treatment of HELLP, as well as the role of the complement system in HELLP. Further large, well-designed, randomized controlled trials are needed to address the role corticosteroids may play in the treatment of women with HELLP and to help improve maternal and fetal outcomes.

Experimental In Vivo Models of Bacterial Shiga Toxin-Associated Hemolytic Uremic Syndrome.

Shiga toxins (Stxs) are the main virulence factors expressed by the pathogenic Stx-producing bacteria, namely, Shigella dysenteriae serotype 1 and certain Escherichia coli strains. These bacteria cause widespread outbreaks of bloody diarrhea (hemorrhagic colitis) that in severe cases can progress to life-threatening systemic complications, including hemolytic uremic syndrome (HUS) characterized by the acute onset of microangiopathic hemolytic anemia and kidney dysfunction. Shiga toxicosis has a distinct pathogenesis and animal models of Stx-associated HUS have allowed us to investigate this. Since these models will also be useful for developing effective countermeasures to Stx-associated HUS, it is important to have clinically relevant animal models of this disease. Multiple studies over the last few decades have shown that mice injected with purified Stxs develop some of the pathophysiological features seen in HUS patients infected with the Stx-producing bacteria. These features are also efficiently recapitulated in a non-human primate model (baboons). In addition, rats, calves, chicks, piglets, and rabbits have been used as models to study symptoms of HUS that are characteristic of each animal. These models have been very useful for testing hypotheses about how Stx induces HUS and its neurological sequelae. In this review, we describe in detail the current knowledge about the most well-studied in vivo models of Stx-induced HUS; namely, those in mice, piglets, non-human primates, and rabbits. The aim of this review is to show how each human clinical outcome-mimicking animal model can serve as an experimental tool to promote our understanding of Stx-induced pathogenesis.

Haemolytic-uremic syndrome due to infection with adenovirus: A case report and literature review.

RATIONALE: Haemolytic-uremic syndrome is a rare but serious complication of bacterial and viral infections, which is characterized by the triad of: acute renal failure, microangiopathic haemolytic anemia and thrombocytopenia, sometimes severe, requiring peritoneal dialysis. In Europe, hemolytic-uremic syndrome (HUS) in paediatric pathology is primarily caused by Shiga toxin-producing Escherichia coli (STEC) O157, followed by O26. Beside these etiologies, there are other bacterial and viral infections, and also noninfectious ones that have been associated to lead to HUS as well: in the progression of neoplasia, medication-related, post-transplantation, during pregnancy or associated with the antiphospholipid syndrome, systemic lupus erythematosus or family causes with autosomal dominant or recessive inheritance. In terms of pathogenesis, HUS is the result of endothelial injury, most commonly being a result of the action of Shiga toxin. The unfavorable prognosis factors being represented by the age of more than 5 years old, different etiologies from STEC, persistent oligoanuria, central nervous system and glomerular impairment, the association of fever with leukocytosis. HUS is responsible for 7% of cases of hypertension in infants, and an important cause of significant kidney damage in adults. PATIENT CONCERNS: We present one case of HUS caused by adenovirus in a boy of 1 year and 7 months old with severe evolution, which required peritoneal dialysis. DIAGNOSE: Stool sample repeated examination for adenovirus antigen was positive in 2 samples. INTERVENTION: During hospitalization, the patient required 8 peritoneal dialysis sessions. OUTCOME: The renal function was corrected on discharge, the patient required cardiovascular monitoring 1 month after discharge. LESSON: Although the most common cause that leads to HUS remains STEC, other etiologies like viral ones that may be responsible for severe enteric infection with progression into HUS should not be neglected.

Pathophysiology of thrombotic thrombocytopenic purpura and hemolytic uremic syndrome.

Thrombotic microangiopathies are rare disorders characterized by the concomitant occurrence of severe thrombocytopenia, microangiopathic hemolytic anemia, and a variable degree of ischemic end-organ damage. The latter particularly affects the brain, the heart, and the kidneys. The primary forms, thrombotic thrombocytopenic purpura (TTP) and hemolytic uremic syndrome (HUS), although their clinical presentations often overlap, have distinctive pathophysiologies. TTP is the consequence of a severe ADAMTS-13 deficiency, either immune-mediated as a result of circulating autoantibodies, or caused by mutations in ADAMTS-13. HUS develops following an infection with Shiga-toxin producing bacteria, or as the result of excessive activation of the alternative pathway of the complement system because of mutations in genes encoding complement system proteins.

Treatment of Acute Kidney Injury in Hemolythic Uremic Syndrome (TTP).

INTRODUCTION: Plasmapheresis is often used as a therapy in the treatment of thrombotic thrombocytopenic purpura (TTP). TTP is manifested in thrombotic microangiopathy, consumed thrombocytopenia, hemolytic anemia and acute kidney injury with HUS development, neurologic dysfunction, and fever. CASE REPORT: we will present a case of a patient with acute kidney injury and refractory TTP at the beginning of hospitalization, subsequently manifested in secondary nephrotic syndrome. The patient was a female, 39 years of age, who as an emergency case was referred from the hospital in East Sarajevo to the Clinic of Endocrinology, Diabetes and Metabolism Disorders of the Clinical Center University of Sarajevo with suspected TTP. A few days before hospitalization she had a fever and vomiting, and therefore consulted her physician. She was hospitalized due to severe general condition, generalized edema, visible body hematomas, and diuresis amounting to 600 ml/12 hours. Laboratory results on admission were as follows: Leukocytes 19.5, Erythrocytes 3.23, Hemoglobin 103, Hematocrit 28.8%, Platelets 65.4 with few schistocytes and 2 reticulocytes, Sodium 140 mmol/L,, Potassium 4.5 mmol/L, Calcium 1.90 mmol/L, Glucose 7.9 mmol/L, Urea 37.5 mmol/L, Creatinine 366 umol/L,, Bilirubin 19.0 umol/L, Lactate dehydrogenase 1194 U /L. The patient was communicative, in cardiopulmonary sufficient state. Central venous catheter was placed in the right jugular vein and the first plasmapheresis was performed. During the hospitalization 38 plasmapheresis treatments with frozen plasma were performed, followed by three Rituximab treatment cycles. After the last plasmapheresis treatment a platelet count was 138. Also, parameters of the renal function were in their referent values. At the beginning of the treatment proteinuria was 19.6 g/24 hours urine. We were faced with a dilemma whether renal biopsy should be repeated in the future given that it might be the case of primary and not secondary nephrotic syndrome. Controlled proteinuria was 4.7g after plasmapheresis. The patient used only Prednisolone at a dose of 10 mg daily and although initially diagnosed with acute kidney injury she was not treated with dialysis. CONCLUSION: early diagnosis and early start of plasmapheresis therapy is vital for treatment of patients with acute kidney injury and TTP (HUS). A small number of patients is refractory to plasmapheresis and introducing Rituximab and plasmapheresis treatment is recommended.

Syndromes of Thrombotic Microangiopathy.

Thrombotic thrombocytopenia purpura (TTP) and the hemolytic uremic syndrome (HUS) are rare thrombotic microangiopathies that can be rapidly fatal. Although the acquired versions of TTP and HUS are generally highest on this broad differential, multiple rarer entities can produce a clinical picture similar to TTP/HUS, including microangiopathic hemolysis, renal failure, and neurologic compromise. More recent analysis has discovered a host of genetic factors that can produce microangiopathic hemolytic syndromes. This article discusses the current understanding of thrombotic microangiopathy and outlines the pathophysiology and causative agents associated with each distinct syndrome as well as the most accepted treatments.

Clinical characteristics and long-term outcome of diarrhea-associated hemolytic uremic syndrome: a single center experience.

OBJECTIVES: To clarify the clinical characteristics and long-term outcomes of patients with diarrhea-associated hemolytic uremic syndrome (D + HUS) with a particular focus on time course. METHODS: We retrospectively analyzed the medical records of 61 patients with D + HUS who were admitted to Kobe University Hospital between 1995 and 2015. The onset of D + HUS was defined as day 1 of diarrhea. RESULTS: The age of onset was 4.1 (1.5-13.4) years, and the period between onset and diagnosis of D + HUS was 5 (3-18) days. The platelet count was lowest on day 7 (4-24), and the lactase dehydrogenase level was maximal on day 8 (4-25). Twenty-three patients required dialysis for 13 (2-37) days, starting at day 5-9. Seventeen patients showed central nervous system (CNS) symptoms at day 4-18. They were followed up for 3.7 (0-18.4) years. At the final follow-up, estimated glomerular filtration rate was 113.7 (57.9-159.9) ml/min/1.73 m2 with five patients having chronic kidney disease. Three patients developed CNS sequelae. The time to diagnosis was significantly shorter in the group of patients receiving dialysis than without dialysis (p = 0.018) and in the group with CNS complications than without (p = 0.013). CONCLUSION: CNS complications were often apparent after blood examination results improved. Moreover, a shorter period between the onset of diarrhea and a diagnosis of D + HUS indicated a more severe clinical course or long-term sequelae, and it should be considered as a risk factor for poor prognosis.

The clinical and laboratory features of Chinese Han anti-factor H autoantibody-associated hemolytic uremic syndrome.

BACKGROUND: Anti-complement factor H (CFH) autoantibody-associated hemolytic uremic syndrome (HUS) is a severe sub-type of HUS. METHODS: We assessed the clinical and renal pathological features, circulating complement levels, and genetic background of Chinese pediatric patients with this sub-type of HUS. Thirty-three consecutive patients with acute kidney injury who tested positive for serum anti-CFH autoantibodies were enrolled in this study. RESULTS: All of the eight patients who underwent renal biopsies presented with changes typical of thrombotic microangiopathy, especially changes in chronic characteristics. Compared to patients in remission and normal control subjects, patients with acute disease had significantly lower plasma CFH levels and significantly higher plasma complement 3a (C3a), C5a, and terminal complement complex (SC5b-9) levels. The CFH-anti-CFH immunoglobin G (IgG) circulating immunocomplex (CFH-CIC) titers were more closely correlated with CFH plasma levels than anti-CFH IgG levels. Of the 22 patients, four (18%) were homozygous for CFHR3-1Δ and ten were heterozygous for CFHR1 or CFHR3 deletions. Most patients responded well to a combination of plasma and immunosuppressive therapies, with a remission rate of 87%. At the end of the follow-up, nine patients reached the combined end-points, including two with end-stage renal disease and seven with relapses. CONCLUSION: Plasma C3a, C5a, and SC5b-9 levels predicted disease activity in anti-CFH autoantibody-associated HUS patients enrolled in this study. These patients responded well to plasma therapy combined with immunosuppression.

Renal thrombotic microangiopathy in patients with cblC defect: review of an under-recognized entity.

Methylmalonic aciduria and homocystinuria, cobalamin C (cblC) type, is the most common genetic type of functional cobalamin (vitamin B12) deficiency. This metabolic disease is characterized by marked heterogeneity of neurocognitive disease (microcephaly, seizures, developmental delay, ataxia, hypotonia) and variable extracentral nervous system involvement (failure to thrive, cardiovascular, renal, ocular) manifesting predominantly early in life, sometimes during gestation. To enhance awareness and understanding of renal disease associated with cblC defect, we studied biochemical, genetic, clinical, and histopathological data from 36 patients. Consistent clinical chemistry features of renal disease were intravascular hemolysis, hematuria, and proteinuria in all patients, with nephrotic-range proteinuria observed in three. Renal function ranged from normal to renal failure, with eight patients requiring (intermittent) dialysis. Two thirds were diagnosed with atypical (diarrhea-negative) hemolytic uremic syndrome (HUS). Renal histopathology analyses of biopsy samples from 16 patients revealed glomerular lesions typical of thrombotic microangiopathy (TMA). Treatment with hydroxycobalamin improved renal function in the majority, including three in whom dialysis could be withdrawn. Neurological sequelae were observed in 44 % and cardiopulmonary involvement in 39 % of patients, with half of the latter group demonstrating pulmonary hypertension. Mortality reached 100 % in untreated patients and 79 and 56 % in those with cardiopulmonary or neurological involvement, respectively. In all patients presenting with unclear intravascular hemolysis, hematuria, and proteinuria, cblC defect should be ruled out by determination of blood/plasma homocysteine levels and/or genetic testing, irrespective of actual renal function and neurological status, to ensure timely diagnosis and treatment.

Haemolytic uraemic syndrome.

Haemolytic uraemic syndrome (HUS) is defined by the simultaneous occurrence of nonimmune haemolytic anaemia, thrombocytopenia and acute renal failure. This leads to the pathological lesion termed thrombotic microangiopathy, which mainly affects the kidney, as well as other organs. HUS is associated with endothelial cell injury and platelet activation, although the underlying cause may differ. Most cases of HUS are associated with gastrointestinal infection with Shiga toxin-producing enterohaemorrhagic Escherichia coli (EHEC) strains. Atypical HUS (aHUS) is associated with complement dysregulation due to mutations or autoantibodies. In this review, we will describe the causes of HUS. In addition, we will review the clinical, pathological, haematological and biochemical features, epidemiology and pathogenetic mechanisms as well as the biochemical, microbiological, immunological and genetic investigations leading to diagnosis. Understanding the underlying mechanisms of the different subtypes of HUS enables tailoring of appropriate treatment and management. To date, there is no specific treatment for EHEC-associated HUS but patients benefit from supportive care, whereas patients with aHUS are effectively treated with anti-C5 antibody to prevent recurrences, both before and after renal transplantation.

[Pregnancy-related acute kidney injury].

Acute kidney injury (AKI) in obstetrics may be caused by the same disorders that are observed in the general population or may be specific for a pregnancy such as: preeclampsia, HELLP syndrome or acute fatty liver of pregnancy. The renal changes may be only temporary, and resolve within a few weeks postpartum, or may become irreversible leading to a progression of chronic kidney disease (CKD). In the article the most important pregnancy related syndromes associated with AKI have been shortly reviewed.

Hemolytic uremic syndrome in children.

Hemolytic uremic syndrome (HUS) is a thrombotic microangiopathy defined by thrombocytopenia, non-immune microangiopathic hemolytic anemia and acute renal failure. HUS is typically classified into two primary types: 1) HUS due to infections, often associated with diarrhea (D+HUS, Shiga toxin-producing Escherichia Coli-HUS), with the rare exception of HUS due to a severe disseminated infection caused by Streptococcus; 2) HUS related to complement, such HUS is also known as "atypical HUS" and is not diarrhea associated (D-HUS, aHUS); but recent studies have shown other forms of HUS, that can occur in the course of systemic diseases or physiopathological conditions such as pregnancy, after transplantation or after drug assumption. Moreover, new studies have shown that the complement system is an important factor also in the typical HUS, in which the infection could highlight an underlying dysregulation of complement factors. Clinical signs and symptoms may overlap among the different forms of HUS. Shiga toxin-producing Escherichia Coli (STEC) infection cause a spectrum of clinical sings ranging from asymptomatic carriage to non-bloody diarrhea, hemorrhagic colitis, HUS and death. The average interval between ingestion of STEC and illness manifestation is approximately 3 days, although this can vary between 2 and 12 days. Patients with pneumococcal HUS usually have a severe clinical picture with microangiopathic hemolytic anemia, respiratory distress, neurological involvement. The atypical HUS, in contrast to STEC-HUS which tends to occur as a single event, is a chronic condition and involves a poorer prognosis. Early diagnosis and identification of underlying pathogenic mechanism allow instating specific support measures and therapies. Typical management of STEC-HUS patients relies on supportive care of electrolyte and water imbalance, anemia, hypertension and renal failure. For the aHUS the initial management is supportive and similar to the approach for STEC-HUS; currently we have moved from the historic plasma therapy to new therapeutic approaches, first of all eculizumab, a monoclonal antibody that blocks the C5 cascade. This drug has shown an improvement in platelet count, cessation of hemolysis, improvement of renal function within a few days after the treatment. In patients with end-stage renal disease (ESRD) renal transplantation from a non-related donor and prophylactic administration of eculizumab to prevent recurrent disease in the allograft could be considered.