Sindromehemolítico-urêmica Antonio Souto firstname.lastname@example.org Médico coordenador Unidade de Medicina Intensiva Pediátrica Unidade de Medicina Intensiva Neonatal Hospital Padre Albino Professor de Pediatria nível II Faculdades Integradas Padre Albino Catanduva / SP 2011
H emolytic uremic syndrome isthe most common cause of acuterenal failure in children,and the incidence of this syndrome inchildren is increasing worldwide.
Epidemiology•Primarily occurs in children one to 10 years of age•Annual incidence: 1-3/100,000•Survival rate of nearly 90 percent•Rural populations are more at risk•Incidence is higher in warmer months•Three to 15 percent of persons who have STEC withdiarrheaE. coli O157:H7 strains could survive for as long asone year Am Fam Physician 2006;74:991-6, 998.
EpidemiologyRisk factors:•Age•Bloody diarrhea•Fever•Elevated white blood cell count•Elevated C-reactive protein levels•The use of antibiotics or antimotility/antidiarrhealand antimicrobial agents Am Fam Physician 2006;74:991-6, 998.
EtiologyTwo types (diarrheal prodrome)•Diarrhea-positiveShiga toxin–producing EscherichiacoliE. coli O157:H7 other strains also have beenimplicatedDiarrhea-negative in adults can have a genetic causeand generally has a poor prognosis
EtiologyE. coli O157:H7 is believed to cause more than 80percent of the STEC infections that lead tohemolytic uremic syndrome.Form of transmission to children•ingestion of undercooked beef containing E. coli•by contact with persons who inadequately washtheir hands, resulting in fecal and oralcontamination and transmission
There is increasing awareness thatother organisms, drugs, and conditionscan also initiate the triad ofmicroangiopathic hemolytic anemia,thrombocytopenia, and acutenephropathy that defines HUS. Current Opinion in Pediatrics 2005, 17:200–204
. Distribution of hemolytic uremic syndrome cases associated with Shiga toxin–producingEscherichia coli O157, 026, O111, and O145, by year
Shiga ToxinToxin is almost identical to Stx from ShigelladysenteriaeStx cause different degrees and types of tissuedamageHigher pathogenicity of strains that produce onlyStx-2, most commonly associated with HUS
•Oral ingestion• Stx-E. coli reaches the gut and closely adheres tothe epithelial cells• Stx then translocate into the circulation•Transport of Stx from the intestine to the kidney,consistently, Stx bound to circulating PMN•In vitro, PMN loaded with Stx transfer the ligand toglomerular endothelial cells
•The findings indicate that Stx favor leukocyte-dependent inflammation.•Activates endothelial cells that leads tomicrovascular thrombosis.•In vivo evidence of coagulation disturbances hasbeen found in children who developed HUS upon E.coli O157:H7 infection.•Recent work indicating that fibrinolysis issubstantially inhibited.
Clinical CharacteristicsThe classic triad:•Microangiopathic hemolytic anemia•Thrombocytopenia•Acute renal failureTypical hemolytic uremic syndrome usually developsafter a prodrome of diarrhea.
Clinical Characteristics•Clinical features are vague and may mimic commongastroenteritis•Bloody diarrhea three days to more than twoweeks before HUS•Additional symptoms: •Nonbloody diarrhea, abdominal cramping and nausea or vomiting. •Fever low grade or absent. •Ten percent of cases rectal prolapse with colitis
HUS cannot be diagnosedwithout evidence of hemolyticanemia.Hematologic findings: •Destruction and fragmentation of erythrocytes •Microangiopathic hemolytic anemia •92% develop thrombocytopenia •Clotting times are normal •Petechiae and purpura are uncommon
Schistocytes are fragmented red blood cells,and indicate mechanical damage causinghemolysis.
Acute renal failureWhen microthrombi are deposited in kidneyparenchyma•Hypertension•Oliguria and anuria•Edema
Microvascular•Vessel wall thickening•Endothelial swelling•Accumulation of proteins and cell debris in thesubendothelial layer
Microvascular•`The lesion is mainly confined to the glomerular tuftand is noted in an early phase of the disease.•Biopsies showed that most glomeruli are normal,whereas 15 to 20% eventually became sclerotic.
ManagementIs There Any Effective Treatment forStx-HUS?There is no treatment of provenvalue, and care during the acutephase of the illness is still merelysupportive
ManagementHUS is a selflimiting disease•Close monitoring and treatment of symptoms areessential•Wide spectrum of presentations•Supportive therapy•Close monitoring of fluid and electrolyte statusThe amount of parenteral hydration before thedevelopment of HUS, is crucial in preventing anuriaand, ultimately, dialysis.
ManagementDetecting early renal failure•Should be handled aggressively•Renal replacement therapy (peritoneal dialysis)•Hypertension is treated traditionallyAntibiotics and antimotility agents are notrecommended as treatments for hemolytic uremicsyndrome during the diarrheal stage of the disease.
ManagementStudies of antibiotic usage in children with E. coliO157:H7 infections show an increased risk ofcomplications from HUS
ManagementOn the basis of available data, wesuggest that in patients with Stx-E.coli gastrointestinal infection,antibiotics should be avoided unlessin cases with sepsis.
ManagementSerial monitoring of the hematocrit and plateletcount is important •Platelet transfusion can worsen the thrombotic process •Transfusion of red blood cells may be needed •Transfusion can deteriorate the patient’s condition
ManagementRenin-angiotensin system blockade may beparticularly beneficial•Early restriction of proteins and use of angiotensin-converting enzyme inhibitors may have a beneficialeffect•Treatment with angiotensin-converting enzymeinhibitors normalized BP, reduced proteinuria, andimproved GFR.