Hemolytic syndrome - Hyperuremia

Article written by Doctor of Emergency Department - Vinmec Phu Quoc International General Hospital

Hemolytic uremic syndrome is a group of rare diseases, characterized by hemolytic anemia, thrombocytopenic purpura, renal failure of varying degrees, and nervous system damage. , microvascular disease.

+ Intestinal infections: The intestinal bacteria causing hemolytic uremic syndrome are Escherichia Coli, sero type 0157:H7. Other bacteria that may also be encountered include Shigella, Salmonella and a number of other nonspecific enteric bacteria.
+ Primary: hemolytic-uremic syndrome can occur primary, with no known cause.
+ Combination: hemolytic-uremic syndrome can occur in combination with certain other conditions or diseases.

Hemolytic-uremic syndrome is also known as thrombotic microvascular disease, because of thrombus formation of platelets and fibrin in small arteries and arterioles. This lesion plays a central role in the clinical presentation of this syndrome. Platelets and red blood cells are destroyed causing thrombocytopenia and anemia. The pathogenesis of hemolytic-uremic syndrome is not fully understood. Three main theories have been proposed, each explaining the unique condition of certain patients.
+ The first theory: This theory assumes that due to increased platelet agglutination agents in the blood. This phenomenon occurs at least in some cases. Several other substances may act as agglutinators, which may vary from patient to patient.
+ The second theory: This theory is attributed to a decrease in platelet agglutination inhibitors in the circulation. This phenomenon causes the formation of platelet thrombus, sometimes patients recover after plasma transfusion. This abnormality is caused by IgG deficiency in some patients.
+ The third theory: This theory suggests that platelet activation in this syndrome may be a secondary response to damage to endothelial cells. It has been shown that endothelial cell damage can cause hemolytic-uremic syndrome in some patients.

Hemolytic uremic syndrome can be clinical. The forms differ in clinical presentation, but they have much in common. For example, the histopathological changes of the trunk are similar. Patients with acute illness have thrombosis of platelets and fibrin in the small arteries, arterioles, and glomerular capillaries. Patients with acute or chronic disease have lesions in the arteries in the glomerulus. Lesions characterized by onion-like wall thickening are similar to those seen in scleroderma or malignant hypertension.

+ Thrombotic thrombocytopenic purpura (thrombotic thrombcytopenic purpura) is common in women aged 10-50 years. Characteristic symptoms are fever, thrombocytopenia (often associated with purpura), neurological abnormalities, hemolytic anemia, microvascular disease, and renal failure. The onset of the disease is often a flu-like syndrome, progressing to the appearance of purpura, neurological symptoms, and renal failure.
+ Child form: Hemolytic uremic syndrome in children, typically begins after a period of intestinal infection or viral infection. Often vomiting, severe diarrhea, toxicosis caused by Escherichia coli (especially sero type 01:H7) released or toxins from other bacteria. Renal failure is more severe than thrombocytopenic purpura. Anuria occurs in 50% of patients, and hypertension is also common.
+ Adult form: Hemolytic-uremic syndrome in adults is usually primary. Although some cases have been associated with certain other conditions or conditions, such as pregnancy especially in the third trimester, lupus, oral contraceptives containing estrogen, cancer of the lining of the digestive tract, cancer pancreatic cancer, prostate cancer, chemotherapy with mitomycin or in combination with Bleomycin and cyplatin, oral cyclosporin. The stage of gastroenteritis is similar to the pediatric type, which can occur but is uncommon.
The above three types may interfere both etiologically and clinically.

+ Early symptoms: Fever, vomiting and diarrhea, often severe diarrhea. The nervous state is easily excitable, weak, indifferent to the external environment.
+ Late symptoms: Oliguria, anuria, pale skin due to anemia, purpura as plaque or punctate due to thrombocytopenia. Yellow skin and mucous membranes due to hemolysis, impaired consciousness and possibly coma. Examination revealed enlarged liver, enlarged spleen, abnormal symptoms of the nervous system.

+ Subclinical
Hematology tests: decrease in platelet count, decrease in red blood cell count, increase in white blood cell count. Coagulation tests: The ratio of prothrombin, aPTT (activated partial thromboplastin time) is usually normal. Blood biochemical tests: The concentration of urea, blood creatinine increased, free hemoglobin increased. Urinalysis: in thrombocytopenic purpura, there may be red blood cells, red blood cell casts in the urine. Children and humans have normal urine tests, probably due to severe renal dysfunction combined with oliguria, anuria, which limits the excretion of cells in the urine. It should be noted that water analysis is nonspecific and is of no value to distinguishing bodies. Other tests: blood complement test normal, Stool test may be positive for E. Coli sero type 0157:H7. Renal biopsy: if acute disease shows thrombocytopenia and fibrin in the small arteries, arterioles and capillaries of the glomerulus, focal necrotizing glomerulonephritis. If the disease is subacute or chronic, there is damage to the arteries, scalloped arteriolar thickening resembles malignant hypertension or scleroderma. Renal histopathological lesions have prognostic significance. Predominant glomerular or renal artery involvement should be considered. In children with hemolytic-uremic syndrome, the glomeruli are damaged first and usually spontaneously recover. In contrast, in adults with hemolytic-uremic syndrome, the renal artery is usually affected first, although the glomeruli are also involved. Clinically, there is often severe hypertension and only a low rate of spontaneous recovery.

Diagnosis of hemolytic-uremic syndrome is based on clinical and laboratory findings. Distinction from disseminated intravascular coagulation syndrome is based on: hemolytic-uremic syndrome with thrombocytopenia, normal prothrombin and aPTT ratio. Complement levels in the blood were normal.

Hemolytic-uremic syndrome often causes severe complications in both children and adults, possibly fatal, especially in the presence of acute renal failure. The goal of treatment is to restore the platelet count. Restoration of platelet counts will respond to both ischemic necrosis caused by thrombocytopenia and bleeding caused by thrombocytopenia. About 60% of treated adult patients make a full recovery. Children have a better prognosis than adults.
+ Transfusion of red blood cells and platelets is necessary. However, there are two potential complications of platelet transfusion that should be emphasized. First, can cause acute renal failure due to extensive thrombosis when platelet transfusion. Second, it may lead to the emergence of new neurological symptoms or worsening of old neurological symptoms. The above two risks are due to the agents that cause platelet aggregation remain in the patient's blood.
+ Prednisolone high dose 2 mg/kg/day, used alone, can be effective for mild forms. However, if there is no increase in the platelet count after 48 hours, a plasma exchange should be considered. Antiplatelet agents such as aspirin, dipyridamole are not effective when used alone, but there may be some benefit when added to plasma exchange.
+ Plasma transfusion or plasma exchange is the most effective method. Plasma exchange with fresh or frozen plasma is more effective than plasma transfusion alone. The benefit of plasma exchange is that it eliminates the causative agent of platelet aggregation, and allows for the infusion of more frozen plasma than plasma transfusions and more than the amount of plasma removed. Plasma exchange should be performed daily until the platelet count returns to normal, and the hemolysis stops. This process requires an average of 7-8 plasma exchanges. Kidney function should return to normal or improve in about a week.
+ Extrarenal dialysis may be necessary in the presence of acute renal failure.

Most children with hemolytic-uremic syndrome after diarrhea recover completely clinically. Long-term often signs of chronic kidney damage, manifested by proteinuria, hypertension or renal failure. This manifestation occurs in about 30% of children with persistent illness, with anuria for more than one week or oliguria for more than two weeks. There are also children who do not recover from the acute phase, whose prognosis is poor when the disease does not improve within two weeks and the disease recurs.
Relapse is also common, most occurring within 30 days, but sometimes years later. Repeated plasma exchange therapy is often effective. Administration of vincristine and immunoglobulin infusion can also be successful in some cases.
Possible complications: hemolytic-uremic syndrome can become chronic or recurrent, acute renal failure, chronic renal failure.
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