Hepatitis B Vaccine-Associated Atypical Hemolytic Uremic Syndrome

Hemolytic uremic syndrome (HUS) is one of the common causes of acute renal failure in children and is characterized by microangiopathic hemolytic anemia and thrombocytopenia. About 5% to 10% of all HUS cases in children are non-diarrheal HUS (atypical HUS) [1,2]. Many triggering causes of atypical HUS, such as non-enteric infections, viruses, drugs, systemic diseases, glomerulopathies, malignancies, transplantations, and pregnancy, have been identified [1,2,3,4]. Here we report a patient who developed atypical HUS after a hepatitis B vaccination. A 55-day-old female infant was admitted to our hospital with sudden onset of jaundice and pallor 1 day after the second dose of recombinant hepatitis B vaccine injection (containing 10 µg HBsAg/0.5 mL and 0.475 mg aluminum hydroxide/0.5 mL). There was no history of fever, diarrhea, or cough. The first dose of hepatitis B vaccine was administered at birth. She had no health problems in the neonatal period and was solely breastfed. The family history was non-contributory. On physical examination, the patient was in poor general condition and hypoactive with pale and icteric skin. Body temperature was 37 °C, pulse rate was 140/min, respiratory rate was 48/min, and blood pressure was 70/40 mmHg. There was no hepatosplenomegaly. Laboratory examination revealed a hemoglobin level of 51 g/L, leukocyte count of 10x10 9 /L, platelet count of 28x10 9 /L, and reticulocyte level of 3.9%. Anisocytosis, poikilocytosis, polychromasia, helmet cells, marked schistocytes, and rare platelets were observed in the peripheral blood smear, compatible with microangiopathic hemolytic anemia and thrombocytopenia. Direct and indirect Coombs test results were negative. Biochemical analyses were as follows: urea 88 mg/dL (normal range: 5-18), creatinine 1.1 mg/dL (normal: 0.2-0.4), total bilirubin 13.7 mg/dL (normal: <1.2), direct bilirubin 2.6 mg/dL (normal: <0.2), uric acid 8.1 mg/ dL (normal: 2.4-6.4), aspartate aminotransferase 96 U/L (normal: 15-55), lactic dehydrogenase 4641 U/mL (normal: 170-580), and the other serum biochemical tests within normal limits. Urine microscopy showed numerous red blood cells. Microscopic examination of stool was normal and occult blood test results were negative. Her stool culture and urine culture were also negative. Serum complement component 3 (C3) and C4 levels were 76.5 mg/dL (normal: 79-752) and 5.89 mg/dL (normal: 16-38), respectively. Prothrombin time, activated partial thromboplastin time, and fibrinogen level were within the normal ranges. Renal ultrasound showed increased echogenicity in both kidneys. As the patient had acute renal failure, thrombocytopenia, and microangiopathic hemolytic anemia, she was diagnosed with HUS. After transfusion of red …