tailieunhanh - Diseases of the Liver and Biliary System - part 2

Xét nghiệm chức năng gan cho kết quả bình thường. Trong những trường hợp nặng hemoglobin miễn phí được phát hiện trong máu và nước tiểu. Chẩn đoán khó khăn phát sinh khi một bệnh nhân bị một căn bệnh có thể phức tạp suy tế bào gan hoặc tắc nghẽn đường mật | 56 Chapter 4 Paroxysmal nocturnal haemoglobinuria 10 In this rare acquired disease there is intravascular complement-mediated haemolysis. The defect is due to mutation of the PIG-A gene on chromosome X which results in deficient biosynthesis of the glycosylphosphatidylinositol GPI anchor. This leads to an absence of certain proteins on the red cell surface. The cells are sensitive to lysis when the pH of the blood becomes more acid during sleep. During an episode of haemolysis the urine passed in the morning may be brown or reddish-brown due to haemoglobinuria. Acutely the patients show a dusky reddish jaundice and the liver enlarges. Aspartate transaminase may be increased due to haemolysis and serum studies show iron deficiency due to urinary loss of haemoglobin . Liver histology shows some centrizonal necrosis and siderosis. Hepatic vein thrombosis may be a complication. Bile duct changes similar to primary sclerosing cholangitis perhaps due to ischaemia have been reported 4 . Acquired haemolytic anaemia The haemolysis is due to extra-corpuscular causes. Spherocytosis is slight and osmotic fragility only mildly impaired. The patient is moderately jaundiced. The increased bilirubin is unconjugated but in severe cases conjugated bilirubin increases and appears in the urine. This may be related to bilirubin overload in the presence of liver damage. Blood transfusion accentuates the jaundice for transfused cells survive poorly. The haemolysis may be idiopathic. The increased haemolysis is then due to autoimmunization. The Coombs test is positive. The acquired type may complicate other diseases especially those involving the reticulo-endothelial system. These include Hodgkin s disease the leukaemias reticu-losarcoma carcinomatosis and uraemia. The anaemia of hepato-cellular jaundice is also partially haemolytic. The Coombs test is usually negative. Autoimmune haemolytic anaemia is a rare complication of autoimmune chronic hepatitis and primary biliary cirrhosis. .