Drug-related immune hemolytic anemia

Introduction to drug-related immune hemolytic anemia Drug-induced hemolytic anemia is rare, and the drug can cause direct anti-human globulin test (DAT) positive and accelerate red blood cell destruction. Patients with hemolysis have a history of medication in the past, and may occur during long-term medication. Some patients have drug allergic reactions such as rash and fever before hemolysis. Hemolysis is usually subacute, mild, mainly extravascular. Relieve after a few days or weeks of withdrawal. basic knowledge The proportion of illness: 0.005% Susceptible people: no special people Mode of infection: non-infectious Complications: disseminated intravascular coagulation acute renal insufficiency

Drug-related immune hemolytic anemia

(1) Causes of the disease

Drugs are mainly found in penicillin, tetracycline, tolbutamide, phenacetin, sulfonamides, isoniazid, rifampicin, quinine and so on.

(two) pathogenesis

Drug-induced immune hemolytic anemia refers to the immune damage of red blood cells caused by certain drugs through immune mechanisms. According to the pathogenesis, drug-induced hemolytic anemia can be classified into three categories:

1 drug-induced immunity, resulting in antibody-mediated hemolysis;

2 drugs act on red blood cells with genetic enzyme defects;

3 The hemolytic reaction caused by abnormal hemoglobin, different mechanisms of autoimmune hemolytic anemia caused by different drugs, according to the principle of immunity can be divided into 4 types, namely hapten type, immune complex type, autoantibody type, non-immune type protein Adsorption type.

Hapten type

The representative drug is penicillin, which was first reported by Ley in 1959. So far, dozens of cases have been reported. The drug acts as a hapten with the erythrocyte membrane and the serum protein to form a whole antigen, and the antibody produced reacts with the drug adsorbed on the red blood cell, and further Injury destroys drug-bound red blood cells, but has no effect on normal red blood cells. It usually occurs in very large doses (12 million to 15 million U/d) or poor renal function, usually within 7 to 10 days after administration.

In addition to penicillin, cephalosporins can induce the same pathological changes because they can cross-react with penicillin antigen. In addition, tetracycline, tolbutamide, phenacetin and sulfonamides can also be used as haptens and membrane proteins. Combine.

2. Immune complex type

When the drug first contacts the body, it combines with serum proteins to form an antigen, which stimulates the body to produce antibodies. When the drug is repeatedly applied, the drug-antibody (immuno) complex is adsorbed on the erythrocyte membrane and activates complement, destroying red blood cells, and producing intravascular hemolysis. It is called immune complex type hemolytic anemia, and it belongs to more than 10 kinds of drugs of this type, but the incidence rate is not high, mainly including , isoniazid, rifampicin, quinine, quinidine , phenacetin, salicylic acid, sulfasalazine and insulin.

3. Autoantibody type

The antibody in serum can interact with the red blood cells, but it is not related to the presence or absence of the drug. The representative drug is methyldopa. Worlledge was first reported in 1966. The mechanism of action may be that the drug changes the protein of the Rh cell membrane of the erythrocyte membrane. An antibody that cross-reacts with the Rh protein.

In addition, the drugs causing such hemolytic anemia include levodopa, mefenamic acid (mexamic acid), procainamide, chlorpromazine and the like.

4. Non-immune protein adsorption type

About 5% of patients receiving cephalosporin have positive anti-human globulin test, often occurring 1 to 2 days after administration. Plasma proteins including immunoglobulin, complement, albumin, fibrinogen, etc. are on the erythrocyte membrane. Cases of non-specific adsorption, but no hemolysis, are strictly speaking, this type is not a drug-induced immunological hemolytic anemia.

Drug-related immune hemolytic anemia prevention

Patients with a history of drug allergy should be cautious when using penicillin, sulfa drugs, rifampicin, quinine, and phenacetin.

Drug-related immune hemolytic anemia complications Complications, disseminated intravascular coagulation, acute renal insufficiency

Acute renal insufficiency is associated with disseminated intravascular coagulation.

Drug-related immune hemolytic anemia symptoms common symptoms hemolytic anemia chills high fever renal failure drug allergic reaction intravascular clotting shock

Patients with hemolysis have a history of medication in the past, and may occur during long-term medication. Some patients have drug allergic reactions such as rash and fever before hemolysis. Hemolysis is usually subacute, mild, mainly extravascular. Relieve after a few days or weeks of withdrawal.

Patients often have acute intravascular hemolysis with chills, high fever, vomiting and low back pain. Some patients may develop acute renal failure, shock and disseminated intravascular coagulation. The dose of drugs required for hemolysis is small, but must be in the past. History of medication.

It is clinically found that after treatment with methyldopa, asymptomatic anti-human globulin test positive cases up to 15%, generally 3 to 6 months of medication, most after half a year, there are also reports of positive reactions after 3 years of medication It takes 0.5 to 1 year for the anti-human globulin test to be negative after stopping the drug administration, but only 1% of hemolytic anemia occurs after administration of methyldopa, and most of the anemia is mild to moderate, because the erythrocytes adsorbed by IgG are in vivo. Destroyed by spleen phagocytic cells.

Examination of drug-related immune hemolytic anemia

1. Peripheral blood: Red blood cells, reduced hemoglobin, visible spherical cells, increased eosinophils, increased total number of white blood cells and platelets.

2. Anti-human globulin is positive both directly and indirectly, usually IgG type.

3. The increase of blood bilirubin is mainly caused by the increase of indirect bilirubin.

4. Increased serum free hemoglobin, decreased haptoglobin and so on.

According to clinical manifestations, symptoms and signs can be selected for X-ray, B-ultrasound, electrocardiogram, liver and kidney function and DIC.

Diagnosis and identification of drug-related immune hemolytic anemia

Anyone with autoimmune hemolytic anemia should be asked carefully about the medical history. Those who have a history of taking medications are generally not difficult to diagnose. In addition, the hemolysis disappears rapidly after stopping the drug, and the diagnosis can be established. The laboratory test can confirm the nature of hemolysis and the drug. Relationship.

The anti-human globulin test has a certain value in the diagnosis of drug-related immunoremediation, and the anti-human globulin test is positive for hapten-type measurable serum antibody antibodies such as penicillin antibody or erythrocyte; autoimmune test The type is positive both with and without the anti-human antiglobulin test. These characteristics are combined with the cold agglutinin and DL test negative, and it is not difficult to identify with the idiopathic temperature antibody type and the cold antibody type AIHA.

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