Anemia due to infectious disease

Introduction to anemia caused by infectious diseases Anemia caused by infectious diseases is caused by the infiltration of many pathogenic microorganisms into the human body, which can reduce the production of red blood cells, damage or blood loss during the process of causing inflammation or infection, and the resulting anemia is called infectious anemia. basic knowledge The proportion of illness: 0.36% Susceptible people: no specific population Mode of infection: non-infectious Complications: shock heart disease

Causes of anemia caused by infectious diseases

Blood loss (30%):

Gastrointestinal infection combined with hemorrhage is common in hookworm disease, Shigella dysenteriae caused by Shigella dysenteriae, typhoid fever, Helicobacter pylori, etc. can cause bleeding caused by stomach and duodenal ulcer, bacterial infection often causes cystitis often hematuria, lung M. tuberculosis and Pseudomonas infection can cause hemoptysis caused by lung cavity. The clinical manifestations of blood loss caused by infection are often acute. Some patients show chronic blood loss, and the symptoms are the same as iron deficiency anemia.

Reduced erythropoiesis (20%):

Many infectious diseases can inhibit the bone marrow hematopoietic progenitor cells to varying degrees. For example, this inhibition is mainly directed to the red blood cell line, that is, anemia, such as involvement of the myeloid cell line or megakaryocyte cell line, can lead to the reduction of white blood cells and thrombocytopenia.

Increased red blood cell destruction (10%):

When the body is infected by bacteria, viruses or protozoa, infectious diseases such as INF-, IL-1, TNF and other cytokines can activate mononuclear macrophages, and the phagocytic ability of macrophages is enhanced to make red blood cells. In the spleen, the liver is destroyed too much, and extravascular hemolysis can be produced. In addition, due to the direct action of the pathogen itself or its secreted toxins and other products, or the indirect effects caused by the immune response of the body, the red blood cells are rapidly destroyed and acute hemolytic activity occurs. Anemia, many pathogenic microorganisms can cause hemolytic anemia (Table 2), but the mechanisms by which they cause anemia vary, and can be divided into the following cases:

(1) Direct destruction of red blood cells by pathogenic microorganisms in red blood cells.

(2) Hemolytic anemia involved in immune mechanisms: Many hemolytic anemia associated with infection are involved in immune mechanisms and can be classified into the following three types.

1 Autoimmune: pathogenic microorganisms or their products stimulate the body to produce special antibodies, which bind to certain proteins on the surface of red blood cells, leading to autoimmune hemolytic anemia. The factors that stimulate antibody production do not need to persist. Hemolytic anemia can be divided into: IgM Type of intravascular hemolysis, cold antibody type; IgG type extravascular hemolysis type, mostly warm antibody type, most of the infection-induced autoimmune hemolytic anemia is cold antibody type, also known as cold agglutinin disease, the most common induction The cause of cold agglutinin disease is infectious mononucleosis caused by mycoplasmal pneumonia and EB virus infection. The two produce IgM type antibodies against I, i antigen on the surface of red blood cells. After antigen and antibody are combined, complement is fixed and hemolysis is produced. Other infections that can cause cold agglutination include mumps, cytomegalovirus, Legionella, and the like.

2 immune complex type: its mechanism is the infection of the pathogenic microorganism or anti-infective drug as an antigen to stimulate the body to produce antibodies, antigen and antibody binding on the surface of red blood cells, fixed complement to produce hemolysis, can occur in children with Haemophilus influenzae caused by meninges Inflammation, in addition, anti-infective drugs such as quinine, quinidine, sulfonamide, pipemidic acid and other drugs can also cause this type of anemia.

3 Lectin: The T antigen on the normal erythrocyte membrane is covered by glycogen. After infection, the glycogen on the erythrocyte membrane is hydrolyzed by the enzyme produced by the bacteria, which exposes the T antigen and can bind to various antibodies in plasma, such as IgM type. The antibody allows red blood cells to aggregate and eventually hemolyze.

(3) Hemolytic anemia caused by enzyme deficiency in red blood cells: red blood cells rely on reductase to fight pathogenic microorganisms and drug oxidation, while glucose-6-phosphate dehydrogenase (G6PD) is a major anti-oxidation reductase in cells. Participate in the metabolism of glucose pentose phosphate pathway in red blood cells, maintain the stable glutathione (GSH) produced in cells at a stable level, GSH protects hemoglobin from oxidation, G6PD deficiency patients, neutrophils during infection The direct oxidation of a large number of peroxides and some anti-infective drugs can make hemoglobin into methemoglobin. Due to the lack of G6PD, methemoglobin and hydrogen peroxide, globin and heme separate to form Heinz bodies, Heinz body adsorption On the erythrocyte membrane, the membrane becomes stiff and easily ruptured by mononuclear macrophages in the spleen to cause extravascular hemolysis.

(4) Hemolytic anemia caused by pathological changes: tissue damage and degeneration caused by infection directly or indirectly, such as hemolytic uremic syndrome, disseminated intravascular coagulation, bacterial endocarditis, hypersplenism, hemolytic uremic Syndrome syndrome often occurs in young people and children, infants and young children, often suffering from acute hemolysis, uremia and thrombocytopenia after non-specific infection. Pathogens are often Escherichia coli, Shigella dysenteriae and pneumococcus.

After prosthetic heart valve replacement, rheumatic heart valve disease, disseminated intravascular coagulation, hypersplenism and other pathological changes can increase red blood cell destruction.

Anemia prevention caused by infectious diseases

1. Insufficient storage of congenital iron. Such as premature birth, twins, mother anemia, will reduce the iron storage of newborns.

2. Rapid growth and development. From birth to 1 year old, the baby grows fastest, the blood volume increases rapidly, and the iron needs are high. Therefore, children who grow too fast are prone to iron deficiency.

3. Lack of iron in the diet. After the baby is born for 6 months, the hematopoietic material obtained from the mother is basically used up, and the human milk and milk contain little iron. Therefore, if the supplementary food is not added in time, the simple feeding is easy to lack iron.

4, suffering from chronic diarrhea, etc., iron can not be well absorbed, resulting in iron deficiency. Finding the symptoms of anemia requires a long process.

Therefore, mild symptoms are often overlooked and often found to be moderately anemia. Common symptoms are irritability or lack of energy, lack of activity, loss of appetite, pale skin and mucous membranes, and most pronounced lips, nails, and palms. Older children can explain symptoms such as dizziness, black eyes, inattention, and memory loss.

Anemia complications caused by infectious diseases Complications, shock, heart disease

In severe cases, shock can occur; anemia and heart disease.

1. Shock is a clinical syndrome characterized by acute and effective circulating blood volume caused by various serious pathogenic factors, with neuro-humoral factor imbalance and acute circulatory disorder. These pathogenic factors include major bleeding, trauma, poisoning, burns, asphyxia, infection, allergies, and heart pump failure.

2. The pathogenesis of anemia heart disease, mainly due to anemia, blood oxygenation capacity decreased, insufficient oxygen supply to the body system, increased cardiac output, increased cardiac load, compensatory hypertrophy and enlargement of the myocardium, and long-term myocardial infarction Degenerative degeneration occurs in hypoxia, which aggravates cardiac function compensation. Anemia heart disease showed high cardiac output and cardiac function changes, increased heart rate, and decreased peripheral circulation resistance.

Symptoms of anemia caused by infectious diseases Common symptoms Liver splenomegaly proteinuria hyperthermia pale pale jaundice shortness of fatigue shortness of cold war

1. Acute infection combined with anemia: its symptoms and signs are similar to the general anemia symptoms, but hemolysis and blood loss are often sudden attacks. Hemolysis is sometimes violent. Because a large number of red blood cells are hemolyzed in blood vessels, patients with anemia can be very serious, often Obvious low back pain and limb soreness, headache, chest tightness, belching, chills, high fever, obvious hemoglobinuria, physical examination can be found obvious jaundice, spleen can be swollen.

2. Chronic infection combined with anemia: its clinical manifestations are often masked by the primary disease. There is no special symptom of anemia. The severity of the symptoms is related to the degree of anemia. It is often fatigued, palpitations, shortness of breath, anorexia, paleness, etc. In addition, infection It can cause fever, aversion to cold, hepatosplenomegaly and so on.

Examination of anemia caused by infectious diseases

1. Anemia caused by acute infection

(1) Peripheral blood: anemia is positive cells, positive pigmented anemia, peripheral blood smears may have different blood cell morphological characteristics depending on the infection, such as: malaria can find malaria parasites in blood samples; broken red blood cells can be seen during hemolysis. Small spherical and other abnormal red blood cells, white blood cell count is often increased, but there are also reduced, neutrophils can have nuclear left shift, cells appear toxic particles, vacuoles, Döhle bodies, etc., platelet count can be normal or reduced.

(2) Increased serum total bilirubin and indirect reaction bilirubin, increased free hemoglobin, and decreased globin.

(3) The anti-globulin test for immunological hemolytic anemia can be positive: it can be divided into two types, IgG and IgM, and can also be negative for anti-globulin test, such as hemolytic anemia caused by anti-infective drugs.

2. Anemia caused by chronic infection

(1) Peripheral blood: Although anemia is classified as positive cells and positive pigmented anemia, many patients present with hypochromic anemia. The red blood cells are slightly different in blood samples, the center is lightly stained, and the average hemoglobin concentration of red blood cells is less than 31%. The average volume of red blood cells is less than 80fL, and white blood cells and platelets are elevated or decreased.

(2) Serum iron: total iron binding capacity decreased, iron saturation decreased, serum ferritin was normal, serum iron decreased immediately after infection, and total iron binding capacity began to decrease after 8-12 days, serum copper increased. , there is a certain auxiliary diagnostic value.

(3) The ratio of bone marrow nucleated red blood cells and bone marrow granules/red blood cells is almost normal, there is no obvious erythroid hyperplasia, iron granulocytes are decreased, and iron storage in mononuclear macrophages is increased.

(4) Shortening of red blood cell life The life of the red blood cells was shortened by using 59Cr-labeled red blood cells.

According to the condition, clinical manifestations, symptoms, signs, X-ray, B-ultrasound, electrocardiogram, biochemical and microbiological examination.

Diagnosis and diagnosis of anemia caused by infectious diseases

In addition to the above-mentioned diagnosis of anemia, the diagnosis of infectious anemia must exclude anemia caused by other causes, such as tumors, anemia caused by chronic renal failure, etc. The most important is the diagnosis of primary infectious diseases that cause anemia. .

Differential diagnosis

1. Dilute anemia: In patients with progressive tumors, especially myeloma and macroglobulinemia, increased plasma volume can lead to dilute anemia,

2. Non-infectious chronic blood loss and iron malabsorption: In addition to blood loss caused by infection, the identification of infectious anemia and chronic blood loss and iron malabsorption depends on the following points:

(1) The binding capacity of transferrin and total iron decreases in the former,

(2) The serum ferritin is normal or increased while the latter is decreased,

(3) Experimental iron supplementation is not effective for chronic infectious anemia, but has obvious curative effect on iron deficiency anemia.

3. Anemia caused by chronic renal failure: serum iron is normal or elevated, serum urea nitrogen and creatinine are elevated.

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