Iron deficiency anemia

Introduction to iron deficiency anemia Irondeficiency anemia (IDA) is a common anemia caused by the lack of iron in the body, which affects the synthesis of hemoglobin. Before the production of red blood cells is restricted, the iron storage in the body is exhausted, which is called iron deficiency. This anemia is characterized by the lack of stainable iron in the bone marrow, liver, spleen and other tissues, serum iron concentration and serum transferrin saturation are reduced. Typical cases of anemia are small cell hypopigmentation. The disease is a common type of anemia, which is common in all parts of the world. The causes of iron deficiency anemia are: first, the increased demand for iron and insufficient intake, second, poor absorption of iron, and third, excessive blood loss, etc. Hemoglobin and red blood cells survive and anemia occurs. basic knowledge The proportion of illness: 0.3% Susceptible people: no specific population Mode of infection: non-infectious Complications: intracranial hypertension syndrome

Causes of iron deficiency anemia

Insufficient iron demand and insufficient intake (30%):

Children need increased iron during the growing period and during lactation, especially in premature infants, twins or mothers with anemia. The original iron storage of infants is insufficient. If only those with less iron are fed, after the teething If you don't replenish eggs, vegetables, meat and animal liver, etc., you can cause iron deficiency anemia, increase the amount of iron in pregnancy and lactation, plus gastrointestinal dysfunction during pregnancy, stomach acid. Lack, affecting iron sleep, especially after multiple pregnancies, it is easy to cause iron deficiency anemia, adolescents due to rapid growth, increased iron demand, especially young women, due to menstrual blood loss, if the food consumed for a long time is insufficient Iron deficiency can also occur. The most common cause is insufficient iron content in food, partial eclipse or malabsorption. Heme iron in food is easily absorbed, and is not affected by food composition and gastric acid. Non-heme iron needs to be first. It can be absorbed by Fe2, and the absorption of iron, vegetables, cereals, phosphates in the tea, phytic acid, tannins, etc. can affect the absorption of iron.

The daily iron requirement for adults is about 1 to 2 mg, and the male 1 mg/d is enough. The need for iron for women of reproductive age and for adolescents with growth and development should be 1.5 to 2 mg/d, such as iron in the diet and stored in the body. Iron is sufficient, and iron deficiency is rarely found. Other causes of insufficient iron intake are drug or gastrointestinal disorders that affect iron absorption. Some metals such as gallium and magnesium are ingested, and calcium carbonate in antacids. And magnesium sulfate, H2 inhibitors taken during ulcer disease, can inhibit iron absorption, atrophic gastritis, gastric acid and duodenal surgery after the reduction of gastric acid affects iron absorption, etc., are the cause of insufficient iron intake In addition, the average blood loss during pregnancy is 1300ml (about 680mg iron). It needs 2.5mg of iron per day. In the 6th month after pregnancy, 3 to 7mg of iron is needed every day, and the requirement of iron during lactation is increased by 0.5~1mg/d. Insufficient supplementation will lead to a negative balance of iron. For example, the need for iron is increased in multiple pregnancies. Each blood donation of blood donors is equivalent to 200mg of lost iron, about 8% of male blood donors and 23% of female blood donors. Serum ferritin is reduced, as many times in the short term , The situation will be worse.

Excessive storage of iron (30%):

Because 2/3 of the total iron in the body is present in the red blood cells, repeated, a large amount of blood loss can significantly consume iron stores in the body, hookworm disease causes chronic small amount of intestinal bleeding, repeated upper bleeding of upper gastrointestinal ulcer, many years of anorectal bleeding or Long-term loss of excessive menstrual flow in women eventually leads to insufficient iron storage in the body, resulting in iron deficiency anemia, in addition, paroxysmal nocturnal hemoglobinuria, mechanical hemolysis caused by artificial mechanical heart valves, and idiopathic lung Hemosiderin can cause anemia due to long-term urinary iron loss. Normal people lose about 1mg of iron from the gastrointestinal tract, urinary tract and skin epithelial cells every day. Women in menstruation, childbirth and breastfeeding There is more iron loss, and excessive iron loss in the clinic is often caused by gastrointestinal bleeding in men, while women are often due to menorrhagia.

Excessive iron loss (30%):

Excited iron can be lost with aging and detachment of gastrointestinal epithelial cells. In atrophic gastritis, major gastrectomy and steatorrhea, epithelial cell renewal rate is increased, so free iron loss is also increased, and iron deficiency not only causes blood redness. The synthesis of hormones is reduced, and the activity of iron-containing enzymes (such as cytochrome oxidase) in red blood cells is reduced, which affects the electron transport system, which can cause abnormalities in lipids, proteins and sugar metabolism, leading to abnormal red blood cells, which are easily broken in the spleen and shortened. Its life cycle. The iron in the human body is in a closed loop. Under normal circumstances, the absorption and excretion of iron maintains a dynamic balance. The human body generally does not lack iron. It only causes an increase in iron intake and chronic blood loss. Long-term iron negative balance leads to iron deficiency, and the cause of iron deficiency can be divided into two categories: insufficient iron intake and excessive loss.

[Pathogenesis]

Iron is an essential trace element in the human body. It exists in all living cells. In addition to participating in hemoglobin synthesis, iron participates in some biochemical processes in the body, including mitochondrial electron transfer, catecholamine metabolism and DNA synthesis. Iron, such as peroxidase, cytochrome c reductase, succinate dehydrogenase, ribonucleic acid reductase and xanthine oxidase and other proteases and oxidoreductases have iron, such as lack, will affect the redox function of cells , causing many aspects of dysfunction.

Decreased activity of iron-containing enzyme, affecting the oxidative glycolysis cycle of cell mitochondria, keratinizing and degeneration of epithelial cells with rapid metabolism, atrophy of digestive system mucosa, reduction of gastric acid secretion, dehydrogenation of -glycerophosphate in skeletal muscle during iron deficiency Reduced enzymes, easy to cause increased accumulation of lactic acid after exercise, so that muscle function and physical strength decline, iron-containing monoamine oxidase plays an important role in the synthesis and decomposition of some nerve transport agents (such as dopamine, norepinephrine and serotonin) In the absence of iron, the activity of monoamine oxidase is reduced, which may affect the development and intelligence of the nerve.

The developing red blood cells require iron, protoporphyrin and globin to synthesize hemoglobin, and hemoglobin synthesis is insufficient to cause hypopigmentation anemia. There is still a different view on the relationship between iron deficiency and infection, macrophage function and spleen during iron deficiency. Natural killer cell activity is obviously impaired; neutrophil myeloperoxidase and oxygen respiratory burst function are reduced; lymphocyte transformation and migration inhibitory factors are blocked, and cellular immune function is decreased, but others emphasize that iron is also a bacterial growth Needed, it is believed that iron deficiency has a certain protective effect on the body, and iron is more prone to infection than iron deficiency.

Iron deficiency anemia prevention

Iron deficiency anemia is mostly preventable.

1. Do a good job in feeding guidance: promote breastfeeding, and timely add supplemental foods with high iron content and high iron absorption rate, such as liver, lean meat, fish, etc., and pay attention to the reasonable mix of diets, and appropriate iron supplements for pregnant and lactating women. .

2, infant foods add appropriate amount of iron for reinforcement.

3, for premature infants, low birth weight infants should be given early iron prevention.

4. Large-scale parasite prevention and control work should be carried out in the hookworm endemic area.

5, timely cure a variety of chronic gastrointestinal bleeding diseases.

Iron deficiency anemia complications Complications intracranial hypertension syndrome

Easy to be infected, such as with stomatitis, glossitis, etc., anemia can be complicated by anemia.

Symptoms of iron deficiency anemia Common symptoms Nail lifted index finger nails depression syncope red blood cells low abdominal distension swallowing difficulties tinnitus heart failure hook dermatitis erythrocytosis

The severity of clinical manifestations is mainly determined by the degree of anemia and its speed. Acute blood loss is caused by rapid disease. Even if the degree of anemia is not serious, it will cause obvious clinical symptoms. However, due to the slow onset of chronic anemia, the human body can gradually adapt through adjustment. symptom.

1, symptoms

Faint sallow or pale, tired and tired, loss of appetite, nausea, bloating, diarrhea, dysphagia, dizziness, tinnitus, even fainting, a little activity, irritability, palpitations, angina pectoris, women with coronary arteriosclerosis, can cause angina, women There may be irregular menstruation, amenorrhea and so on.

Special manifestations of iron deficiency include: angular cheilitis, tongue mastoid atrophy, glossitis, severe iron deficiency can have key nails (anti-armor), loss of appetite, nausea and constipation, and European patients often have difficulty swallowing. Oral keratitis and abnormal tongue, called Plummer-Vinson or Paterson-Kelly syndrome, which may be related to the environment and genes. The difficulty in swallowing is due to the formation of a mucosal network at the junction of the hypopharynx and esophagus, and even around the lumen. The formation of a cuff-like structure that binds the opening of the esophagus often requires surgery to break the mesh or expand the stenosis, and the supplement of iron alone does not help.

Non-anemia symptoms: Non-anemic symptoms of iron deficiency: children with growth retardation or abnormal behavior, manifested as irritability, irritability, lack of concentration in school and decreased academic performance. Peculiar food is a special manifestation of iron deficiency, or may be lack of The cause of iron, the mechanism of its occurrence is unclear, patients often can not control only eat a kind of "food", such as ice, clay, starch, etc., iron can disappear after treatment.

2, signs

Long-term patients may have nail shrinkage, not smooth, anti-A, pale skin mucous membrane, dry skin, dry hair loss, tachycardia, strong heart beat, systolic murmur can be heard in the apex or pulmonary flap area, serious Anemia can lead to congestive heart failure, edema can also occur, about 10% of iron deficiency anemia patients with mild swelling of the spleen, the reason is not clear, no special pathological changes in the patient's spleen, can disappear after iron deficiency correction, Retinal hemorrhage and exudation can be seen in a small number of patients with severe anemia.

Iron deficiency anemia check

1. The blood picture shows typical small cell hypochromic anemia (MCV<80fl, MCH<27pg, MCHC<30%). The degree of red blood cell index change is related to the time and extent of anemia. The red blood cell width distribution (RDW) is in iron deficiency. The diagnosis of anemia is difficult to determine, the normal (13.4 ± 1.2)%, the iron deficiency anemia is 16.3% (or > 14.5%), the specificity is only 50% ~ 70%, red blood cells staining in the blood film, The central light-stained area is enlarged, the size is different, most of the reticulocytes are normal or slightly increased, the white blood cell count is normal or slightly reduced, the classification is normal, the platelet count is often high in patients with bleeding, and is mostly low in infants and children.

2, bone marrow bone marrow examination is not necessarily required, unless it is necessary to identify the anemia of other diseases, bone marrow smear is proliferating active, young red blood cells are obviously proliferating, early red and young red blood cells are increased, chromatin particles are dense, cytoplasm Less, hemoglobin formation is poor, granulocyte and megakaryocyte cell lines are normal, iron granules are few or disappear, and extracellular iron is absent.

3, biochemical examination

(1) Determination of serum iron: serum iron decreased <8.95mol/L (50g/dl), total iron binding capacity increased>

64.44mol/L (360g/dl), so the transferrin saturation is reduced. Because the determination of serum iron is fluctuating, there are many influencing factors. When judging the results, it should be combined with clinical considerations, 2 to 3 days before women's menstruation. In the third trimester of pregnancy, serum iron and total iron binding are reduced, but not necessarily iron deficiency.

(2) serum ferritin determination: serum ferritin is lower than 14g / L, but can be associated with inflammation, tumors and infections, should be combined with clinical or bone marrow iron staining to determine, iron deficiency anemia in patients with bone marrow erythroid cells And extracellular iron staining is reduced or absent.

(3) Determination of erythrocyte free protoporphyrin (FEP): elevated FEP indicates that heme synthesis is disordered, and it is a sensitive method to reflect the presence of iron deficiency, but in the case of non-iron deficiency such as lead poisoning and iron pellets When the cell is anemia, FEP will also increase, and should be considered in combination with clinical and other biochemical tests.

(4) Determination of erythrocyte ferritin: radioimmunoassay or enzyme-linked immunosorbent assay can be used to measure erythrocyte alkaline ferritin, which can reflect the status of iron storage in the body, such as <6.5g/erythrocyte, indicating iron deficiency, the result is related to serum ferritin Parallel, the effect of inflammation, tumor and liver disease is small, but the operation is more complicated and can not be used as a routine.

Small cell hypochromic anemia: male hemoglobin <120g / L, female hemoglobin <110g / L, maternal hemoglobin <100g / L; MCV <80fl, MCH <26pg, MCHC <0.31; morphology can have significant hypopigmentation, serum iron <10.7mmol / L, total iron binding capacity> 64.44mmol / L, transfer protein saturation <0.15, serum ferritin <14mg / L, bone marrow iron staining showed that bone marrow granules can be stained with iron disappeared, iron red blood cells <15% .

In order to clarify the cause or primary disease of anemia, it is necessary to carry out: multiple fecal occult blood, urine routine examination, if necessary, further check liver and kidney function, gastrointestinal X-ray, gastroscopy and corresponding biochemical, immunological examination, etc. .

Diagnosis and diagnosis of iron deficiency anemia

Diagnostic criteria

1. Bloody mild anemia is positive cell positive pigment anemia. Severe anemia is typical small cell hypochromic anemia. Erythrocyte average volume (MCV) <80fl, red blood cell mean hemoglobin content (MCH) <28pg, red blood cell mean hemoglobin concentration MCHC< 30%, the red blood cells in the blood film are of different sizes, the small ones are more common, the shape is irregular, a few elliptical shapes, target shapes and irregular red blood cells appear, the red stained area of the red blood cells expands, and even becomes a narrow ring, reticulocytes Most of them are normal and can be temporarily elevated when acute blood loss occurs.

2, bone marrow like bone marrow showed active cell proliferation, mainly for young red blood cells, young red blood cells smaller, cytoplasmic development imbalance.

3. Serum iron serum iron is significantly reduced.

4, erythrocyte protoporphyrin reduced iron synthesis due to iron deficiency, iron deficiency anemia erythrocyte free protoporphyrin 500g / L (normal 200 ~ 400g / L).

5, small cell hypochromic anemia hemoglobin (Hb) male less than 120g / L, female less than 110g / L; MCV less than 80fl, MCH less than 26pg, MCHC less than 0.31.

6, there are clear causes of iron deficiency and clinical manifestations.

7. The serum iron is less than 10.7 mol/L (60 g/dl), and the total iron binding force is greater than 64.44 gmol/L (360 g/dl).

8. The transport protein saturation is less than 15%.

9, the bone marrow extracellular iron disappeared, the intracellular iron was less than 15%.

10. The cell free protoporphyrin (FEB) is greater than 0.9 mol/L (50 g/dl).

11. Serum ferritin (SF) is less than 14 g/L.

12, iron treatment is effective.

13, chronic infectious anemia.

14, iron granule anemia.

15, vitamin B6 reactive anemia.

16, thalassemia.

Careful inquiry and analysis of medical history, plus physical examination can get clues to diagnose iron deficiency anemia, confirm the diagnosis must be confirmed by the laboratory, clinically, iron deficiency and iron deficiency anemia are divided into: iron deficiency, iron deficiency erythropoiesis And the three stages of iron deficiency anemia, the diagnostic criteria are as follows:

1. Iron deficiency or potential iron deficiency At this time, only the consumption of iron stored in the body is met, and it can be diagnosed according to (1) plus any one of (2) or (3).

(1) There are clear causes and clinical manifestations of iron deficiency.

(2) Serum ferritin <14 g / L.

(3) Bone marrow iron staining showed that iron granule cells were <10% or disappeared, and extracellular iron was absent.

2, iron deficiency erythropoiesis refers to the red blood cells intake of iron is less than normal, but the reduction of intracellular hemoglobin is not obvious, in line with the diagnostic criteria of iron deficiency, and any of the following can be diagnosed.

(1) Transferrin saturation <15%.

(2) Erythrocyte free protoporphyrin > 0.9 mol / L or > 4.5 g / g Hb.

3, iron deficiency anemia red blood cell red blood cell reduction is obvious, showing small cell hypochromic anemia, the diagnosis is based on: 1 in line with the diagnosis of iron deficiency and iron deficiency erythropoiesis; 2 small cell hypochromic anemia; 3 iron treatment effective .

Diagnostic evaluation:

(1) Determination of serum iron is affected by many factors: it cannot be used as an indicator for the diagnosis of iron deficiency. It should be emphasized that serum total iron binding capacity is >64.44mol/L (360g/L) and transferrin saturation is <15%. Diagnosed as iron deficiency, serum iron alone, can not be diagnosed as "iron deficiency", because it is not easy to distinguish with other iron utilization disorders caused by serum iron (such as chronic disease anemia), as well as total iron binding capacity <64.44mol / L (360 g / L), transferrin saturation > 15%, can not be diagnosed as "iron deficiency."

(2) In the past, it was thought that the staining of bone marrow iron showed that the disappearance of bone marrow irritable iron was the "gold standard" for the diagnosis of iron deficiency: it was rarely used after the determination of ferritin by radioimmunoassay in the 1970s, because the conditions of bone marrow iron staining required production conditions. High, and often affected by the inconsistent results of bone marrow samples from different parts, so the clinical serum ferritin has replaced the bone marrow iron staining method to become the "gold standard" for the diagnosis of iron deficiency. It is currently considered that serum ferritin 1g / L is equal to 100mg Iron storage.

(3) Many patients with iron deficiency anemia often have a combination of various chronic diseases (including inflammation, tumor and infection): serum ferritin levels are affected by chronic diseases, and patients with chronic diseases are associated with iron deficiency. The standard of serum ferritin has not been unified (some literatures believe that it should be greater than 60-140g/L). In addition to careful analysis of clinical and laboratory findings, it is best to further measure ferritin receptors. Increase) or erythrocyte ferritin (<5g/ml cells are iron deficiency).

Differential diagnosis

Mainly differentiated from other small cell hypochromic anemia.

1, globin-producing anemia (thalassaemia) often has a family history, most of the target red blood cells can be seen in the blood, hemoglobin electrophoresis can be seen in fetal hemoglobin (HbF) or hemoglobin A2 (HbA2) increased, the patient's serum iron and iron Protein saturation, bone marrow can increase iron.

2, chronic disease anemia serum iron decreased, but the total iron binding capacity will not increase or decrease, so the transferrin saturation is normal or slightly increased, serum ferritin is often increased, the number of iron granules in the bone marrow is reduced, macrophages The inner iron particles and hemosiderin particles increased significantly.

3, iron granulocyte anemia is rare in clinical, occurs in the elderly, mainly due to iron utilization disorders, often small cell positive pigment anemia, increased serum iron and total iron binding capacity, so transferrin When the saturation is increased, the iron particles and iron granules in the bone marrow are significantly increased, and most of the ring-shaped iron granule cells are observed, and the serum ferritin level is also increased.

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