OVERVIEW

What is anemia?

Anemia is a clinical syndrome characterized by insufficient red blood cells or hemoglobin in the peripheral blood, leading to inadequate oxygen supply to tissues and organs. It may cause symptoms such as headaches, dizziness, insomnia, palpitations, and pale skin or mucous membranes^[1].

The causes of anemia mainly include iron deficiency, folate deficiency, vitamin B12 deficiency, pregnancy, viral infections, and prolonged exposure to X-rays or radium. Additionally, some types of anemia can also be caused by genetic factors^[1].

Due to the diverse causes of anemia, there is no uniform treatment method. Treatment is generally tailored to the underlying cause, and symptoms can often be alleviated after treatment^[1].

Is anemia common?

Yes. However, there is no latest authoritative data on its specific incidence rate. According to the 2010–2012 China Nutrition and Health Surveillance, the prevalence of anemia among urban residents (excluding pregnant women) in China was 9.7%^[2], meaning that 97 out of every 1,000 urban residents had anemia.

Is anemia hereditary?

Not necessarily.

Anemia caused by malnutrition, such as iron-deficiency anemia or megaloblastic anemia, is usually not hereditary. However, certain types of anemia, such as thalassemia (a form of hemolytic anemia), have a familial genetic predisposition^[1].

SYMPTOMS

What are the manifestations of anemia?

The symptoms of anemia are generally related to the cause of anemia, the degree of hemoglobin decline, and the speed of anemia onset. The specific manifestations are as follows:

• Skin and mucous membranes: After anemia, the complexion, conjunctiva, nail beds (nail color), and lip color may become pale. If anemia progresses, the skin may become rough and cracked^[1].
• Nervous system: Symptoms include dizziness, tinnitus, insomnia, fainting, visual blind spots, memory decline, and numbness in the extremities. Children with anemia may also exhibit restlessness and crying.
• Respiratory system: Manifested as increased and deeper breathing after activity. Severe anemia may also cause shortness of breath and orthopnea (a condition where the patient is forced to sit or recline to relieve difficulty breathing)^[1].
• Circulatory system: Symptoms include a faster heartbeat and palpitations at rest or after activity^[1].
• Digestive system: Manifested as indigestion, bloating, loss of appetite, constipation, or diarrhea. Patients with iron-deficiency anemia may also experience a sensation of swallowing foreign objects^[1]. Pica (eating non-food items like dirt, hair, or leaves) is a specific symptom of iron-deficiency anemia.
• Urinary system: Patients with severe hemorrhagic anemia may experience oliguria or anuria (reduced or no urine output)^[1].
• Reproductive system: Women may experience menstrual cycle irregularities, increased or decreased menstrual flow^[1].
• Immune system: Reduced immunity, particularly noticeable in children, leading to frequent illnesses^[1].

Anemia is only detected during a check-up, but there are no symptoms. How should this situation be viewed?

Most cases of anemia are merely a manifestation of an underlying disease. As long as the peripheral blood hemoglobin concentration is below the normal range, even if clinical symptoms are not obvious, anemia can still be diagnosed. More importantly, the cause of anemia or the primary disease leading to anemia should be identified.

What serious consequences can anemia lead to?

Anemia can affect the prognosis of disease treatment, increase mortality and morbidity rates in women and children, and impair cognitive and physical development in children^[3].

Does anemia always cause pale lips?

In the absence of cold exposure or hunger, if the lips become noticeably paler than before, anemia should be considered. The simplest way to confirm this is to get a blood test at a hospital. Of course, some people naturally have paler lips than others. If the blood test results are normal, there is no need for concern.

CAUSES

What Are the Common Causes of Anemia?

Different types of anemia have different causes. The following are some of the more common ones in daily life:

• Iron-deficiency anemia: Mainly caused by insufficient iron intake, impaired iron absorption, or excessive iron loss^[1].
• Insufficient iron intake: Occurs when iron demand increases but iron-rich foods are not supplemented in time.
• Impaired iron absorption: Particularly after gastrectomy, food enters the intestines too quickly, reducing iron absorption and leading to anemia.
• Excessive iron loss: Chronic blood loss without correction can also cause anemia.
• Megaloblastic anemia: Primarily caused by folate or vitamin B12 deficiency^[1]. Long-term lack of folate- or vitamin B12-rich foods may lead to anemia.
• Aplastic anemia: May be related to viral infections (e.g., hepatitis virus), use of chloramphenicol antibiotics, sulfonamides, chemotherapy drugs, or prolonged exposure to radiation (e.g., X-rays, radium)^[1].
• Hemolytic anemia: May be associated with genetics, blood type incompatibility, diseases (e.g., disseminated intravascular coagulation, sepsis, malaria), or physical/chemical factors (e.g., extensive burns, nitrite poisoning)^[1].
• Hemorrhagic anemia: Both acute massive blood loss and chronic long-term blood loss can lead to anemia^[1].

Who Is Prone to Anemia?

• Infants, pregnant and lactating women: These groups have higher iron demands and are more likely to develop anemia if iron-rich foods are not supplemented in time^[1].
• Adolescents: Often develop anemia due to picky eating habits^[1].
• Individuals who have undergone gastrectomy: Due to rapid food passage into the intestines post-surgery, iron absorption decreases, increasing anemia risk.
• Patients with chronic gastrointestinal bleeding: Including those with hemorrhoids, gastroduodenal ulcers, or gastrointestinal tumors. Chronic blood loss leads to iron depletion and anemia^[1].
• Fetuses with blood type incompatibility to their mothers: Mainly occurs when the mother is type O and the fetus is type A or B. Type O mothers produce antibodies against other blood types before the first pregnancy, leading to fetal hemolytic anemia, neonatal jaundice, or even heart failure in severe cases^[4].

Additionally, individuals with heavy menstruation, long-term hemodialysis, a family history of hereditary anemia, prolonged use of chemotherapy or other anemia-inducing drugs, sepsis, malaria, or extensive burns are also prone to anemia^[1].

DIAGNOSIS

What are the diagnostic criteria for anemia?

Clinically, hemoglobin concentration in the blood is generally used to evaluate whether anemia has occurred^[1].

Hematologists in China believe that at sea level in China, anemia is defined as hemoglobin <120 g/L in adult males, hemoglobin <110 g/L in adult females (non-pregnant), and hemoglobin <100 g/L in pregnant women^[1].

Internationally, the diagnostic criteria established by the World Health Organization in 1972 are generally used as the basis. At sea level, anemia is defined as hemoglobin <110 g/L in children aged 6 months to <6 years, hemoglobin <120 g/L in children aged 6–14 years, hemoglobin <130 g/L in adult males, hemoglobin <120 g/L in adult females, and hemoglobin <110 g/L in pregnant women^[1].

How is the severity of anemia classified?

Since the clinical manifestations of anemia do not directly correspond to its severity, the classification of anemia is not based on clinical symptoms but on hemoglobin concentration levels. For adults:

• Mild anemia: Hemoglobin concentration >90 g/L;
• Moderate anemia: Hemoglobin concentration between 60–90 g/L;
• Severe anemia: Hemoglobin concentration between 30–60 g/L;
• Very severe anemia: Hemoglobin concentration <30 g/L^[1].

Severe and very severe anemia can cause serious harm to health, especially very severe anemia, which can be life-threatening and requires immediate corrective treatment.

What tests should be done to diagnose anemia?

In addition to evaluating the patient's symptoms and medical history (including family history to understand genetic predisposition, nutritional history to assess malnutrition, menstrual history to evaluate blood loss, past medical history to identify chronic blood loss conditions, medication history to check for anemia-inducing drugs, and exposure history to risk factors such as radiation), the following tests are required to diagnose anemia^[1].

• Peripheral blood test: The most direct and important test for diagnosing anemia, which not only measures red blood cell and hemoglobin levels to assess severity but also evaluates red blood cell size to roughly determine the cause of anemia^[1].
• Peripheral blood smear: Examines the quantity and morphology of red blood cells, white blood cells, and platelets, and checks for abnormal cells^[1].
• Bone marrow examination: Involves extracting a bone marrow sample via aspiration for analysis, including bone marrow smear classification and biopsy. The smear reflects cell growth and morphological changes, while the biopsy assesses the structure, cellular composition, and morphological changes of hematopoietic tissue^[1].

Additional tests may include serum iron, folate, and vitamin B12 levels, liver and kidney function tests, genetic testing, fecal occult blood tests, and endoscopy to identify the underlying cause of anemia^[1].

TREATMENT

Which department should I visit first for anemia?

Hematology department.

If the anemia is caused by acute bleeding, you can also go to the emergency department first.

How is anemia treated?

The key to treating anemia is identifying the cause and then targeting the underlying condition to effectively correct the anemia.

Medication:

• Iron supplements: Commonly used options include ferrous sulfate and iron dextran, which replenish the body's iron levels and are suitable for patients with iron-deficiency anemia. However, side effects like nausea, vomiting, and teeth discoloration may occur, so it's best to take them after meals^[1].
• Folic acid and vitamin B12: These supplements are used for patients with megaloblastic anemia. Possible side effects include bloating and nausea^[1].
• Cyclosporine + androgens: Cyclosporine suppresses T-cell destruction of hematopoietic cells, restoring normal blood cell production, while androgens stimulate bone marrow hematopoiesis. This combination is effective for aplastic anemia but may cause digestive discomfort and liver/kidney damage^[1].
• Corticosteroids: Prednisone and dexamethasone are commonly used to reduce immune responses in autoimmune hemolytic anemia. Side effects may include weight gain, edema, muscle weakness, nausea, and vomiting. Long-term high-dose use is not recommended^[1].

Surgical treatment:

• Splenectomy: The spleen is a major site of red blood cell destruction, so its removal can improve anemia. This is suitable for autoimmune hemolytic anemia patients who don’t respond to or tolerate hormone therapy^[1].
• Hematopoietic stem cell transplantation: This can cure aplastic anemia, but patients must undergo high-dose chemotherapy before receiving stem cells. Post-transplant complications like graft-versus-host disease (skin redness, itching, diarrhea, nausea, vomiting) may occur^[5].

Symptomatic treatment: For patients with severe anemia symptoms.

• Patients with severe anemia or acute massive blood loss require immediate blood transfusion and/or hemostasis to restore blood volume and correct anemia^[1].
• Those with anemia and infections need anti-infection therapy^[1].

Can dietary adjustments treat anemia?

For some patients, dietary changes can alleviate or even cure anemia. For example, iron-rich foods can improve or resolve nutritional iron-deficiency anemia^[1].

What is blood transfusion therapy for anemia?

Transfusion is an important treatment but has many side effects and complications, so indications must be strictly followed.

Patients with hemoglobin below 70 g/L (severe or very severe anemia) or acute blood loss exceeding 30% of total volume generally require transfusion^[6,7].

In clinical practice, a comprehensive evaluation is needed. For chronic conditions like aplastic anemia, patients may tolerate low hemoglobin levels without symptoms and may not require immediate transfusion^[6].

When should anemia patients avoid or limit transfusions?

Treatment should focus on addressing the underlying cause. Transfusion is reserved for emergencies or when other treatments fail. Caution is needed in:

• Patients with uremia or hyperkalemia should receive minimal transfusions^[6].
• Autoimmune hemolytic anemia patients should avoid transfusions when possible. If necessary, pre-transfusion anti-allergy treatment and slow infusion are required^[6].
• For bone marrow transplant candidates, transfusions should be minimized. If unavoidable, irradiated blood is preferred^[6].
• Patients with heart failure or extreme anemia should receive smaller, slower transfusions^[6].

Can anemia be cured?

Nutritional anemia can be cured with adequate supplementation of deficient nutrients^[1].

For other types, prognosis depends on treating the underlying cause^[1].

DIET & LIFESTYLE

What should anemia patients pay attention to in their diet?

• Maintain a balanced diet with a mix of meat and vegetables, avoiding picky eating habits.
• Patients with iron-deficiency anemia should consume more iron-rich foods such as beef, chicken, and animal offal. For non-animal sources, opt for fresh leafy greens (spinach, amaranth, etc.), black fungus, seaweed, and black sesame seeds. Increase intake of vitamin C-rich foods like oranges, tomatoes, and other fresh fruits and vegetables, as vitamin C enhances iron absorption. Reduce consumption of coffee, cocoa, and strong tea, as these can inhibit iron absorption^[3,8].
• Patients with megaloblastic anemia should eat more folate-rich foods like soybeans, spinach, and celery, as well as vitamin B12-rich foods such as pork liver, jellyfish, and eggs^[8].

What should anemia patients pay attention to in daily life?

Since anemia reduces the body's tolerance to varying degrees, patients should prioritize rest, balance work and rest, and avoid excessive fatigue. Physical exertion should not lead to feelings of exhaustion or dizziness. Avoid heavy manual labor (e.g., lifting heavy objects) or increase rest periods during such tasks.

Engage in exercise to strengthen physical fitness and boost immunity. Middle-aged and elderly individuals can practice tai chi or square dancing, while younger people may choose jogging or yoga. Avoid intense or highly competitive sports like basketball or boxing.

PREVENTION

How to Prevent Anemia?

• Maintain a balanced diet with a reasonable mix of meat and vegetables, avoiding picky or selective eating.
• Infants should start complementary feeding in addition to breastfeeding after 6 months^[3].
• Schedule regular health check-ups for early detection and treatment. High-risk groups should increase check-up frequency.
• Patients with underlying conditions should seek medical attention promptly and actively treat the primary disease.
• Avoid excessive consumption of coffee, strong tea, and similar beverages^[5].