This overview explores the causes and treatments of different types of anemia, including iron-deficiency anemia, aplastic anemia, sickle cell anemia, pernicious anemia and more.
Anemia Definition: What Is Anemia?
Anemia is a condition that develops when your red blood cell count or hemoglobin is less than normal.
As the most common blood disorder, anemia is often associated with being tired and weak. The reason for this is that anemia occurs when your body doesn’t have adequate healthy red blood cells. Red blood cells carry oxygen to the body’s tissues.
Different Types of Anemia
In addition to iron-deficiency anemia (the most common type), there is aplastic anemia, sickle cell anemia, pernicious anemia, and anemia of chronic disease. Treatment for anemia is dictated by the type as well as the cause of the anemia.
What Are the Causes of Anemia?
While white blood cells fight infection and platelets help your blood clot, red blood cells carry oxygen throughout your body.
Hemoglobin is an iron-rich protein that’s found in red blood cells. Hemoglobin is what makes it possible for red blood cells to take oxygen from your lungs and carry it to places throughout your body. Hemoglobin also takes carbon dioxide from different areas of your body and brings it to your lungs so your lungs can get rid of it when you exhale.
Your bone marrow, which is in your large bones, produces red blood cells. However, vitamin B12, folate and other nutrients that we get from food are needed to produce hemoglobin and red blood cells.
In addition to not having enough red blood cells, you can also become anemic if your body gets rid of red blood cells, or if, when you bleed, your body loses red blood cells more quickly than they can be replaced. (2)
Signs and Symptoms of Anemia
Depending on the type of anemia you have, you may experience a variety of symptoms. The most common symptom of all anemias is weakness.
The Most Common Types of Anemia
Aplastic anemia is a blood disorder in which the body’s bone marrow — the soft tissue in the center of bones — doesn’t make enough healthy blood cells. Because of this, it is sometimes referred to as bone marrow failure.
While the condition is rare, each year, between 600 and 900 people in the United States are diagnosed with aplastic anemia, according to the Aplastic Anemia and MDS International Foundation. (3)
The disorder affects men and women equally, and most commonly develops in adults between ages 20 and 25, as well as those over 60, according to the National Institute of Diabetes and Digestive and Kidney Diseases. (4)
It’s often not known exactly what causes aplastic anemia, but it’s believed that the condition is either “acquired” or “inherited.”
Acquired aplastic anemia, which is more common than the inherited form, may result from:
- Toxins, including benzene (a chemical sometimes used in manufacturing and chemical synthesis), pesticides, and arsenic
- Chemotherapy and radiation therapy for cancer treatment
- Various infectious diseases, including hepatitis, HIV, and Epstein-Barr virus (a type of herpes virus), lupus, rheumatoid arthritis, or other autoimmune disorders (those in which the immune system attacks healthy cells)
- Certain drugs, including some antibiotics, immunosuppressants, and some nonsteroidal anti-inflammatory drugs (NSAIDs)
- Cancer that has spread to the bone
Causes of inherited aplastic anemia, which is rare and develops from genes that are passed down from parent to child, include:
- Fanconi anemia
- Diamond–Blackfan anemia
- Shwachman–Diamond syndrome
- Dyskeratosis congenita
- Skin rashes
These symptoms may be severe from the start, or gradually worsen over time.
Other symptoms include:
- Shortness of breath and chest pain
- Dizziness, especially after standing up from a sitting or lying position
- Pale skin
- Bruising or bleeding easily
- Uncontrollable bleeding
- Nosebleeds, bleeding gums, bloody stool, or heavy menstrual bleeding
- Cold feeling in your hands and feet
- Fever due to infection
- Recurring infections and/or flu-like symptoms
- The appearance of small red dots on the skin that indicates bleeding under the skin
- Rapid heart rate
Over time, severe heart issues may develop, such as arrhythmia (irregular heart beat), angina, enlarged heart, and heart failure.
While blood tests can detect low blood cell counts and the possibility of aplastic anemia, they cannot diagnose the disorder.
Diagnosis generally requires a bone marrow biopsy in which a special needle removes a small piece of bone marrow and bone, along with blood, for examination under a microscope.(6)
Sickle Cell Anemia
Sickle cell anemia is an inherited blood disorder characterized by both a deficiency of healthy red blood cells and painful episodes called sickle cell crises.
The disorder is caused by a mutation in the gene that tells the body to make hemoglobin, a protein found in red blood cells that binds to oxygen in the lungs and carries it to tissues throughout the body.
As a result of the mutation, the body produces a defective form of hemoglobin called hemoglobin S, which causes red blood cells to sickle, or develop a crescent shape.
Sickle cells are stiff and sticky and tend to block blood flow in the vessels of the limbs and organs, causing pain and raising the risk for infection.
Sickle cells also have a shorter life span than normal red blood cells, leading to an overall shortage of red blood cells and, consequently, anemia.
To have sickle cell anemia, a person must inherit two sickle hemoglobin genes, one from each parent.
A person who inherits a sickle hemoglobin gene from one parent and a normal hemoglobin gene from the other parent is said to have sickle trait.
People with sickle trait generally don’t have symptoms related to it, but they are at risk of developing certain medical problems, and they can pass on the sickle hemoglobin gene to their children.
Sickle cell anemia affects millions of people around the world. It’s most common in people of African, Middle Eastern, Mediterranean, Central and South American, and Asian Indian origin or descent.(7)
The prevalence of the gene mutation that causes sickle cell is higher in areas of the world where malaria is found. Researchers have found that having sickle cell trait offers some survival advantage against malaria.
West and Central Africa are particularly hard hit, with a form of sickle cell anemia affecting about 1 to 2 percent of all births, according to the Sickle Cell Disease Association of America. (7)
In the United States about 70,000 to 100,000 people have sickle cell anemia, and African-Americans are affected most often, with 1 out of 365 black babies born with sickle cell anemia, reports the National Heart, Lung and Blood Institute (NHLBI). (8)
Anemia Treatments and Complications
Symptoms of sickle cell anemia typically start after the fifth or sixth month of life. Common signs and symptoms include:
- Swollen hands and feet, particularly in babies
- Frequent infections, especially pneumonia
- Fatigue and weakness
- Episodes of pain, called sickle cell crises, occur when sickled red blood cells block blood flow to the limbs and organs
Improved treatments have given a better outlet for people with sickle cell anemia. As little as 40 years ago, almost 15 percent of children born with sickle cell anemia died before age 2, and many more died as teens, according to the NHLBI.
Now, because of improved treatments and care, people who have sickle cell anemia are living into their 40s and 50s, or longer.
Iron-deficiency anemia is a common type of anemia that occurs when your blood doesn’t have enough healthy red blood cells.
It’s the most common and widespread nutritional disorder in the world, and the World Health Organization states that this type of anemia largely contributes to more than 30 percent of the world’s population being anemic. (9)
Red blood cells carry oxygen to the body’s tissues and remove carbon dioxide. Not having enough working red blood cells may lead to tiredness and shortness of breath.
Iron-deficiency anemia usually develops over time as your body taps into the iron it has stored, then eventually runs out.
Low iron may be caused by an inadequate diet that lacks iron-rich foods. The following foods are high in iron:
- Dried fruits
- Dark green leafy vegetables, such as spinach and chard
- Iron-fortified foods, such as breads and cereals
Eating or drinking foods and drinks high in vitamin C, such as orange juice, broccoli, peppers, and more, can help your body absorb iron when you eat it.
Iron-Deficiency Anemia Quiz
Sometimes getting the right amount of iron from your diet isn’t enough if your body isn’t able to absorb it properly. For instance, people who’ve had intestinal surgery, such as gastric bypass, or those with Crohn’s disease or celiac disease, may have trouble absorbing iron. Iron absorption can also be limited by prescription medicines that reduce acid in the stomach. (10)
Blood loss is another cause of iron deficiency anemia because whenever you lose blood from your body, iron loss also occurs. If you don’t have enough iron stored in your body to make up for the iron lost in your blood, you can develop anemia.
- Heavy menstrual periods
- Bleeding fibroids (noncancerous growths) in the uterus
- Internal bleeding caused by an ulcer, colon polyp, colon cancer, urinary tract bleeding, or use of pain medications
- Injuries or surgery
- Repeated blood drawings
Symptoms of iron-deficiency anemia vary depending on how severe your anemia is. If you have mild to moderate iron-deficiency anemia, you may not have any signs or symptoms. But as the condition worsens, you may experience: (11)
- Pale skin
- Shortness of breath
- Chest pain
- Frequent infections
- Dizziness or light-headedness
- Cold hands and feet
- Swelling or soreness of your tongue
- Cracks around your mouth
- Brittle nails
- Fast heartbeat
- Poor appetite
- Restless legs syndrome
- Enlarged spleen
- Cravings for nonfood items, such as ice, dirt, paint, or starch
If you’re mildly anemic, your doctor may recommend a diet filled with iron-rich foods. The foods with the highest iron content are:
- Meat, especially beef and liver
- Poultry — chicken livers are packed with iron
- Fish and shellfish, especially oysters
- Leafy greens, like kale, spinach, and broccoli
- Beans and peas
- Iron-enriched breads, pastas, and cereals
Take note that iron from vegetable sources is less readily absorbed than iron from meat, poultry, or seafood.
Anemia of Chronic Inflammation or Disease
Anemia of chronic disease is also sometimes called anemia of chronic inflammation or anemia of inflammation.
Anemia of inflammation and chronic disease is considered the second most common form of anemia after iron-deficiency anemia. (12) But the exact incidence of chronic disease anemia is not known, possibly because it’s underreported and often goes unrecognized.
This type of anemia occurs when a long-term medical condition affects your body’s ability to produce healthy red blood cells. Underlying conditions can vary and may include chronic illnesses such as cancer, infections, kidney disease and autoimmune and inflammatory diseases like rheumatoid arthritis or lupus. Most often, the chronic disease prevents your body from effectively using iron to create new red blood cells, even if there are normal or high levels of iron stored in the body. Treatment for certain diseases can also affect red blood cell production. (12,13)
The following chronic conditions can result in anemia of chronic disease: (13)
Inflammatory diseases Conditions that produce an inflammatory response in the body can cause anemia of chronic disease for several reasons:
- The inflammatory response can produce cytokines, a protein that protects the body against infection and interferes with iron processing and red blood cell production.
- Inflammation can cause internal bleeding that leads to a decrease in red blood cell count.
- Inflammation of the gastrointestinal system can interfere with the body’s ability to absorb iron from food.
Types of inflammatory disease known to cause anemia of chronic disease include:
- Rheumatoid arthritis
- Ulcerative colitis
- Crohn’s disease
- Inflammatory bowel disease
- Degenerative joint disease
Infectious diseases People who have infectious diseases can wind up with anemia of chronic disease if their immune system’s response to the infection interferes with red blood cell production.
As with inflammatory diseases, infectious diseases can cause the immune system to release cytokines, which can interfere with the body’s ability to use iron to create red blood cells. Cytokines also can block the production and function of erythropoietin, a hormone produced by the kidneys that prompts a person’s bone marrow to produce red blood cells.
Infectious diseases known to lead to anemia of chronic disease include:
- Endocarditis (heart infection)
- Osteomyelitis (bone infection)
Kidney failure People with kidney disease can develop anemia of chronic disease if the disease interferes with the kidneys’ production of erythropoietin. Diseased kidneys also can cause the body to absorb less iron and folate, nutrients necessary to the creation of red blood cells.
People with kidney failure also might experience iron deficiency as a result of blood loss that occurs during hemodialysis.
Certain types of cancer can prompt the release of inflammatory cytokines, which interfere with erythropoietin production and creation of red blood cells by the bone marrow. These cancers include:
- Hodgkin disease
- Non-Hodgkin lymphoma
- Lung cancer
- Breast cancer
Cancer also can harm red blood cell production if it invades the bone marrow. Moreover, cancer treatments like chemotherapy and radiation therapy can lead to anemia of chronic disease if they damage the bone marrow.
Pernicious anemia occurs when your body lacks vitamin B12, which is needed to make healthy red blood cells and to keep the nervous system working properly.
If you have pernicious anemia, your body can’t absorb enough vitamin B12 from food because it lacks a protein in the stomach called intrinsic factor. If you lack intrinsic factor, there is nothing you can do to prevent pernicious anemia caused by this.
Pernicious anemia can run in families, so having family members with the condition puts you at risk.
In rare cases, pernicious anemia occurs simply because you’re not eating enough B12. In these cases, eating foods high in B12 can help the condition. Such foods include: (14)
- Beef, liver, poultry, and fish
- Eggs and dairy products
- Soy-based drinks and veggie burgers
- Breakfast cereals with added vitamin B12
B12 deficiency can also be caused by other factors and conditions, such as infections, surgery, medicines, and diet, and in these cases, it may also be referred to as pernicious anemia.
Diseases such as Crohn’s and celiac can also interfere with B12 absorption.
With all forms of anemia, tiredness or fatigue is the most common symptom because of low red blood cell count. Shortness of breath, dizziness, headache, coldness in your hands and feet, pale or yellowish skin, and chest pain are other signs.
When you have low red blood cells, your heart has to work harder to move oxygen-rich blood through your body. When this occurs, you can experience irregular heartbeat, enlarged heart, or even heart failure.
If your doctor suspects you may have pernicious anemia, he or she can confirm it with blood tests. Bone marrow tests can also detect this type of anemia because when pernicious anemia is present, bone marrow cells that turn into blood cells are larger than normal. (14)
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