Anemia is a condition that develops when your red blood cell count or hemoglobin levels are below normal. The condition 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.
Types of Anemia
There are different types of anemia, including:
Iron-deficiency anemia is the most common type of anemia and occurs when your blood doesn’t have enough iron to produce healthy red blood cells and hemoglobin.
This type of anemia, which is the most common and widespread nutritional disorder in the world, largely contributes to the fact that more than 30 percent of the world’s population is anemic.
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.
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.
Aplastic anemia can strike people of any age, race, or gender, but it’s more common among children, teenagers, and older adults. It is also more likely to occur in people of Asian heritage.
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 how 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 and damage.
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.
Pernicious anemia refers to a vitamin B12 deficiency caused by autoantibodies that interfere with vitamin B12 absorption by targeting intrinsic factor (IF), gastric parietal cells, or both. This type of anemia occurs when your body cannot absorb vitamin B12, which is needed to make healthy red blood cells and to keep the nervous system working properly.
The condition can run in families and is an autoimmune condition. B12 deficiency from low intake can also mimic pernicious anemia as they both result in anemia from reduced available B12 for red blood cell creation.
With proper treatment, people who have pernicious anemia can recover, feel well, and live normal lives.
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.
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 illnesses such as cancer, infections, 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.
Signs and Symptoms of Anemia
Different types of anemia may have some different symptoms, but there is also some overlap. The most common symptom of all anemias is weakness. Here are some other symptoms:
Iron-deficiency anemia symptoms may be mild, but as the condition advances, they can get worse and include:
Extreme fatigue
Weakness
Pale skin
Chest pain, rapid heartbeat, or shortness of breath
Aplastic anemia symptoms may be severe from the start or gradually worsen over time. They include:
Bleeding or bruising easily
Heavy menstrual bleeding
Shortness of breath
Fatigue
Frequent infections
Sickle cell anemia symptoms can develop in some children earlier than others and typically start after the fifth or sixth months of life. Common signs and symptoms include:
Yellowish skin, known as jaundice
Yellowish whites of the eyes, known as icterus
Fatigue or fussiness
Painful swelling of the hands and feet
Frequent infections, especially pneumonia
Fatigue and weakness
Episodes of pain, called sickle cell crises, which occur when sickled red blood cells block blood flow to the limbs and organs
Pernicious anemia may cause symptoms similar to other anemias as well as symptoms related to a vitamin B12 deficiency:
Tingling and numbness in hands and feet
Muscle weakness
Loss of reflexes
Loss of balance
Trouble walking
Weakened bones, leading to hip fractures
Neurological problems, such as confusion, dementia, depression, and memory loss
Nausea, vomiting, heartburn, abdominal bloating and gas, constipation or diarrhea, loss of appetite, and weight loss
Enlarged liver
Smooth, thick, red tongue
Infants who have B12 deficiency may show the following signs and symptoms:
Poor reflexes or unusual movements like face tremors
Difficulty feeding due to tongue and throat problems
Irritability
Permanent growth problems if left untreated
Anemia of chronic disease may cause similar signs and symptoms to other anemias, such as:
Fatigue
Pale skin
Light-headedness
Shortness of breath
Rapid heartbeat
Irritability
Chest pain
Causes and Risk Factors for 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. But the vitamin B12, folate, and other nutrients that we get from food are needed to produce hemoglobin and red blood cells.
If you lack these vitamins and nutrients in your diet or cannot absorb them, you can become anemic.
In addition to not producing enough red blood cells, you can also become anemic if your body destroys its red blood cells prematurely or if your body loses red blood cells through bleeding more quickly than they can be replaced.
Each type of anemia is caused by something different, and each can range from mild to severe.
Iron-deficiency anemia develops when your body doesn’t have enough iron because of blood loss, when you consume inadequate amounts of iron, or when you have a medical condition that affects your body’s ability to absorb iron from the gastrointestinal tract.
Aplastic anemia is thought to be either acquired or inherited, though the exact cause is not known.
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 herpesvirus)
Autoimmune disorders such as lupus and rheumatoid arthritis
Causes of inherited aplastic anemia, which is rare and develops from genes that are passed down from parent to child, include:
Fanconi anemia
Shwachman–Diamond syndrome
Ataxia-pancytopenia syndrome
Over time, severe heart issues may develop, such as arrhythmia (irregular heartbeat), 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.
Sickle cell anemia occurs when a person inherits 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 cell trait.
People with sickle cell 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 who have ancestors from sub-Saharan Africa; regions in the Western Hemisphere (South America, the Caribbean, and Central America); Saudi Arabia; India; and Mediterranean countries, such as Turkey, Greece, and Italy.
In the United States, the condition affects more than 100,000 people, and mainly affects Black Americans; 1 out of 365 Black American babies is born with sickle cell anemia.
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 the 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 over 1 percent of the population.
Pernicious anemia occurs when the body can’t absorb enough vitamin B12 from food because it lacks a protein in the stomach called intrinsic factor, caused by autoantibodies to intrinsic factor or parietal cells. 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.
Since people with pernicious anemia cannot effectively absorb B12, they must receive supplemental B12 through injections, followed by very high oral doses once bodily B12 stores are replenished.
Another form of B12-related anemia, called megaloblastic anemia, can occur if you’re not eating enough B12. In these cases, eating foods high in B12 can help the condition. Such foods include:
Beef, liver, poultry, and fish
Eggs and dairy products
Fortified vegan milk substitutes
Breakfast cereals with added vitamin B12
B12 deficiency can also be caused by other factors and conditions, such as infections, surgery, and medicines.
Diseases such as Crohn’s and celiac disease can also interfere with B12 absorption.
Anemia of chronic disease can be caused by the following chronic conditions:
Autoimmune diseases, such as rheumatoid arthritis or lupus
Cancer
Infectious diseases, such as HIV/AIDS and tuberculosis
Chronic kidney disease (as well as dialysis, which is used to treat it)
Inflammatory bowel disease, such as Crohn’s disease or ulcerative colitis
Other chronic diseases that involve inflammation, such as diabetes and heart failure
How Is Anemia Diagnosed?
To determine if you have anemia, your doctor will most likely talk to you about your medical and family history, give you a physical exam, and perform the following tests:
Complete Blood Count (CBC) A CBC will reveal the number of blood cells in a blood sample. To determine if you have anemia, your doctor will look at your blood’s number of red blood cells (hematocrit) and hemoglobin. Doctors may have different target numbers, but normal adult hematocrit values tend to range from 40 to 52 percent for men and 35 to 47 percent for women. Target adult hemoglobin values are generally 14 to 18 grams per deciliter (g/dL) for men and 12 to 16 g/dL for women.
Peripheral Smear A peripheral smear looks at the size and shape of red blood cells.
Bone Marrow Sample Your doctor may recommend an invasive test to gather a sample of your bone marrow if you are diagnosed with anemia. This can help determine the cause.
Prognosis of Anemia
The prognosis of anemia depends on its type.
Iron-Deficiency Anemia
Most people with iron-deficiency anemia will fully recover. But if the underlying condition is not corrected, and chronic iron deficiency persists until the red cell count and hemoglobin levels get extremely low, it can be fatal.
Aplastic Anemia
While prognosis varies from person to person, the condition can be short-lived for those who develop aplastic anemia because of medications, pregnancy, low-dose radiation, or infectious mononucleosis. The condition can be life-threatening if it’s severe and lasts a long time or if treatments are not effective.
For those who do not recover, they may receive a bone marrow transplant from a sibling or other matched donor; their prognosis is better than for those who receive a transplant from a donor unrelated to them. And the prognosis is increasingly reported to be favorable.
For older patients with acquired aplastic anemia, when immunosuppressive therapy is the only option, about 50 percent of people will respond well to it.
People with aplastic anemia are at higher than average risk of developing leukemia.
Sickle Cell Anemia
While there is no cure for sickle cell anemia, improved treatments for pain management and treating symptoms provide a better outlook for people with the disease. Treatments include oral medications (such as hydroxyurea), over-the-counter drugs, and blood transfusions. Some people with sickle cell disease are candidates for potentially curative procedures including bone marrow transplants or gene therapies.
Pernicious Anemia
Pernicious anemia, once it manifests, will require treatment for the duration of one’s life, yet treatment is well tolerated and the disorder should not cause significant hardship.
Some studies have shown that having pernicious anemia increases the chances of developing stomach cancer.
Anemia of Chronic Disease
If the underlying condition that is causing anemia of chronic disease gets treated, the condition can resolve as a result.
Duration of Anemia
The duration of anemia depends on the type.
Iron-Deficiency Anemia
Iron supplements (prescribed by your physician or hematologist) taken orally can work within 3 to 10 days to increase the body’s production of red blood cells; however, it typically takes months to bring iron levels back to normal. Additionally, if the source of the iron-deficiency anemia is an underlying condition, duration would depend on if and how that is addressed.
Aplastic Anemia
When aplastic anemia is caused by radiation, chemotherapy, and other drugs, the condition tends to subside once treatments stop.
For women who develop aplastic anemia when pregnant, the condition usually improves once they’re no longer pregnant.
Sickle Cell Anemia
Having sickle cell anemia is a lifelong condition. A bone marrow transplant or gene therapy are potential cures.
Pernicious Anemia
While pernicious anemia is a lifelong condition, treatment can help people feel well and live normal lives. In most cases, early diagnosis and treatment can help reverse complications of pernicious anemia, such as nerve damage.
Anemia of Chronic Disease
When the underlying condition that is causing anemia of chronic disease is treated, the condition tends to go away.
Treatments and Medication Options for Anemia
Each type of anemia will require a different type of treatment, which would depend on the specifics of your diagnosis and severity of your condition:
Growth factors, both naturally occurring and man-made, are hormones that stimulate bone marrow to make blood cells to treat aplastic anemia. Immunosuppressive drug therapy and bone marrow transplants are another option.
Iron-deficiency anemia is treated with oral iron supplements and, in some cases, intravenous (IV) iron therapy. Treating the underlying cause is also important.
Treatments for sickle cell anemia include oral medication and blood transfusions. A bone marrow transplant or stem cell transplant may cure sickle cell anemia. Gene therapies are another potential cure.
B12 supplements or shots may help pernicious anemia.
When low iron is caused by an inadequate diet lacking iron-rich foods, a focus on high-iron foods, such as meat, poultry, fish, beans, tofu, dried fruits, dark green leafy vegetables, and iron-fortified foods like breads and cereals, can help.
Preventing Anemia
In some instances, iron-deficiency anemia can be prevented with the following methods:
Treating Blood Loss For those with heavy menstrual periods or stomach issues, such as frequent diarrhea or blood in the stool, addressing the root imbalances leading to blood loss can help prevent anemia.
Consuming Foods With Iron Eating foods with high levels of iron, like lean meat, chicken, dark leafy vegetables, and beans, can increase iron levels.
Ensuring Enough Vitamin C Drinks and foods with vitamin C, like orange juice, strawberries, and broccoli, can help the body absorb iron.
Following a Balanced Diet Balanced diets can ensure enough iron is being consumed.
Limiting Coffee or Tea With Meals If you drink coffee and tea with meals, they can make it difficult for your body to absorb iron.
Taking Caution With Calcium Pills Because calcium can affect how your body absorbs iron, ask your doctor what the best approach is for getting both enough calcium and enough iron.
While there’s no known prevention for aplastic anemia, staying clear of insecticides, herbicides, organic solvents, paint removers, and other toxic chemicals may lower your risk.
While pernicious anemia caused by a lack of intrinsic factor is not preventable, those who develop the disease because they lack B12 in their diet can potentially reduce the impact by eating foods high in B12, such as beef, eggs, fortified cereal, and other fortified foods. But, ultimately, they are likely to need high-dose B12 supplementation or injections under their doctors’ guidance.
Complications of Anemia
When anemia is not treated, it can cause complications, including:
Extreme fatigue resulting in the inability to function
Pregnancy complications, including premature birth
Heart problems, such as irregular heartbeat, enlarged heart, and heart failure
Death
Research and Statistics: Who Has Anemia?
As of 2024, the overall prevalence of anemia in people aged 2 years and older was 9.3 percent. The prevalence was higher in females (13.0 percent) than in males (5.5 percent); it was also higher in Black people (22 percent) compared with Asians (11.8 percent), Hispanics (10.9 percent), and whites (6.1 percent).
The Takeaway
Anemia is a condition that develops when your red blood cell count or hemoglobin levels are below normal. There are several different types of anemia; each type has its own causes and prognosis.
Depending on the type of anemia, treatments can include pills or injections, dietary changes, blood transfusions, and bone marrow transplants.
If you have symptoms of anemia, such as fatigue, weakness, or paleness, contact your doctor for a proper diagnosis.
