Iron Deficiency Anemia: Symptoms, Tests, Treatment

Introduction

Iron deficiency anemia occurs when the body lacks enough usable iron to make hemoglobin ^[1,3]. Hemoglobin is the protein in red blood cells that carries oxygen ^[6]. Without enough hemoglobin, the blood carries less oxygen through the body ^[3].

Iron deficiency can develop without clear warning signs ^[1,3]. The body first uses iron stored in the liver, muscles, spleen, and bone marrow ^[3]. Symptoms may appear after these stores become low ^[3].

Understanding iron deficiency anemia symptoms, causes, testing and treatment can help you seek timely care. Blood tests can confirm anemia and show whether iron stores are low ^[5,8]. A doctor should also find out why the iron became low ^[7,8].

Blood loss or a digestive disorder may be the cause ^[7,8]. Treating the cause is just as important as replacing iron ^[6,7].

Overview: What Is Iron Deficiency Anemia?

Iron deficiency anemia is the most common form of anemia ^[1,6]. It develops when available iron cannot support normal red blood cell production ^[1,3].

How iron supports hemoglobin and oxygen delivery

Bone marrow needs iron to make hemoglobin ^[6]. Without enough iron, the marrow cannot make enough hemoglobin-rich red blood cells ^[3,6].

The red blood cells may become smaller and paler than normal ^[3,5]. They also contain less hemoglobin ^[3]. As a result, the blood delivers less oxygen to the body ^[3].

Low oxygen delivery can cause fatigue and weakness ^[1,3]. It can also reduce a person’s ability to work or exercise ^[3].

Iron deficiency versus iron deficiency anemia

Iron deficiency and iron deficiency anemia are not the same condition. Iron deficiency means the body has low iron stores or little usable iron ^[4]. Iron deficiency anemia occurs when the lack of iron affects hemoglobin and red blood cell production ^[1,3].

A person can have iron deficiency without anemia ^[4]. In the early stage, the body draws iron from its stored supply ^[3]. This stage may not cause obvious symptoms ^[3].

A ferritin test can help assess stored iron ^[5]. Low ferritin levels often support a diagnosis of iron deficiency ^[5,8].

Inflammation can also cause functional iron deficiency ^[4]. In this condition, the body has iron but cannot use it normally ^[4]. Certain cells hold the iron instead of releasing it for use ^[4].

Who has a higher risk of low iron?

Some groups have greater iron needs or a higher chance of blood loss. Others may not eat or absorb enough iron.

Groups at increased risk include:

• Infants and young children ^[3]
• Pregnant people ^[3]
• People younger than 50 who menstruate ^[3]
• People who have heavy menstrual bleeding ^[7,8]
• Frequent blood donors ^[1]
• People who avoid meat, poultry, and seafood ^[3]
• People with digestive diseases that affect iron absorption ^[3]
• People with long-term inflammation ^[8]

A risk factor does not prove that a person has anemia. Doctors review symptoms, health history, and blood test results together ^[5,8].

Iron Deficiency Anemia Symptoms and Warning Signs

Iron deficiency symptoms often develop slowly ^[6,7]. Mild or moderate anemia may cause no noticeable problems ^[1]. Symptoms tend to become worse as iron and hemoglobin fall ^[7].

Common early and progressive symptoms

Fatigue is a common symptom of iron deficiency anemia ^[1,6]. A person may feel tired even after getting enough rest. Work, exercise, or daily tasks may become more difficult ^[3].

Other iron deficiency symptoms may include:

• Weakness or lack of energy ^[3,7]
• Pale skin ^[1,7]
• Dizziness or lightheadedness ^[1]
• Headaches ^[7]
• Cold hands and feet ^[1,6]
• Poor focus or memory problems ^[3]
• Shortness of breath ^[1,6]
• Chest pain ^[1,7]
• A fast or racing heartbeat ^[6,7]
• Lower exercise ability ^[3]

These symptoms can occur with several health conditions. Symptoms alone cannot confirm iron deficiency anemia. A healthcare professional can use blood tests to make the diagnosis ^[5].

Less common signs in adults and children

Some people develop pica, which means craving substances that are not food ^[7]. These cravings can include ice, dirt, or starch ^[7].

Other possible signs include:

• A sore or inflamed tongue ^[7]
• Brittle nails ^[7]
• Poor appetite in infants and children ^[7]
• Trouble learning in infants and children ^[3]
• Trouble controlling body temperature ^[3]
• Less ability to fight germs and infections ^[3]

Infants and children with iron deficiency anemia may develop learning problems ^[3]. Parents should discuss changes in learning, eating, or energy with a healthcare professional.

When symptoms may be serious

More serious anemia may cause chest pain or shortness of breath ^[1]. It may also cause dizziness or a racing heartbeat ^[1,6,7].

New or severe symptoms need prompt medical review. This is especially important when chest pain or serious breathing problems occur.

Ongoing digestive blood loss can cause iron deficiency anemia ^[7,8]. A person with suspected blood loss should not rely only on iron supplements. A medical evaluation can help find and treat the source ^[7,8].

Causes of Iron Deficiency Anemia

The main causes include blood loss, low intake, greater needs, and poor absorption ^[4]. Some people have more than one cause.

Blood loss from periods or internal bleeding

Ongoing blood loss can slowly drain the body’s iron supply ^[7]. Heavy menstrual bleeding is a common cause in people who have periods ^[7,8].

Blood can also be lost through the stomach or intestines ^[7,8]. Ulcers and other digestive diseases may cause this type of blood loss ^[7]. Some pain relievers can also contribute to digestive bleeding ^[7].

Frequent blood donation can reduce available iron ^[1]. Surgery and bleeding from other parts of the body may also contribute ^[1].

Men and postmenopausal women may lack a clear reason for iron deficiency anemia. These patients may need tests for digestive blood loss or disease ^[8]. Other patients without an obvious cause may need the same type of evaluation ^[8].

Iron replacement alone may not stop continued blood loss. Doctors should investigate the cause instead of treating only the low iron ^[7,8].

Low iron intake and increased iron needs

A diet with too little iron can drain stored iron over time ^[3,4]. People who avoid meat, poultry, and seafood may have a higher risk ^[3].

Iron needs rise during pregnancy and times of fast growth ^[3]. Infants, children, teens, and pregnant people may need more iron ^[3]. Deficiency can develop when iron intake does not meet these needs ^[3].

Iron-rich foods include:

• Meat
• Poultry
• Seafood
• Beans and lentils
• Spinach and peas
• Nuts
• Foods with added iron, such as some breads and cereals ^[3]

The body absorbs iron from animal foods more easily than iron from plant foods ^[3]. People who avoid animal foods may need careful meal planning ^[3].

Poor absorption and digestive conditions

Some digestive disorders prevent the body from absorbing enough iron ^[3]. A person can become deficient even when food provides enough iron ^[3,4].

Celiac disease is one possible cause ^[8]. This disease can damage the small intestine and affect nutrient absorption. Testing for celiac disease may be part of an anemia evaluation ^[8].

Other digestive diseases may also reduce iron absorption ^[3]. A past digestive problem can therefore be important when a doctor reviews the possible causes.

Treatment may not work well if poor absorption continues. Iron deficiency may also return when the main cause remains untreated ^[7,8].

Testing and Diagnosis

An iron deficiency anemia test usually involves several blood measurements. Doctors also review symptoms, diet, medical history, and possible blood loss ^[5,8].

Complete blood count and red blood cell findings

A complete blood count is often called a CBC. It measures blood cells and several related values.

The CBC includes hemoglobin and hematocrit ^[5]. Hematocrit is the percentage of blood made up of red blood cells ^[5].

Low hemoglobin supports a diagnosis of anemia ^[5]. Normal ranges vary based on age and sex ^[5]. Hematocrit may also be below the expected range ^[5].

Iron deficiency anemia often causes small, pale red blood cells ^[4,5]. Doctors call small cells “microcytic” ^[4]. They call pale cells “hypochromic” because the cells contain less hemoglobin ^[4,5].

Small or pale cells can have other causes ^[4]. These causes include thalassemia, inflammation, and lead exposure ^[4].

Thalassemia is an inherited blood disorder that affects hemoglobin. Doctors may order more tests when the CBC does not clearly show the cause. These may include a reticulocyte count, cell review, or lead test ^[4].

Ferritin, transferrin saturation, and other iron tests

Ferritin is a protein that stores iron ^[5]. A ferritin blood test helps estimate the body’s iron reserves ^[5].

Low ferritin generally supports iron deficiency ^[5,8]. However, inflammation can raise ferritin ^[8]. Diagnostic limits and test meaning therefore depend on the person’s health setting ^[8].

One current primary care guideline uses a ferritin level below 45 ng/mL in adults without inflammation ^[8]. This result supports iron deficiency under that guideline ^[8].

A ferritin result from 46 through 99 ng/mL may need another test ^[8]. Iron deficiency is supported when transferrin saturation is also below 20% ^[8]. Results require different review when inflammation is present ^[8].

Transferrin is a protein that moves iron through the blood. Transferrin saturation estimates how much of that protein is carrying iron. It can help when ferritin results are hard to understand ^[8].

No single result should be viewed alone. Doctors interpret low ferritin levels with the CBC, symptoms, and health history ^[5,8].

Tests used to find the underlying cause

Further testing depends on age, sex, symptoms, periods, diet, and health history ^[8]. A doctor may ask about heavy periods and blood donation ^[1,7,8]. Questions may also cover medicines, eating patterns, and digestive symptoms ^[1,7,8].

Some adults may need testing for celiac disease ^[8]. Testing for Helicobacter pylori may also be advised ^[8]. This germ can affect the stomach.

Digestive tests may include an upper endoscopy or colonoscopy ^[8]. These tests let doctors examine parts of the digestive tract. They can help look for disease or a source of blood loss ^[8].

Men and postmenopausal women usually need close review for a digestive cause ^[8]. Younger patients may have an expected cause, such as heavy periods ^[8]. In those cases, doctors may treat the bleeding and replace iron ^[8].

Other tests may be needed when the results are not typical. Other possible causes include inflammation, thalassemia, lead exposure, or another blood disorder ^[4].

Treatment, Recovery, and Prevention

Iron deficiency anemia treatment has two main goals. The first is to replace missing iron ^[6,7]. The second is to find and treat the cause ^[6,7].

Iron deficiency may return when bleeding continues ^[7,8]. It may also return when poor absorption remains untreated ^[7,8].

Oral iron supplements and food sources

Oral iron is often the first treatment choice ^[2,8]. “Oral” means that the iron is taken by mouth.

No single product or schedule works best for everyone ^[2]. A healthcare professional should choose the product, dose, and treatment length.

Side effects and absorption can affect the treatment plan ^[2]. The level of iron loss may also affect the choice ^[2].

Iron supplements for anemia can cause stomach or bowel side effects ^[3]. Too much iron can be harmful ^[3]. People should not take iron long term without medical advice.

Iron supplements must be kept away from children ^[3]. An accidental overdose can be dangerous ^[3].

Iron-rich foods can support treatment and help prevent future deficiency ^[3]. Choices include meat, seafood, poultry, beans, lentils, nuts, and leafy vegetables ^[3]. Foods with added iron can also help ^[3].

Food changes may not be enough after anemia develops ^[7]. A doctor can decide whether iron supplements are also needed.

When intravenous iron may be considered

Intravenous iron enters the body through a vein. It may help when oral iron cannot be used or does not work well ^[2,6].

Intravenous iron may be appropriate for poor absorption ^[2]. It may also help when oral iron causes side effects ^[2]. Other reasons include an inadequate response or a need for faster replacement ^[2,6].

Ongoing iron loss can also affect the treatment choice ^[2]. The decision should reflect the patient’s needs and treatment goals ^[2].

Monitoring response and preventing recurrence

Follow-up blood tests help show whether treatment is working ^[5,8]. A doctor may repeat the CBC, ferritin, or other iron tests ^[5,8].

A poor response can have several causes. These include missed treatment, continued bleeding, poor absorption, or a different diagnosis ^[2,4]. More evaluation may be needed instead of simply taking more iron.

Prevention depends on what caused the deficiency. It may involve treating heavy menstrual bleeding or digestive disease ^[7,8]. Changes to diet or blood donation may also help ^[1,3].

People with an ongoing risk may need more blood tests. A healthcare professional can decide how often testing is needed.

When to See a Doctor

Arrange a medical visit for lasting fatigue, weakness, pale skin, or dizziness ^[1,3,6]. Poor focus, shortness of breath, or a racing heartbeat also need medical review ^[1,3,6].

Seek advice if you have heavy menstrual bleeding ^[7,8]. You should also seek care when you suspect ongoing blood loss ^[7,8].

Do not start long-term iron treatment based only on fatigue. Many conditions can cause similar symptoms ^[4]. Too much iron can also cause harm ^[3].

Blood tests can show whether anemia is present ^[5]. Ferritin and other iron tests can help confirm iron deficiency ^[5,8].

Prompt care is important for chest pain or severe shortness of breath ^[1,7]. Fainting or a very fast heartbeat also needs quick medical review ^[6,7]. These symptoms may occur with more serious anemia ^[1,6,7].

Conclusion

Understanding iron deficiency anemia symptoms, causes, testing and treatment can support earlier care. Iron deficiency can begin before a person develops anemia ^[4]. Mild iron deficiency anemia may cause no clear symptoms ^[1,3].

Diagnosis often includes a CBC and tests of iron stores ^[5,8]. Low ferritin levels usually support iron deficiency ^[5,8]. Inflammation can raise ferritin and make the result harder to interpret ^[8].

Effective treatment replaces iron and addresses the cause ^[6,7]. Oral iron is commonly the first choice ^[2,8]. Intravenous iron may help people with poor absorption, side effects, or a weak response ^[2,6].

Men, postmenopausal women, and others without a clear cause may need digestive testing ^[8]. This evaluation can help find hidden blood loss or disease ^[8].

Medical follow-up can show whether hemoglobin and iron stores are improving ^[5,8]. It also helps reduce the chance of missing continued blood loss or another cause ^[7,8].