An Overview of Anemia

Table of Contents
View All
Table of Contents

Anemia is a condition in which, depending on the type, your red blood cell (RBC) count is lower than normal or there is a problem with the hemoglobin protein inside those cells. Hemoglobin is responsible for carrying oxygen to your tissues, so anemia can make you feel weak and tired. There are a variety of causes, from blood loss to deficiencies, and which type of anemia applies to you will determine the treatment you need.

symptoms of anemia
Verywell / Theresa Chiechi


If the anemia is mild, you may not experience any symptoms. As anemia worsens, symptoms may appear or become more pronounced. These may include:

  • Fatigue or tiredness
  • Weakness
  • A pale appearance to the skin
  • Dizziness or lightheadedness
  • Rapid heartbeat, known as tachycardia
  • Shortness of breath
  • Jaundice (some types of anemia cause yellowing of the skin)

Types and Causes

The different types of anemia can be categorized by the three basic causes of the condition: reduced production of red blood cells, blood loss, and increased destruction of red blood cells (hemolysis).

Anemias caused by reduced RBC production include:

  • Iron deficiency anemia: Due to decreased ability to absorb iron, or from chronic blood loss that depletes iron stores.
  • Vitamin deficiency anemias: Caused by inadequate intake of folate, B-12, or vitamin C; a type called pernicious anemia results from an inability to absorb vitamin B-12.
  • Anemia of inflammation: Due to chronic diseases such as kidney disease, leukemia and other blood cancers, lupus, HIV, and rheumatoid arthritis.
  • Chemotherapy-induced anemia (temporary as stem cells work to resume RBC production)
  • Aplastic anemia: A result of bone marrow failure

Types of anemia related to blood loss are:

  • Acute blood loss anemia: Seen in trauma, surgery, or acute bleeding from ulcers.
  • Chronic blood loss anemia: Can be caused by heavy menstrual periods (menorrhagia) or conditions that cause gastrointestinal tract bleeding, such as colon cancer or inflammatory bowel disease. Note: Chronic blood loss can also lead to iron deficiency.

And finally, increased destruction of red blood cells is behind these types of anemia:

  • Inherited anemias: These alter the structure of hemoglobin or the red blood cell, making them more fragile or short-lived. They include sickle cell disease, thalassemia, glucose-6-phosphate dehydrogenase (G6PD) deficiency, pyruvate kinase deficiency, hereditary elliptocytosis, and hereditary spherocytosis.
  • Alloimmune hemolytic anemia: This is due to exposure to an incompatible blood type through a transfusion reaction or in pregnancy when the mother is Rh-negative and the fetus is Rh-positive.
  • Autoimmune hemolytic anemia: This is a condition in which your immune system gets confused and inappropriately attacks (and destroys) your red blood cells.
  • Drug-induced hemolytic anemia: You might develop drug-induced hemolytic anemia after taking a medication, especially an antibiotic. It is due to an immune reaction.
  • Mechanical hemolytic anemias: These are due to physical damage to the red blood cells. The damage can come from a medical device, high blood pressure, or even strenuous activity.
  • Paroxysmal nocturnal hemoglobinuria: If you have paroxysmal nocturnal hemoglobinuria, your body destroys your red blood cells quicker and you also make fewer of every type of blood cell. Blood clots in veins are another feature of this syndrome.


Anemia is initially diagnosed with a complete blood count (CBC), a commonly performed blood test. Sometimes this test is run because you are having symptoms of anemia; sometimes anemia is identified incidentally when a CBC is drawn for routine annual labs.

Your healthcare provider will be looking for a decrease in hematocrit or hemoglobin.

Test Results Indicating Anemia

In adults, anemia is indicated if levels are below the following normal ranges:

  • Hemoglobin: 14 to 17.4 grams per decilitre (g/dL) in men; 12.3 to 15.3 g/dL in women
  • Hematocrit: 40% to 52% for men; 35% to 47% for women

After diagnosing you with anemia, your physician may refer you to a hematologist, a doctor who specializes in blood disorders, to determine the cause of your anemia.

Other information gleaned from the CBC that can help differentiate one type of anemia from another will be considered, including red blood cell size (mean corpuscular volume), variation in size (red cell distribution width), and concentration of hemoglobin in the red blood cells (mean corpuscular hemoglobin concentration).

You will likely also undergo more blood work to confirm the cause of your anemia, including, a reticulocyte count (a measure of "baby" red blood cells just released by bone marrow) and a blood smear, which allows a physician to look at the red blood cells under the microscope


Just like the causes of anemia, there are numerous treatments for it. The treatment you require depends on the cause of your anemia. Treatments include:

  • Supplements like iron, folate, or vitamin B12
  • Blood transfusions
  • Chemotherapy (if the anemia is caused by cancer)
  • Erythropoietin injections (for people with anemia caused by kidney disease)
  • Steroids (for autoimmune hemolytic anemia)
  • Splenectomy (surgical removal of the spleen) for some forms of hemolytic anemia

Some forms of anemia do not have any specific treatment and may be lifelong. If the anemia is caused by a chronic illness, treating the underlying condition might improve your anemia.

A Word From Verywell

After learning you have anemia, it's natural to ask: What caused it? What do I do about it? It is important to recognize that some anemias are easy to diagnose and treat, and others can take a long time. Don't ignore how you are feeling or resign yourself to your symptoms. Be open and honest with your physician and work together to feel your best.

6 Sources
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Turner J, Badireddy M. Anemia. StatPearls Publishing.

  2. Miller JL. Iron deficiency anemia: a common and curable diseaseCold Spring Harb Perspect Med. 2013;3(7):10.1101/cshperspect.a011866 a011866. doi:10.1101/cshperspect.a011866

  3. Ishii K, Young NS. Anemia of Central OriginSemin Hematol. 2015;52(4):321–338. doi:10.1053/j.seminhematol.2015.07.002

  4. Packman CH. The Clinical Pictures of Autoimmune Hemolytic AnemiaTransfus Med Hemother. 2015;42(5):317–324. doi:10.1159/000440656

  5. Cascio MJ, Deloughery TG. Anemia: Evaluation and Diagnostic Tests. Med Clin North Am. 2017;101(2):263-284. doi:10.1016/j.mcna.2016.09.003

  6. Johnson-Wimbley TD, Graham DY. Diagnosis and management of iron deficiency anemia in the 21st centuryTherap Adv Gastroenterol. 2011;4(3):177–184. doi:10.1177/1756283X11398736

Additional Reading
  • Sandoval C. Approach to the child with anemia. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA,

  • Schrier SL. Approach to the adult patient with anemia. In: UpToDate, Post TW (Ed), UpToDate, Waltham, MA.

  • Marks PW. Approach to Anemia in the Adult and Child. In: Hoffman R, Benz Jr. EJ, Silberstein LE, Heslop HE, Weitz JI and Anatasi J eds. Hematology: Basic Principles and Practice. 6th Ed. Philadelphia, PA: Elsevier Saunders; 2013.

By Amber Yates, MD
Amber Yates, MD, is a board-certified pediatric hematologist and a practicing physician at Baylor College of Medicine.