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What Is Anemia?

Anemia is a blood disorder marked by a decreased amount of red blood cells (RBCs). People with anemia have insufficient hemoglobin, a protein in red blood cells that carries oxygen through the body.

Anemia is the most common blood disorder in Americans, and it can have far-reaching symptoms or none at all. Some of the most common symptoms include fatigue, shortness of breath, and headaches.

There are multiple types of anemia with diverse potential causes. Anemia is usually related to a failure to generate enough normal red blood cells, increased destruction of red blood cells, or blood loss. Anemia testing is essential to diagnosing anemia and identifying its underlying cause.

The Role of Anemia Testing

Routine blood testing, such as during a medical check-up, may reveal anemia in patients who have mild cases with few or no symptoms.

In people who have symptoms, diagnostic anemia testing can determine whether red blood cells are diminished. In-depth analysis of the blood often helps with finding the type and cause of anemia.

Because anemia is a blood disorder, most tests use a blood sample. However, doctors may need to check for different potential causes, which can involve other types of testing.

Types of Anemia Tests

The complete blood count (CBC) is an essential part of anemia testing. This test measures different types of cells in the blood. It is often used as part of a routine check-up and in diagnosing health problems, and it can reveal the presence of anemia.

The CBC analyzes the amount of various blood cells as well as a protein called hemoglobin in the blood. Other tests, described in the following tables, may be prescribed depending on your CBC results, symptoms, and health history.

Additional tests can help identify the type and cause of anemia, but most patients do not need extensive testing. Your doctor is in the best position to address which tests are most relevant in your situation.

Because anemia is a blood disorder, various tests, such as those in the table below, can be used to do an in-depth analysis of different components of the blood. Tests like a blood smear, white blood cell differential, and reticulocyte count can often help assess anemia after an abnormal CBC. Other listed blood tests may be warranted in more specific circumstances:

TESTS RELATED TO BLOOD CELL TYPES, COUNTS, AND FUNCTION
Test Name Test Sample What It Measures
Blood smear Blood The number, size, and type of different blood cells
Differential Blood The number of different types white blood cells
Reticulocyte count Blood The number of reticulocytes, which are newly formed red blood cells

In some types of anemia, red blood cells are destroyed faster than they can be replaced. The following tests may be used to measure an abnormal breakdown of red blood cells:

TESTS RELATED TO INCREASED DESTRUCTION OF RED BLOOD CELLS
Test Name Test Sample What It Measures
Hemoglobinopathy evaluation Blood The amount of different types of hemoglobin, a protein in red blood cells
Haptoglobin Blood A protein that can reflect destruction of red blood cells
Lactate dehydrogenase (LD) Blood An enzyme that can be a sign of tissue damage and red blood cell destruction
Osmotic fragility test Blood The vulnerability of red blood cells to breaking apart
G6PD Blood An enzyme that helps prevent red blood cells from breaking apart
Direct antiglobulin test Blood Whether red blood cells are being attacked by antibodies of the immune system

Anemia can occur because of unidentified blood loss. When this cause is suspected, tests such as those in the table below may look for signs of blood loss especially in the gastrointestinal system:

TESTS RELATED TO POTENTIAL BLOOD LOSS
Test Name Test Sample What It Measures
Fecal occult blood test (FOBT) Stool Traces of blood
Fecal immunochemical test (FIT) Stool Traces of protein from blood
H. pylori test Stool, breath, or biopsy Presence of a bacteria that can cause ulcers and gastrointestinal bleeding

Anemia can also occur alongside lowered platelets, which are the blood cells that help form blood clots and stop bleeding. Several tests can help measure blood coagulation:

TESTS RELATED TO BLOOD COAGULATION
Test Name Test Sample What It Measures
Partial thromboplastin time Blood Proteins involved in forming of blood clots
Thrombin time (TT) Blood Time required for typical processes of blood clot formation
Prothrombin time and international normalized ratio (PT/INR) Blood Proteins that influence blood clotting

Iron is necessary to create red blood cells, and a decreased amount of iron is the most common cause of anemia. Multiple tests can be employed to detect iron deficiency:

TESTS RELATED TO IRON DEFICIENCY
Test Name Test Sample What It Measures
Serum iron Blood Iron levels
Ferritin Blood A protein that reflects the amount of iron stored in cells
Transferrin and total iron-binding capacity (TIBC) Blood Proteins that bind to and help carry iron in the blood
Soluble transferrin receptor (sTfR) Blood Proteins that often correlate with iron levels in the blood

Your body needs certain vitamins to create red blood cells. Tests for nutritional deficiency may be ordered if your doctor considers this to be a possible cause of anemia in your case:

TESTS RELATED TO NUTRIENT DEFICIENCY
Test Name Test Sample What It Measures
Vitamin B12 and folic acid testing Blood Levels of vitamin B12 and folate (vitamin B9)
Methylmalonic acid (MMA) Blood or urine Levels of an acid that can reflect B12 deficiency
Homocysteine Blood or urine Levels of an amino acid that can reflect early signs of vitamin deficiency
Intrinsic factor antibody Blood A specific protein that can affect the body’s ability to absorb vitamin B12
Parietal cell antibody Blood A specific protein that can affect the body’s ability to absorb vitamin B12

 

Other medical conditions can trigger anemia. Tests may be used in order to check for underlying illnesses that negatively affect major organs and other bodily systems:

TESTS RELATED TO BODILY HEALTH AND ORGAN FUNCTION
Test Name Test Sample What It Measures
Comprehensive metabolic panel (CMP) Blood 14 different elements related to metabolism, kidney function, and liver function
Liver panel Blood Various proteins, enzymes, and other indicators of liver health
Kidney (renal) panel Blood Electrolytes, minerals, proteins, and other compounds that reflect kidney health
C-Reactive protein (CRP) Blood A protein related to inflammation in the body
Heavy metal testing Blood or urine Levels of potentially toxic heavy metals including lead, mercury, and arsenic that can affect the bone marrow
Abdominal sonogram N/A Provides ultrasound imaging of the abdominal organs

Some types of infections disrupt the body’s ability to maintain a healthy number of red blood cells. Your doctor may test for signs of one of these infections if this is believed to be a potential cause of your low red blood cell count:

TESTS RELATED TO POTENTIAL INFECTIONS
Test Name Test Sample What It Measures
HIV Blood or saliva Antigens or antibodies related to infection with HIV
Epstein-Barr Virus (EBV) Blood Antibodies to EBV
Cytomegalovirus (CMV) Blood, sputum, or other fluid Antibodies to CMV

Getting Tested for Anemia

Anemia testing usually takes place in a doctor’s office, laboratory, or hospital. Most tests for anemia involve a blood sample that is drawn from your arm using a needle or from a prick of the finger.

Anemia can be detected on routine blood work, or tests for anemia may be ordered after a person has symptoms consistent with anemia. People receiving treatment for anemia may have follow-up testing to monitor their response to treatment.

Anyone with symptoms of anemia or other concerns about this condition should talk with their doctor to determine which tests would be most appropriate in their case.

At-home anemia testing

At-home test kits are available that can analyze blood levels that are relevant to anemia:

  • Tests measuring hemoglobin, a protein found in red blood cells that may be deficient in anemia.
  • Tests measuring levels of the protein ferritin in the blood that may indicate iron deficiency.

These kits involve obtaining a drop of blood after pricking your fingertip.

At-home testing does not diagnose anemia and is not a substitute for either medical care or testing ordered by a doctor and conducted in a controlled laboratory.

Sources and Resources

The following resources provide information about the types, causes, symptoms, and treatment of anemia:

Sources

A.D.A.M. Medical Encyclopedia. Central sleep apnea. Updated February 26, 2021. Accessed March 19, 2021. https://medlineplus.gov/ency/article/000560.htm

American Academy of Family Physicians. Anemia. Updated March 10, 2021. Accessed March 19, 2021. https://familydoctor.org/condition/anemia/.

Freeman AM, Rai M, Morando, DW. Anemia screening. StatPearls Publishing. Updated August 4, 2020. Accessed March 19, 2021. http://www.ncbi.nlm.nih.gov/books/NBK499905/

Maakaron JE, Taher AT, Conrad ME. Anemia: Practice essentials, pathophysiology, etiology. Besa EC, ed. Medscape. Updated November 26, 2019. Accessed March 19, 2021. https://emedicine.medscape.com/article/198475-overview

Means Jr. RT, Brodsky, RA. Diagnostic approach to anemia in adults. In: Mentzer WC, ed. UpToDate. Updated February 2021. Accessed March 19, 2021.  https://www.uptodate.com/contents/diagnostic-approach-to-anemia-in-adults

MedlinePlus: National Library of Medicine. Anemia. Updated July 29, 2016. Retrieved March 19, 2021. https://medlineplus.gov/anemia.html

MedlinePlus: National Library of Medicine. Iron deficiency anemia. Updated February 6, 2020. Accessed April 15, 2021. https://medlineplus.gov/ency/article/000584.htm.

National Heart, Lung, and Blood Institute. Anemia. Date unknown. Retrieved March 19, 2021. https://www.nhlbi.nih.gov/health-topics/anemia

National Heart, Lung, and Blood Institute. Your guide to anemia. Published September 2011. Accessed March 19, 2021. https://www.nhlbi.nih.gov/files/docs/public/blood/anemia-yg.pdf

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