What Blood Test Shows Anemia?

Anemia Blood Test — Testing for Anemia (Low Red Blood Cell Count)

Anemia is a blood disorder where you suffer from low red blood cell (RBC) count. Blood testing can help confirm its presence. 

That said, many blood tests can detect anemia. A complete blood count (CBC) is just one of them.

Quick Facts on Blood Tests for Anemia

• Anemia is a blood disorder linked to inadequate red blood cell count
• Some symptoms of anemia are tiredness, shortness of breath, pallor, and headaches
• Testing for anemia can help with proper diagnosis and treatment

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Why Take An Anemia Test?

Mild cases of anemia may show few or no symptoms. Diagnostic anemia testing can check if your RBC count is adequate or below normal.

People without symptoms can learn they have anemia after a routine blood test. Complete blood analysis can help doctors narrow down possible conditions causing your anemia.

In severe or chronic blood loss cases, a doctor may also request an anemia test to see how much blood you’ll need for blood transfusions.

What Does An Anemia Test Check For?

An anemia test checks the number and quality of your red blood cells. Anemia usually occurs when you don’t have enough healthy RBCs or when they don’t function properly.

For example, aplastic anemia prevents your bone marrow from making enough blood cells for all cell lines. This means you may have a low red blood cell count.¹

Sickle cell anemia affects the shape and function of RBCs. Their unusual sickle shape cannot carry enough hemoglobin and triggers the spleen to destroy them, leading to a low RBC count.² 

How To Test for Anemia (Low RBC Count)

Anemia tests are done by collecting blood samples. If you have symptoms of anemia, talk to your doctor so they can help you decide which tests you should take:

Anemia Lab Tests

Anemia testing can be done at your doctor’s office, a laboratory, or any medical setting. They will collect a sample of your blood with a needle or from a finger prick.

Routine blood testing can detect if you have anemia. Your doctor may also order tests if you show anemia symptoms or have chronic or severe blood loss.

People undergoing anemia treatments may need follow-up testing. Blood tests can check if your body responds well to medication or iron supplements. 

At-Home Anemia Test

You may also test for anemia at home. There are testing kits that check for blood levels that are important to the diagnosis of anemia, such as:

• Hemoglobin tests — measures if you have a low amount of hemoglobin. They’re the protein in RBCs that carry oxygen throughout the body.
• Ferritin tests — check your body’s capacity to store iron. Ferritin is the protein in your blood linked to your body’s iron level.

At-home blood tests have self-collection tools for your blood sample. If your RBC level is below normal, you should see a doctor to get a proper diagnosis.

What Blood Tests Show Anemia?

A complete blood count (CBC) test is the primary blood test for anemia. But various other tests can diagnose the cause of your anemia:

Complete Blood Count (CBC)

A CBC test is often part of a routine health check-up. It’s essential in diagnosing health problems, including anemia.

The CBC examines the different blood cells, Red Blood Cells (RBCs), White Blood Cells (WBCs), and platelets. It also provides information on a person’s hemoglobin level. Hemoglobin is the protein in the RBC that enables iron molecules to carry oxygen.

Most patients may not need in-depth testing. But additional blood testing can determine the cause and the type of your anemia.

Additional Tests for Abnormal CBC Blood Count

If your blood test shows an abnormal CBC, your doctor may order further testing, such as:

• Blood smear — checks the number, shape, and types of different blood cells
• Differential blood count — measures your total white blood cells (WBCs) and gives a percentage of the different types present in your blood
• Reticulocyte count — measures the body’s capacity to make new red blood cells in your blood³

Tests for Red Blood Cell Destruction

Some anemia types occur when your body destroys the RBCs before producing new ones. These tests can see if there’s a premature breakdown of red blood cells:

• Hemoglobinopathy evaluation — evaluates the form and structure of your hemoglobin molecule. It also looks for abnormal hemoglobin.
• Haptoglobin test — measures the protein in the blood cells that indicate how fast your body destroys the RBCs. This is done if hemolytic anemia is suspected.⁴
• Lactate dehydrogenase (LD) test — measures the enzyme that indicates tissue or cell damage as a by-product of RBC destruction
• Osmotic fragility test — evaluates the resistance of your RBCs to breakdown
• G6PD levels— measures the level of the enzyme glucose-6-phosphate dehydrogenase. It helps your RBCs to work correctly.
• Direct antiglobulin test — detects circulating antibodies that may attack your RBCs

Tests for Blood Coagulation

Anemia can result from excessive bleeding. These tests look for signs of abnormal blood clotting and related bleeding disorders.⁵

• Partial thromboplastin time — measures the proteins involved in blood cot formation. A prolonged value causes excessive bleeding.
• Thrombin time (TT) — looks at how long it takes for your blood to clot. It can help detect if you have bleeding problems.
• Prothrombin time and international normalized ratio (PT/INR) — measure how long your blood takes to form a clot.

Tests for Iron Deficiency Anemia

Iron deficiency is the world’s leading cause of low RBC count. Iron is an essential element in the production of red blood cells. An inadequate iron level leads to small and pale RBCs.⁶ 

Your doctor can assess if you have iron deficiency anemia with these tests:

• Serum iron — tests how much iron is in your blood.
• Ferritin Blood — measures the amount of blood protein that attaches to iron.
• Transferrin and total iron-binding capacity (TIBC) — measure the blood’s ability to bind and transport iron.
• Soluble transferrin receptor (sTfR) —  measures the protein that increases when low on iron.

Tests for Nutrient Deficiencies

Your body needs specific vitamins to produce healthy red blood cells. Your doctor may test you for nutritional deficiency if they think it’s causing your anemia.⁷  

• Vitamin B12 and folic acid testing — measures the amount of vitamin B12 and folate in your body. These nutrients are essential in producing healthy RBCs
• Methylmalonic acid (MMA) — tests the acid in your blood that drops when your body's vitamin B12 decreases   
• Homocysteine — measures if the acids in your blood linked to a vitamin deficiency are elevated. The elevation of homocysteine levels is associated with lowering vitamin B12 in the body.
• Intrinsic factor antibody — measures the protein released by your stomach lining. Intrinsic factor helps your body absorb vitamin B12 from the foods you eat.
• Parietal cell antibody — looks for antibodies that attack the parietal cells. Parietal cells produce substances that help the body absorb vitamin B12.  

Tests for Other Health Problems Linked to Anemia

Some underlying health conditions can set off anemia. Your doctor may order these tests to identify problems related to your low RBC count:

• Comprehensive metabolic panel (CMP) — a blood test that measures 14 different substances in your blood. They are linked to your kidney and liver function.⁸
• Liver panel — checks the overall health of your liver. It measures the enzymes, proteins, and other substances your liver produces.⁹
• Kidney (renal) panel — checks how well your kidney functions. It measures the compounds related to your kidney’s health, such as electrolytes, minerals, and proteins.
• C-Reactive protein (CRP) — measures the protein in your blood that increases when there's inflammation in the body¹⁰
• Heavy metal testing — checks the level of potentially toxic metals that may affect your bone marrow. It includes heavy metals such as lead, arsenic, and mercury.

Tests for Infections That Cause Low RBCs

Some infections can affect your body's ability to maintain a healthy RBC count:

• HIV — looks for antibodies or antigens linked to an HIV infection. HIV can increase the risk of anemia by destroying RBC or lowering RBC production.    
• Epstein-Barr Virus (EBV) — looks for EBV antibodies. EBV causes mono, which may affect the production of RBC.
• Cytomegalovirus (CMV) — looks for CMV antibodies. CMV infection causes many health problems, including anemia¹¹ 

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