Different blood tests, including a complete blood count (CBC), iron test, or B12 test, can help diagnose anemia, which can have different causes.
Anemia occurs when there are not enough healthy red blood cells or hemoglobin in the blood to transport oxygen to cells.
A CBC can reveal if a person has enough red blood cells, but further tests can confirm the cause of the anemia. Often, the cause is an iron deficiency, but it could be another nutrient deficiency or health condition.
Read on to learn more about anemia blood tests, what they measure, what the results mean, and whether it is possible to test at home.
A note about sex and gender
Sex and gender exist on spectrums. This article will use the terms “male,” “female,” or both to refer to sex assigned at birth. Click here to learn more.
Doctors can diagnose anemia by testing a person’s red blood cell count. To measure this, they perform a CBC.
According to the
- red blood cells
- white blood cells
- platelets
To find the cause of anemia, the doctor may also order other blood tests.
The section below breaks down the different tests a doctor may use to diagnose anemia and what each one measures.
CBC
A CBC measures the
- Red blood cells: If these are higher or lower than the typical range, it could signify anemia.
- Hemoglobin: High or low levels of hemoglobin may indicate anemia. Hemoglobin is an iron-rich protein within red blood cells that transports oxygen.
- Hematocrit: Hematocrit is the volume of red blood cells in the blood. If these levels are too low, it may be a sign of anemia.
- Mean corpuscular volume (MCV): MCV refers to the average size of red blood cells. If this is higher or lower than the typical range, it may indicate anemia.
Other blood tests a doctor may perform include:
- a reticulocyte count, which measures the number of immature red blood cells that the bone marrow is producing
- a blood smear test, which allows doctors to describe the appearance and number of blood cells
Iron test
A test for iron deficiency anemia may test:
- serum iron, which is the total amount of iron in the blood.
- transferrin, which is a protein that moves iron throughout the body.
- total iron-binding capacity, which measures how well iron attaches to transferrin and other proteins in the blood
- ferritin, which is a protein that stores iron
Other tests
Other tests a doctor may order to find or confirm the cause of anemia
- folate test
- vitamin B12 test
- thyroid function tests
There is no single set of results that indicates all types of anemia. Different forms of anemia can produce different results, which is why doctors interpret these tests.
However, the most common cause is iron deficiency anemia, which typically causes:
- low hemoglobin and hematocrit
- low mean cellular volume
- low ferritin
- low serum iron
- high transferrin or total iron-binding capacity
- low iron saturation
The table below demonstrates the expected ranges for a CBC in adult males and females:
| Test levels | Healthy range for males | Healthy range for females |
|---|---|---|
| Red blood cells | 4 to 5 million cells/mcL | |
| Hemoglobin | 14 to 17 grams per deciliter (gm/dL) | 12 to 15 gm/dL |
| Hematocrit | 41% to 50% | 36% to 44% |
| MCV | 80 to 95 femtoliters | 80 to 95 femtoliters |
This table shows the expected range of iron and ferritin in the blood for adults:
| Levels | Typical | Iron deficiency anemia |
|---|---|---|
| Iron micromoles per liter (mcmol/L) | Less than 10 | |
| Ferritin mcmol/L | 40 to 300 for males 20 to 200 for females | Less than 10 |
Levels that fall outside the expected range could indicate anemia, but other factors may influence these tests, such as:
- pregnancy
- high altitude
- certain medications
- other medical conditions
- what a person has eaten that day
When a person has anemia but the cause is unclear from initial blood tests, doctors may refer them to a hematologist, or blood disorder specialist.
A person may require further tests to find the root cause, which may
- Urine tests: These tests check whether the kidneys are working correctly and if there is any bleeding in the urinary tract.
- A colonoscopy: This test assesses a person’s colon for bleeding or other problems such as tumors. Doctors may also check for blood in stool.
- An endoscopy: This looks for bleeding in the esophagus (food pipe), stomach, and the first part of the small intestine.
- A bone marrow test: These tests can show whether bone marrow is making enough blood cells. Doctors
often perform two bone marrow tests at the same time: an aspiration and a biopsy. Aspiration involves taking a small amount of bone marrow fluid, while a biopsy involves collecting a small sample. - Infection tests:
Sometimes , infections such as viral hepatitis, Epstein-Barr virus, and HIV can cause aplastic anemia, which is when stem cells in bone marrow become damaged. - Genetic tests: These look for changes in the genes that control how the body makes red blood cells.
Yes, in some cases, this may be possible.
At-home iron tests are available for people to test for iron deficiencies at home. This may only require a few drops of blood to perform, meaning individuals can carry out the test with a finger prick instead of going to a doctor’s office.
People receive these kits by mail and then send them to a laboratory. They may get the results online, in an app, or via letter, which they can share with their doctor.
However, it is important to note that iron deficiency anemia is not the only type of anemia. For a full CBC and other tests, people may need to contact a doctor.
Mild or moderate iron-deficiency anemia
- tiredness
- shortness of breath
- chest pain
- fatigue
- dizziness or lightheadedness
- cold hands and feet
- pale skin
Other symptoms of iron-deficiency anemia may also include:
- pale or yellowed skin
- lack of energy
- unexplained generalized weakness
- rapid heartbeat
- pounding or “whooshing” in the ears
- headache
- craving for ice or clay, which is known as picophagia
- sore or smooth tongue
- brittle nails
- hair loss
People need to speak with a doctor if they have these symptoms.
A complete blood count (CBC) can help diagnose anemia. This includes tests for red blood cell count, hemoglobin, and hematocrit levels. If these levels are irregular, it can indicate anemia.
Doctors may confirm the cause of anemia with other tests, such as an iron test, B12 test, folate test, or blood smear.
It is possible to test iron levels at home with an at-home testing pack, but these may not cover all of the tests a doctor would perform and may miss things.
If a person suspects they have anemia or has any unexplained symptoms, they can consult a doctor.