Aplastic Anemia: Diagnosis & Subtypes

How is aplastic anemia diagnosed?

Patients with aplastic anemia typically have low blood cell counts in all three blood types - red blood cells, white blood cells, and platelets. Upon examination, the bone marrow is found to be hypoplastic or aplastic, meaning it has low growth or no growth of blood-forming stem cells. Chromosomal abnormalities are not typically found in people with aplastic anemia.

Diagnosing aplastic anemia can be a complex process. Doctors use three main tools to help them diagnose and understand each case of aplastic anemia. These include blood tests, medical history, and bone marrow examination.

Diagnostic Tests

Many tests are used to diagnose aplastic anemia. These tests help:

  • Confirm a diagnosis of aplastic anemia, look for its cause, and find out how severe it is
  • Rule out other conditions that may cause similar symptoms
  • Check for paroxysmal nocturnal hemoglobinuria (PNH)

Blood tests

When trying to figure out the cause of your symptoms, your doctor will ask for blood samples. These samples will be used in a number of tests.

Complete Blood Count (CBC)

One important test is a complete blood count, or CBC for short. The CBC measures the number of each blood cell type in your blood sample. If the CBC shows a low number of red blood cells, white blood cells, or platelets, your doctor may look at the cells under a microscope. This is called a blood smear, and it can show if any blood cells are abnormal.  The CBC also looks at mean corpuscular volume (MCV). MCV is a measure of the average size of your red blood cells. The results may be a clue as to the cause of your anemia.

Learn more about the CBC.

Reticulocyte Count

A reticulocyte count measures the number of young red blood cells in your blood. The test shows whether your bone marrow is making red blood cells at the correct rate. People who have aplastic anemia have low reticulocyte levels.

Other blood tests your doctor may order include:

  • EPO Level. EPO, or erythropoietin, is a protein made in your kidneys. EPO causes your bone marrow to make more red blood cells. A shortage of EPO can cause anemia.
  • Iron Level. A shortage of iron can cause anemia.
  • Vitamin B-12 and Folate Levels. A shortage of these vitamins reduces blood cell production in the bone marrow and causes a drop in the number of white blood cells, red blood cells, and platelets in the blood.

Medical history

To understand what is causing your symptoms and low blood counts, your doctor will take a detailed medical history. He or she may ask you questions like the following:

  • What are your symptoms?
  • What medications or herbal supplements have you been taking?
  • Have you been exposed to harmful chemicals?
  • Did you have chemotherapy or radiation treatments in the past?
  • Is your urine dark or tea-colored in the morning?
  • Has your liver been inflamed recently?

Bone marrow examination

Your doctor or another doctor called a pathologist will take a bone marrow sample from your hip bone to examine. The doctor will look at your liquid bone marrow under a microscope and send a sample of your bone marrow to a lab. The bone marrow test shows:

  • The quantity (cellularity) of your bone marrow occupied by different cells
  • Exactly what types and amounts of cells your bone marrow is making
  • Increased, decreased, or normal levels of iron in your bone marrow
  • Chromosomal (DNA) abnormalities

Learn more about how a bone marrow sample is taken.

What are the subtypes of aplastic anemia?

Doctors classify aplastic anemia into three groups, based largely on the patient's neutrophil count. Neutrophils are a type of white blood cell that fight bacterial infections. These types include:

  • Moderate aplastic anemia (MAA) – Your blood counts are low, but not as low as with severe aplastic anemia. You may have few or no symptoms.
  • Severe aplastic anemia (SAA) – Your neutrophil count is less than 500 cells per microliter.
  • Very severe aplastic anemia (VSAA) - Your neutrophil count is less than 200 cells per microliter.

How common is aplastic anemia?

Aplastic anemia is very rare. Doctors estimate that there are about 900 new cases of aplastic anemia diagnosed in the United States each year.