Poikilocytosis is a term that refers to the presence of abnormally shaped red blood cells (RBCs), which are known as poikilocytes. As poikilocytosis is usually a symptom of another medical condition, the treatment options will differ depending on the underlying cause.

RBCs, which are also called erythrocytes, are one of the four main components of blood. RBCs carry oxygen from the lungs to cells in other parts of the body and then return carbon dioxide to the lungs for exhalation. The normal shape of RBCs allows them to carry out this function optimally. Typically, these cells are disk-shaped and biconcave, which means that they are thinner in the middle than around the outer edge.

Poikilocytosis describes an increase in the number of abnormally shaped RBCs, whereby they make up 10% or more of the total count. Poikilocytes have abnormal features, which may include being flatter or elongated, having pointy projections, or forming unusual shapes, such as teardrop, crescent, or sickle shapes.

In this article, we look at the causes, symptoms, types, and treatment of poikilocytosis.

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Poikilocytosis occurs when an underlying medical condition affects the appearance of RBCs. In some cases, a person may inherit a genetic mutation that gives them a condition that results in poikilocytosis. However, some acquired conditions that people develop later in life can also lead to poikilocytosis.

Inherited causes of poikilocytosis can include:

Acquired cases of poikilocytosis may be due to:

The symptoms of poikilocytosis depend on the underlying condition that is causing abnormally shaped RBCs. However, the symptoms often result from the body’s tissues not receiving enough oxygen through the RBCs. As a result, they may include:

  • chronic fatigue
  • pale complexion, which may be more apparent in people with light skin tones
  • weakness
  • difficulty breathing or shortness of breath
  • heart palpitations

There are many different types of poikilocytosis, and the diagnosis depends on the shape of the RBCs. The most common types are sickle cells, target cells, spherocytes, elliptocytes, echinocytes, and acanthocytes. Other types include dacrocytes, schistocytes, and stomatocytes.

Sickle cells

Sickle cells, also called drepanocytes, are crescent-shaped and longer than normal RBCs. This type of poikilocytosis is a common symptom of sickle cell diseases, such as sickle cell anemia and hemoglobin S-thalassemia.

Target cells

Target cells, also called codocytes, have a shape that resembles a bullseye. These cells are typically the result of the following:

Spherocytes

Spherocytes are small, dense cells that do not have the lighter colored center that is present on a normal RBC. Spherocytes are usually the result of the following conditions:

Elliptocytes

Elliptocytes, often called ovalocytes, have an oval shape with blunt ends. Elliptocytes are a common feature of the following conditions:

  • iron deficiency anemia
  • thalassemia
  • megaloblastic anemia
  • myelofibrosis

Echinocytes

Echinocytes, sometimes called burr cells, have thorny projections called spicules that outline the cell membrane. Echinocytes are present in several conditions, including:

  • pyruvate kinase deficiency
  • kidney disease
  • cancer

Acanthocytes

Acanthocytes, often called spur cells, look similar to echinocytes because both cell types have spicules on the edge of the cell membrane. However, acanthocytes tend to have fewer spicules than echinocytes, and these projections are typically less evenly spaced. Acanthocytes commonly have an association with:

  • liver disease
  • thalassemia
  • abetalipoproteinemia
  • splenectomy
  • autoimmune hemolytic anemia
  • kidney disease
  • McLeod syndrome

Dacrocytes

Dacrocytes, also called teardrop cells, have both a round end and a pointy end. They are present in conditions such as:

  • megaloblastic anemia
  • leukemia
  • hemolytic anemia
  • beta-thalassemia
  • myelofibrosis

Doctors usually diagnose poikilocytosis using a blood smear test. During a blood smear test, a medical technologist spreads a thin layer of blood on a slide and uses a microscope to look closely at the shapes of RBCs.

Individuals with poikilocytosis will have some normally shaped RBCs, and they may even have multiple types of poikilocytosis. The doctor will determine which type is the most prevalent so that they can make an accurate diagnosis.

After diagnosing poikilocytosis, the doctor will try to determine the underlying cause. To do this, they may ask about the person’s medical and family history, as well as carrying out other diagnostic tests.

Individuals with this condition will likely require information about the cause of their poikilocytosis and the different treatment options available.

The treatment of poikilocytosis will involve addressing the underlying condition that is causing the abnormal RBCs and preventing any potential complications. For example, conditions that result from a nutrient deficiency, such as anemia, are treatable with diet and supplements. Genetically acquired forms of anemia, such as sickle cell anemia, are typically manageable, but a person may require lifelong treatment to reduce symptoms and complications.

Poikilocytosis refers to abnormally shaped red blood cells. Poikilocytes typically develop due to an underlying medical condition that alters their shape. Examples include certain types of anemia, liver disease, kidney disease, and cancer.

Poikilocytosis itself is not a fatal condition, but it indicates an underlying medical condition. Its presence can result in doctors diagnosing some underlying conditions before complications occur. A doctor will be able to recommend the most suitable treatment options.