What Is Poikilocytosis?

Reviewed by Dan Brennan, MD on April 12, 2021

‌Red blood cells carry oxygen from the lungs to other cells throughout the body and return carbon dioxide to the lungs. Normal red blood cells are in the shape of a disk, thicker on the edge and thinner in the middle (biconcave). 

The term poikilocytosis refers to a condition where 10% or more of the red blood cells are abnormally shaped due to other medical conditions. These cells may have point-like projections or may include shapes that are flat, elongated, teardrop, or in the shape of a sickle or crescent.

Symptoms of Poikilocytosis

‌Symptoms of poikilocytosis depend on the root medical condition. They often include signs that the body’s tissues are not getting enough oxygen delivered by the red blood cells, such as:

  • Chronic fatigue
  • ‌Weakness
  • ‌Pale complexion
  • ‌Difficulty breathing
  • ‌Heart palpitations

‌However, these same symptoms could point to chronic inflammation, so your doctor will need to perform a blood test.

Types of Poikilocytosis

‌Understanding the causes of poikilocytosis and starting treatment early requires knowing about the several types — or cell shapes. The common types are:

  • Sickle cells (Drepanocytes)
  • ‌Cup shaped cells (Spherocytes)
  • ‌Teardrop cells (Dacrocytes)
  • ‌Spur cells (Acanthocytes)
  • ‌Hollow cells (Schistocytes
  • ‌Oval or elongated cells (Elliptocytes)
  • ‌Target cells (Codocytes)
  • ‌Burr cells (Echinocytes)‌‌

Diagnosis for Poikilocytosis

‌Poikilocytosis can be diagnosed using a blood-smear test. A complete blood count ( CBC) test is the most common test for diagnosing a variety of underlying medical conditions including cancer and anemia.

In a CBC, electronic instruments count red blood cells, white blood cells, and platelets. The total cell count is registered as well as estimating the average volume and variation in size. 

‌A blood sample is taken and sent to a lab for analysis. A result is normal when the cells have a normal appearance, and the count is within the normal range. An abnormal result occurs when the shape, color, or size of the red blood cells are not normal. 

‌A four-point scale indicates the percentage of cells affected:

  • 1 = 25%
  • ‌2 = 50%
  • ‌3 = 75%
  • ‌4 = 100%

If the diagnosis is unclear, additional tests may be required. These may include a red blood count enzyme test, taking a bone marrow sample, isoelectric focusing, or a membrane protein test.


The three main types of anemia are iron deficiency anemia (the most common type), thalassemia, and anemia of chronic disease.


As a protein that stores iron, serum ferritin can be measured to determine iron stores, although one downside is that the test is sensitive to the timing of meals. Less than 20 milligrams per liter of serum ferritin is a sign of iron deficiency anemia, whereas the presence of serum ferritin greater than 100 milligrams per liter is consistent with anemia of chronic inflammation.

Iron deficiency also affects many patients with chronic inflammatory bowel disease, heart failure, and chronic kidney disease.

Causes of Poikilocytosis

‌The medical causes of poikilocytosis vary by the type of cell shape. Common causes of abnormal red blood cells include:

  • Drepanocytes (sickle cells): sickle cell disease
  • ‌Spherocytes (cup shaped): autoimmune disorders, transfusion reactions, diseases of newborns, or snakebites
  • ‌Dacrocytes (teardrop cells): leukemia, megaloblastic anemia, or myelofibrosis
  • ‌Acanthocytes (spur cells): liver disease, kidney disease, thalassemia, autoimmune hemolytic anemia, or McLeod syndrome
  • Schistocytes (hollow cells): hemolytic anemias, burns, sepsis, and platelet disorders
  • ‌Elliptocytes (oval or elongated cells): iron deficiency, myelofibrosis, or megaloblastic anemia
  • ‌Codocytes (target cells): liver disease, iron deficiency, hemoglobin C disease, or spleen removal
  • ‌Echinocytes (burr cells): a deficiency of the pyruvate kinase enzyme, kidney disease, or cancer


While poikilocytosis occurs in about 12% of cancer patients, anemia or uremia may or may not be present. Of those cancer patients showing evidence of poikilocytosis, only 50% are typically expected to survive.

Poikilocytosis can also result from the coexistence of acne, functional gallbladder disorder, and mite infection. 

Treatment for Poikilocytosis

‌Managing poikilocytosis requires the diagnosis and treatment of the underlying medical condition. 

As many as 80% of children worldwide develop anemia before the age of eighteen. Therefore, all infants should be screened for anemia. The doctor will look for signs of anemia including pallor, glossitis, changes in the nail beds, and delayed growth.

Usually, anemia in children is caused by iron deficiency in their diet and is treated with an iron supplement. Iron supplements can be given to children before breakfast in the form of ferrous sulfate. The recommended dosage is 3 to 6 megagrams per kilogram of the child’s weight.

‌Children with anemia usually do not show symptoms, but they may display other signs such as fatigue, jaundice, or a pale complexion. 


Treatment can be long-term for poikilocytosis caused by sickle cell disease or thalassemia. It may include blood transfusions or bone marrow transplants.

Other causes such as liver disease may require a liver transplant. Sepsis or serious infections can be treated with antibiotics.

Complications of Poikilocytosis

‌The long-term consequences of untreated iron deficiency are frequently irreversible. These may include poor scores on standardized tests and delayed growth as well as a deficit in dopamine receptors. This can be avoided by making sure children are screened for iron deficiency before reaching their second year.

Complications from poikilocytosis vary and stem for the root disorder causing the abnormal cells. For example, complications arising from sickle cell disease include:

  • ‌Infections (including bone)
  • Stroke
  • ‌Severe chest pain
  • ‌Anemia
WebMD Medical Reference



‌American Family Physician: “Anemia in Children.”

Hematology: “New diagnostic tools for delineating iron status.”

‌Hospital of the Good Samaritan Medical Center and the University of Southern California School of Medicine: “Poikilocytosis in Cancer Patients.”

‌Mayo Clinic Proceedings: “How to Interpret and Pursue an Abnormal Complete Blood Cell Count in Adults.”

‌Mount Sinai: “Blood smear.”

StatPearls: “Poikilocytosis.”

‌Sumy State University: “Poikilocytosis in the Acne Vulgaris Comorbidity with Demodicosis and Functional Gallbladder Disorder.”

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