Introduction

Poikilocytosis refers to abnormally shaped red blood cells (RBCs) in the bloodstream. Normal RBCs (erythrocytes) are disk-shaped, thinner at the margins, and have a diameter of 6.2 to 8.2 micrometres. Poikilocytosis is defined as an increase of abnormally shaped red blood cells which account for 10% or more of all red blood cells. Abnormally shaped RBCs (poikilocytes) may have a number of different abnormalities. They can be

• Flat, 
• Elongated 
• Teardrop-shaped
• Crescent-shaped 

Poikilocytes can also have point-like or thorn-like projections or have other abnormal characteristics.¹

It is important to understand the importance of diagnosis and treatment. Receiving a correct diagnosis is a vital aspect of healthcare. It explains a patient's health condition and guides subsequent medical treatment decisions. A mistake in diagnosis may result in adverse consequences to your health, mental anguish, and financial losses. If an error in diagnosis occurs, a patient may get incorrect medical treatment, while appropriate or possibly life-saving treatment may be withheld or delayed.²

The diagnosis of poikilocytosis involves an evaluation of the patient’s medical history, physical examination, and laboratory tests. Once the patient has been diagnosed with poikilocytosis, various treatment strategies can be initiated to address the underlying cause of this condition and to reduce the symptoms. 

Causes of poikilocytosis

Inherited conditions

Many hereditary diseases that cause poikilocytosis affect the genetic code (DNA) required for the red blood cells to grow, function, and survive. The red blood cells with faulty DNA often break down prematurely, before your body can replace them with new ones. This is known as hemolytic anaemia. 

The various inherited conditions that could result in poikilocytosis include:

• Hereditary elliptocytosis: A hereditary heterogenous red blood cell (RBC) condition characterised by elongated, oval, or elliptical-shaped red blood cells on a peripheral blood smear 
• Hereditary spherocytosis: A hereditary blood condition that generally results in hemolytic anaemia. This anaemia happens because your red blood cells break down quicker than usual. Hereditary spherocytosis causes your red blood cells to lose their disc-like shape and become round or spherical cells (spherocytes). Unfortunately, these spherocytes cannot function like normal red blood cells 
• McLeod syndrome: This is a genetic disorder mainly seen in people assigned male at birth and affects the blood, brain, peripheral nerves, muscles, and heart 
• Pyruvate kinase deficiency: A rare genetic condition that causes red blood cells to break down faster than usual 
• Sickle cell disease: This condition affects the haemoglobin found in red blood cells. This genetic defect causes abnormal haemoglobin to clump together, leading to sickle-shaped red blood cells
• Thalassemia: This is a hereditary condition that impairs the body’s capacity to produce haemoglobin and healthy red blood cells 

Acquired conditions

Several conditions that develop over time might result in abnormally shaped red blood cells. 

Acquired conditions that might result in poikilocytosis include: 

• Autoimmune hemolytic anaemia: This is a rare immune disease. This condition usually occurs when your body mistakes red blood cells for a foreign substance and attacks them
• Iron deficiency anaemia: This condition occurs when your body does not produce enough red blood cells due to low concentrations of iron in your blood 
• Kidney diseases: In this condition, your kidneys lose function, resulting in poikilocytosis
• Leukaemia: This condition occurs when the DNA of a single bone marrow cell changes. This will prevent RBCs from developing and functioning properly³

Types of poikilocytes

1. Sickle cells: Your red blood cells become crescent- or “sickle”-shaped due to a genetic condition 
2. Spherocytes: The red blood cells are shaped like a sphere rather than a disc. When compared to disc-shaped red blood cells, these sphere-shaped red blood cells are more fragile 
3. Elliptocytes: This is a genetic disorder in which the red blood cells are elliptical rather than having a typical round shape 
4. Ovalocytes: In this condition, red blood cells will be oval rather than round 
5. Echinocytes: In this condition, red blood cells will have an abnormal cell membrane that is characterised by small, evenly spread thorny projections¹ 

Diagnosis of poikilocytosis

The diagnosis of Poikilocytosis is done by blood smear examination. This test may be performed as a part of a standard physical examination or if the patient is suffering from anaemia or other unexplained symptoms. Not all RBCs will have an abnormal shape. 

Patients with poikilocytosis have some normal-shaped RBCs mixed with abnormally-shaped poikilocytes. In conditions such as iron deficiency anaemia and megaloblastic anaemia, a single patient’s blood smear may include different types of poikilocytes.¹ During a blood smear test, a lab technician examines a blood sample under a microscope.

A peripheral blood smear test is usually ordered with a complete blood count (CBS) by the physician. A complete blood count is a test that collects information about your blood cells, including their levels and size. Certain values on the complete blood count may offer additional information about your red blood cells that help your physician to determine the cause of poikilocytosis, including:

• Mean corpuscular volume (MCV): The average size of your red blood cells
• Mean corpuscular haemoglobin (MCH): The average quantity of haemoglobin in red blood cells
• Mean corpuscular haemoglobin concentration (MCHC): The average haemoglobin concentration in your red blood cells
• Red cell distribution width (RDW): Refers to the size variations of your red blood cells³ 

Treatment options for poikilocytosis

Poikilocytosis is treated based on the underlying causes. If poikilocytosis is caused by low levels of iron, vitamin B12, or folate, it is usually treated by taking supplements and increasing the levels of iron or these vitamins in the diet. Additionally, any underlying diseases that have caused the deficiency will be treated as well.

Poikilocytosis caused by genetic conditions such as thalassemia or sickle cell anaemia may need long-term therapy. Genetic conditions, in general, require lifelong monitoring and treatment when the disease periodically gets worse. These patients may need blood transfusions or a bone marrow transplant. In individuals who are having additional manifestations of poikilocytosis, such as liver disease, this should be treated appropriately as well. Some individuals may need a liver transplant, while those with sepsis or serious infections may need antibiotics.¹ 

Complications of poikilocytosis

The majority of cases of poikilocytosis are treatable, if not reversible. Without treatment, some cases may be fatal. For example, if you have anaemia, you may feel exhausted and unable to carry out your everyday activities. Over time, a shortage of healthy red blood cells may lead to organ failure.

Untreated anaemia in children can slow their growth and development.

Once your healthcare provider has determined what is causing poikilocytosis, they may recommend treatments to avoid possible long-term consequences.³

FAQ’s

What are the treatments for poikilocytosis?

Poikilocytosis is treated based on the underlying causes. If poikilocytosis is caused by low levels of iron, vitamin B12, or folate, it is usually treated by taking supplements and increasing the levels of iron or these vitamins in the diet. Additionally, any underlying diseases that have caused the deficiency will be treated as well.

What is the clinical significance of poikilocytosis?

Poikilocytosis is defined as abnormally formed red blood cells (RBCs). Poikilocytosis often arises as a result of an underlying medical condition that alters the form of the RBCs. Examples of such conditions include anaemia, liver disease, kidney disease, and cancer.

When should you go to the hospital for iron deficiency anaemia?

Get immediate medical attention if you have difficulty breathing or your heartbeat is irregular.

Summary

Poikilocytosis refers to abnormally shaped red blood cells (RBCs) in the bloodstream. Normal RBCs (erythrocytes) are disk-shaped, thinner at the margins, and have a diameter of 6.2 to 8.2 micrometres. Poikilocytosis is defined as an increase of abnormally shaped red blood cells, which account for 10% or more of all red blood cells. Abnormal RBCs (poikilocytes) may be flat, elongated, teardrop- or crescent-shaped. Poikilocytes can also have point-like or thorn-like projections or other abnormal characteristics. Poikilocytosis may be caused by inherited or acquired conditions.

The diagnosis of poikilocytosis is done by performing a blood smear test. A peripheral blood smear test is usually ordered with a complete blood count by the physician. Poikilocytosis is treated based on the underlying causes. If poikilocytosis is caused by low levels of iron, vitamin B12, or folate, it is usually treated by taking supplements and increasing the levels of iron or these vitamins in the diet. Additionally, any underlying diseases that have caused the deficiency will be treated as well.