What Is Poikilocytosis?

Introduction

The word ‘poikilocytosis’ refers to the presence of irregularly shaped red blood cells (RBCs) in the blood, called poikilocytes. Red blood cells (also known as erythrocytes) are disc-shaped cells with the middle of the cell being thinner than the edges. The shape of poikilocytes can be elongated, teardrop-shaped, flat, or even crescent-shaped. They could also appear to have point-like projections. The presence of these abnormally shaped cells may provide insight into identifying the underlying pathophysiology.¹

Causes of poikilocytosis

Poikilocytosis is most commonly caused by conditions such as iron deficiency anaemia, megaloblastic anaemia, thalassemia, sickle cell disease, and liver disease. The most common types of poikilocytosis include sickle cells, target cells, echinocytes, ovalocytes, elliptocytes, spherocytes, and acanthocytes.¹

Trauma from the environment or internal injury can lead to poikilocytosis. In general, poikilocytosis causes can be either inherited or acquired. Genetic mutations or anomalies can cause inherited conditions which are present from birth, whereas the majority of acquired illnesses manifest later in life.¹

Inherited causes include:¹

• Sickle cell anaemia, which is characterised by the presence of RBCs with an irregular crescent shape and elongated spicules, is known as sickle cells or drepanocytes
• Thalassaemia, is another hereditary disease where target cells, also known as codocytes, are involved in the production of abnormal haemoglobin
• Hereditary spherocytosis, where spherocytes are present
• Pyruvate kinase deficiency, burr cells or echinocytes are present
• Hereditary elliptocytosis, where epistocytes are present
• MacLeod syndrome, a rare genetic condition where acanthocytes are present

Acquired causes include:¹

• Elliptocytes (ovalocytes) are seen in iron deficiency anaemia, a common form of anaemia caused by inadequate iron levels in the body
• Elliptocytes and dacrocytes, or teardrop cells, are found in megaloblastic anaemia brought on by folate or vitamin B-12 deficiency
• Usually schistocytes and spherocytes are present in autoimmune haemolytic anaemia.
• Burr cells, or echinocytes, are found in liver and renal disorders
• There are acanthocytes present in liver disease associated with alcohol
• There are teardrop cells in myelofibrosis
• Heavy metal-related lead poisoning
• Infections such as Babesia and Plasmodium

Types of poikilocytes

There are many types of poikilocytes, many of which are included in the table below:

Diagnostic methods

• Blood smear examination – this is carried out to identify abnormal RBC shapes under the microscope. Patients with poikilocytosis will have some normal RBCs mixed with the abnormally shaped RBCs. Different types of poikilocytes will be present depending on the condition of the patient¹
• Peripheral blood morphology – analysing the shape of the RBCs using grading systems provides insight into the patient’s health, as well as being able to detect different poikilocytes and aid in diagnosing disorders⁴
• Laboratory tests – carrying out different laboratory tests aid in the confirmation of the diagnosis and identify any underlying causes. There are many different types of laboratory tests carried out such as serum iron levels, vitamin B₁₂, folate, complete blood count, and liver function tests¹

Clinical significance of poikilocytosis

Clinical significance

Poikilocytosis can be used as an indicator for a variety of disorders, allowing for targeted research. Due to the irregularly shaped RBCs, oxygen is not able to be carried as efficiently by the cells. Subsequently, the patient may present with palpitations, fatigue, shortness of breath, and weakness, and may appear pale-skinned (although this may look different on people with different skin tones). Analysing symptoms and results from blood tests and a blood smear can help in narrowing down the disorder. For instance, the presence of target cells may suggest the need for further tests to evaluate for sickle cell disease.¹

Treatment and management of poikilocytosis

Addressing underlying causes

Treating the underlying cause is important in managing the irregular morphology of the RBCs. There are different treatment options available depending on the condition. For example, acquired conditions such as megaloblastic anaemia, iron deficiency anaemia, or vitamin B­₁₂ are usually treated by patients increasing their iron or vitamin levels by adjusting their diet and/or by taking supplements. Underlying diseases such as coeliac disease may have caused the deficiency and are treated accordingly.¹

Symptomatic treatment

For inherited conditions such as sickle cell anaemia or thalassaemia, prolonged treatment is required, such as the use of hydroxyurea or regular blood transfusions.⁵ Lifelong monitoring and treatment are usually required for genetic conditions. For these conditions, blood transfusions or a bone marrow transfer may be required. In cases of liver disease, a liver transplant may be required depending on the severity of the disease. Antibiotics may be used when a patient is septic or has a serious infection.¹

Health outcomes

Impact on health outcomes

The underlying cause of poikilocytosis and the time of intervention determines the prognosis. Early detection and early management can significantly improve the outcome for the patient. Iron deficient disorders such as megaloblastic anaemia, iron deficiency, and low vitamin B₁₂ have good predicted health outcomes as the underlying nutritional deficiency can be corrected.¹

Long term considerations

Monitoring for potential problems and modifying treatment methods are necessary as long-term considerations. Comprehensive care and frequent check-ups are important for maintaining long-term well-being. Conditions such as sickle cell disease and thalassaemia may have poorer prognoses depending on the presentation of the condition and whether complications arise. Complications such as vaso-occlusive crises (blockage of blood flow to tissues by sickle cells)⁶ and infections will require lifelong treatment.¹

Complications with poikilocytosis

The poikilocytosis' underlying aetiology (biological cause) affects complications as well. Occasionally, the underlying dyserythropoietic (impaired RBC development)⁷ may be overshadowed or obscured by the severity of the condition. Poikilocytosis can be used as a diagnostic aid when combined with careful observation and clinical acumen.¹

Complications of sickle cell disease include infections, acute chest syndrome, and haemolytic crisis. Complications of anaemia include delayed growth in children, heart failure, and palpitations.¹

Summary

Poikilocytosis is a significant indicator of underlying health conditions. The irregular shape of the RBCs provides insight into the pathophysiology of a number of diseases. Poikilocytosis has a wide and complex aetiology since it can result from both acquired and inherited factors. While acquired conditions like iron deficiency anaemia emphasise the impact of environmental variables and internal damage, inherited causes like sickle cell anaemia highlight the importance of genetic abnormalities. Laboratory tests, blood smears, and peripheral blood morphology are ways for clinicians to form a diagnosis and then decide on effective treatment and management. Tailored approaches are used in treating and managing either acquired or inherited conditions. Prognosis relies on early detection of the condition and early intervention, especially for conditions linked to nutritional deficiencies as they exhibit positive prognoses. This highlights the importance of vigilant monitoring and interventions to guide us towards optimal health for patients.