Erythrocytosis: Definition, Causes & Symptoms

Erythrocytosis is characterized by an unusually high number of red blood cells (RBCs) or erythrocytes in the bloodstream, increasing blood viscosity. This elevated cell count can slow blood flow and lead to various health complications.

If left unmanaged, erythrocytosis can progress to life-threatening problems. Recognizing the symptoms, understanding the causes, and knowing the available treatments are crucial for promptly addressing potential health risks associated with erythrocytosis.

Understanding Erythrocytosis

Blood consists of solid components- red and white blood cells, platelets, and liquid plasma. Erythrocytosis involves excessive RBCs relative to plasma, resulting in increased hematocrit levels that indicate a higher proportion of blood volume occupied by RBCs.

RBCs transport oxygen and remove carbon dioxide, which is essential for maintaining tissue health. However, an excessive number of RBCs can thicken the blood, thereby escalating the risk of blood clots, heart attacks, and strokes due to a reduction in blood flow.

Types of Erythrocytosis

Erythrocytosis is classified into two primary types. Each type arises from different causes and carries distinct health implications, making it essential to understand their differences to ensure appropriate management of this condition.

Primary Erythrocytosis

Primary erythrocytosis is a rare condition characterized by the bone marrow’s overproduction of RBCs. It is classified as a myeloproliferative disorder and is not triggered by external factors.

The excessive production of RBCs in primary erythrocytosis results from a genetic mutation in bone marrow stem cells. This mutation changes the cellular instructions, causing these cells to reproduce uncontrollably and resulting in an abnormally high ratio of RBCs.

Secondary Erythrocytosis

Secondary erythrocytosis occurs when an external factor, such as chronic low oxygen levels, prompts the body to increase RBC production. This condition is a physiological response to ensure adequate oxygen transport throughout the body.

Unlike primary erythrocytosis, which results from a mutation in bone marrow cells, secondary erythrocytosis arises from conditions that reduce oxygen availability. These conditions prompt the body to increase RBC production to enhance oxygen delivery to tissues but in turn disrupt the balance of blood components.

Causes and Risk Factors of Erythrocytosis

Various risk factors can trigger erythrocytosis. Each leads to the overproduction of RBCs, and understanding these factors is crucial for effectively managing and treating the condition.

Genetic Mutations

Genetic mutations play a crucial role in erythrocytosis by altering the regulatory pathways that control RBC production. These mutations can lead to unchecked overproduction of RBCs, contributing to the imbalance of blood components.

Mutations in the JAK2 gene are commonly found in primary erythrocytosis, often referred to as polycythemia vera. This specific genetic alteration impacts the signaling pathways within bone marrow cells, causing them to produce excessive RBCs.

Smoking

Smoking is a notable lifestyle factor that contributes to secondary erythrocytosis. The carbon monoxide in cigarette smoke binds with hemoglobin more effectively than oxygen, reducing the amount of oxygen available to body tissues.

This reduction in oxygen levels causes the body to perceive an oxygen deficit, prompting a compensatory increase in RBC production. This physiological response enhances the blood’s oxygen-carrying capacity, thereby counteracting the effects of oxygen deprivation caused by smoking.

Low Oxygen Environments

Living at high altitudes or having a medical condition that limits oxygen uptake can lead to erythrocytosis. In high-altitude environments, the reduced partial pressure of oxygen results in lower oxygen availability, which leads to tissue hypoxia (low tissue oxygen levels).

In response to reduced oxygen levels, the body increases the production of erythropoietin (EPO), a hormone that stimulates the production of RBCs. This natural adaptation enhances the blood’s capacity to carry oxygen, meeting the body’s increased demands under hypoxic conditions.

Tumors

Certain tumors, particularly those in the kidney, liver, or brain, can influence high levels of EPO, leading to erythrocytosis. Notable cancerous tumors such as renal cell carcinoma, hemangioblastoma, hepatocellular carcinoma, and parathyroid carcinoma are known to produce excessive EPO.

This overproduction of EPO can significantly stimulate the bone marrow to increase RBC production. Benign tumors, like uterine fibroids, pheochromocytoma, and meningioma, can also contribute to erythrocytosis by influencing excess EPO secretion, further complicating the body’s normal regulatory mechanisms.

Medication Use

Certain medications can indirectly cause erythrocytosis by influencing red blood cell production or altering the body’s hydration levels. Androgens and erythropoiesis-stimulating agents are known to increase RBC production, which can subsequently lead to higher hematocrit levels.

Diuretics, commonly prescribed for various medical conditions, can result in dehydration and effectively concentrate the RBCs in the bloodstream. Additionally, the use of anabolic steroids and testosterone, particularly in athletic or bodybuilding contexts, can induce secondary erythrocytosis, further increasing RBC counts.

Health Conditions

Chronic low oxygen levels in the blood are caused by heart issues like congenital heart disease or heart failure. These health conditions impair the heart’s ability to pump oxygen-rich blood, prompting the body to increase RBC production to compensate for the oxygen shortfall.

Chronic lung diseases can decrease lung capacity or disrupt normal breathing. Conditions like sleep apnea, hypoventilation, and obesity can also lower blood oxygen levels. In response, the body increases RBC production to enhance oxygen transport and compensate for the reduced availability of oxygen.

Intense Athletic Activity

Intense physical and endurance training increases the body’s oxygen demand, stimulating EPO production, boosting RBC production in the bone marrow. More RBCs enhance the blood’s oxygen-carrying capacity, improving oxygen delivery to muscles and tissues to meet the heightened demand and thereby benefiting athletic performance.

In addition to the increased demand, some athletes use synthetic EPO or blood doping, like injecting stored RBCs to increase RBC levels and enhance performance artificially. Chronic overproduction of EPO, however, increases RBC levels, increasing blood viscosity and straining the cardiovascular system, subsequently increasing the risk of thrombosis.

Symptoms of Erythrocytosis

Erythrocytosis can manifest through various symptoms that could significantly impact your daily life. Recognizing these signs and seeking prompt medical advice are crucial steps in managing the condition effectively.

Headaches

Headaches are a common symptom of erythrocytosis and can vary in severity. These headaches primarily result from increased blood viscosity, which can impair the flow of oxygen-rich blood to the brain, causing discomfort and pain.

As RBCs increase, the blood becomes thicker and more viscous. This change can slow down blood circulation and diminish the efficiency of oxygen delivery to various bodily tissues, including the brain. The resulting shortage of oxygen can then trigger headaches, among other symptoms.

Itching

Itching is a significant symptom of erythrocytosis. As the number of RBCs increases, blood flow through small capillaries in the skin can increase. This enhanced blood flow can cause sensations of warmth and itching, which may be particularly uncomfortable and persistent.

Increased turnover of RBCs can lead to a higher count of mast cells, which release histamine, a compound commonly associated with allergic reactions and itchiness. This symptom intensifies when the skin gets warmer and blood flow to the skin’s surface increases.

Reddening of the Face

Reddening of the face, or facial plethora, is due to the increased concentration of RBCs. This elevation in RBCs raises blood volume and flow, particularly in capillary-rich areas such as the face, giving it a flushed or ruddy appearance.

The primary feature of erythrocytosis is the higher number of circulating RBCs, increasing blood volume and pressure. This condition leads to more blood flowing through the facial capillaries, causing the skin to appear more reddened in local areas.

Dizziness or Vertigo

Dizziness and vertigo can manifest in individuals with this condition, primarily due to the high RBC count associated with this condition. These symptoms stem from increased blood viscosity, which affects blood flow dynamics, particularly to the brain, impacting its function.

Increased RBC counts can thicken the blood, hindering its smooth flow through small vessels and reducing cerebral blood flow. Despite the higher number of RBCs, the slowed flow can decrease brain oxygenation, causing symptoms like dizziness or episodes of vertigo.

Fatigue or Weakness

Fatigue or weakness occurs despite increased RBCs because it does not guarantee effective oxygen delivery to organs and tissues. This paradoxical oxygen shortage can diminish energy levels and impact overall well-being, leading individuals to feel persistently tired or weak.

Thicker, more viscous blood from a high RBC counts can restrict circulation in small capillaries, impairing oxygen and nutrient delivery to tissues like muscles and the brain. This influences strength and energy levels, impacting the quality of daily life.

Vision Issues

Blurred vision in erythrocytosis can occur due to increased blood viscosity, which impairs microcirculation. This includes the delicate blood vessels in the eyes, leading to potential visual disturbances as blood flow becomes restricted.

Elevated red blood cell counts thicken the blood and slow its flow, particularly through the small vessels in the eyes and can impair retinal function and cause blurred vision. This may progress to hyperviscosity syndrome in severe cases, leading to visual disturbances such as floaters and temporary vision loss.

Abdominal Discomfort and Fullness

An enlarged spleen is a common symptom in cases of erythrocytosis. This condition, also known as splenomegaly, may cause discomfort or pain in the left upper abdomen and a feeling of fullness without eating.

The spleen may become enlarged as it works harder to filter the excess RBCs associated with erythrocytosis. An enlarged spleen is more susceptible to injury and rupture, which can cause severe internal bleeding.

Shortness of Breath

In erythrocytosis, shortness of breath or dyspnea may appear paradoxical considering the increased mass of oxygen-carrying RBCs. However, the elevated blood viscosity and its impact on oxygen transport can significantly affect respiratory function, leading to noticeable breathing difficulties.

Elevated RBC counts thicken the blood, increasing viscosity and straining the heart’s pumping efficiency. This can diminish cardiac output and impair oxygen delivery to vital tissues like the lungs, causing tissue-level oxygen shortage and shortness of breath.

High Blood Pressure

Hypertension can be attributed to increased blood viscosity and volume associated with elevated RBC counts. This higher viscosity results in thicker blood, challenging the heart’s ability to pump efficiently and leading to elevated arterial pressure.

Increased RBC counts thicken the blood, requiring the heart to work harder to circulate it. This increased workload can lead to hypertension, which places additional stress on the cardiovascular system and heightens the risk of heart-related complications.

Confirming Erythrocytosis

Erythrocytosis is diagnosed through a series of tests that evaluate blood count, blood composition, and, in certain instances, bone marrow. These tests help assess the severity of the condition, pinpoint potential causes, and guide treatment plans.

Physical Exam and Clinical Review

Part of the standard procedure, a thorough physical exam assesses the appearance, such as skin color and cyanosis, and vital signs, including blood pressure, heart rate, peripheral pulses, breath sounds, and oxygen saturation, for a general impression of the condition. Providers also palpate the abdomen for masses in the abdomen.

A clinical review includes a family history of polycythemia, erythrocytosis, or blood disorders and a past medical history of pulmonary or heart disease. Medication prescriptions and intake, smoking habits, and recent high-altitude travel are noted, aiding in accurate diagnosis.

Complete Blood Count (CBC)

A CBC is typically the initial diagnostic test conducted when erythrocytosis is suspected. This comprehensive test evaluates various blood components, including counting RBCs, white blood cells, and platelets, providing crucial data about the patient’s hematologic health.

Particular attention is focused on the RBC count in cases of erythrocytosis. An elevated RBC count is a primary indicator of erythrocytosis and signals the need for further diagnostic efforts to understand the underlying causes and determine appropriate management strategies.

Erythropoietin (EPO) Levels

EPO is a hormone the kidneys produce that regulates RBC production. Measuring EPO levels in the blood is essential for diagnosing the specific type of erythrocytosis and understanding its cause.

EPO testing helps differentiate between primary and secondary erythrocytosis. Low or normal EPO levels suggest primary erythrocytosis, possibly due to a bone marrow disorder, whereas high levels may indicate secondary erythrocytosis triggered by chronic hypoxia or another underlying condition.

Hemoglobin and Hematocrit Levels

Hemoglobin is the protein in RBCs responsible for carrying oxygen, whereas hematocrit measures the proportion of blood composed of RBCs. Both are essential markers in evaluating blood health.

Testing hemoglobin and hematocrit levels is critical in diagnosing the condition. Elevated levels of these indicators directly point to erythrocytosis, suggesting that the blood may be thicker than normal and potentially prone to complications such as clotting and reduced circulation.

Blood Oxygen Level

Measuring blood oxygen levels can indicate whether erythrocytosis is a compensatory response to low oxygen levels or hypoxia in the body. This determination is crucial for understanding the underlying causes of increased RBC production.

When the body experiences low oxygen availability, it usually responds by producing more RBCs in combination with other physiologic functions, leading to secondary erythrocytosis. Blood oxygen levels are typically assessed using a pulse oximeter or through arterial blood gas analysis, which is essential for diagnosing and guiding treatment.

Genetic Tests

Genetic tests are valuable for detecting mutations that might lead to primary erythrocytosis. These tests identify gene changes that impact the production of RBCs or the regulation of EPO.

It confirms a diagnosis of primary erythrocytosis by pinpointing specific genetic mutations. This helps distinguish it from secondary causes, ensuring that the management and treatment strategies are appropriately tailored to the underlying cause of the increased RBC count.

Bone Marrow Sampling

A bone marrow biopsy involves extracting a small sample of bone marrow tissue for examination. This diagnostic procedure is crucial when a primary bone marrow disorder like polycythemia vera is suspected, as it allows for direct analysis of marrow function.

Analyzing bone marrow helps identify abnormalities in blood cell production and can provide conclusive evidence of disorders impacting the marrow. This step is essential for confirming the nature of erythrocytosis and guiding appropriate treatment strategies.

Treatments for Erythrocytosis

Managing erythrocytosis effectively is crucial to preventing complications and improving quality of life. Treatment strategies are customized to address the root cause of your condition and may include a combination of medications, procedures, and lifestyle adjustments.

Medication

Medications are a non-invasive, convenient way of managing this condition, particularly in cases like polycythemia vera. Treatment often includes medications controlling RBC production, antimetabolites reducing RBC mass, as well as nonsteroidal anti-inflammatory drugs (NSAIDs) and blood thinners that reduce clotting.

The primary goal is to alleviate symptoms and minimize the risk for thrombosis. Medication adjustments are also considered during the management plan, especially with androgens, erythropoiesis-stimulating agents (ESAs), diuretics, anabolic steroids, and testosterone, as these can induce erythrocytosis or be part of the treatment regimen.

Patients on androgens or ESAs require regular laboratory checks to control RBC mass, with potential dosage adjustments. Those on diuretics need consistent fluid and electrolyte assessments. Patients on testosterone or anabolic steroids with erythrocytosis may need dosage reductions or alternative therapies.

Oxygen Therapy

Oxygen therapy may be advised if erythrocytosis is caused by chronic low oxygen levels or hypoxia. By increasing the amount of oxygen the body receives, this treatment can signal the body to reduce RBC production, addressing the condition’s root cause.

This therapy is especially beneficial for individuals with conditions like chronic obstructive pulmonary disease (COPD), which often leads to secondary erythrocytosis. By improving oxygen delivery, the therapy helps stabilize RBC levels and alleviate symptoms associated with oxygen deprivation.

Fluid Management

Adequate hydration is essential for managing erythrocytosis, where increased RBC counts lead to thicker blood. Staying well-hydrated helps to dilute the blood concentration, promoting smoother flow and reducing risks associated with high blood viscosity, like blood clots and vascular complications.

Increasing water intake boosts blood plasma volume, effectively thinning the blood and lowering its viscosity. This improved blood flow reduces heart strain and decreases clot risks, making regular hydration essential for preventing complications of erythrocytosis.

For electrolyte concerns, consuming enhanced water or oral rehydration solutions helps maintain electrolyte levels. Although less common in routine management, intravenous hydration may be employed in clinical settings to achieve rapid hydration when oral intake is inadequate or unsuitable.

Blood Volume Reduction

Therapeutic phlebotomy is a treatment that involves removing blood from your body to reduce the volume of RBCs and decrease blood viscosity. This procedure can alleviate symptoms and reduce the risk of complications such as blood clots.

Regular phlebotomy sessions may be necessary for those with significantly elevated hematocrit levels to maintain optimal RBC counts. This ongoing treatment helps prevent the potentially severe complications associated with high blood viscosity, ensuring better overall health and quality of life.

Treatment of Underlying Conditions

Effectively treating conditions like sleep apnea, a common cause of low oxygen levels and subsequent erythrocytosis, with continuous positive airway pressure (CPAP) therapy can significantly improve the condition by normalizing oxygen levels during sleep.

When erythrocytosis stems from a kidney tumor that boosts EPO production, surgical removal typically resolves the condition. Accurate diagnosis and tailored treatment plans are crucial, as each cause of erythrocytosis requires specific interventions.

Lifestyle Changes

Lifestyle changes can address the causes of secondary erythrocytosis. Quitting smoking, maintaining a healthy weight, staying hydrated, and regular physical activity are important adjustments that can significantly enhance blood oxygen levels and overall health, potentially easing the severity of erythrocytosis.

Lifestyle changes can be especially beneficial for individuals with erythrocytosis linked to modifiable lifestyle factors or experiencing mild secondary erythrocytosis without severe conditions. These adjustments can manage symptoms, slow progression, enhance quality of life, and reduce dependence on invasive treatments.

Frequently Asked Questions

What is erythrocytosis, and what are its types?

Erythrocytosis is characterized by an abnormally high number of RBCs in the bloodstream, which increases blood viscosity and can lead to various health complications. It is typically divided into two main types: primary and secondary erythrocytosis.

Primary erythrocytosis, a rare condition, stems from a genetic mutation causing excessive RBC production in the bone marrow. Secondary erythrocytosis is triggered by external factors, like chronic low oxygen levels and the environment, which lead to increased RBC production as a compensatory response.

What are some of the main causes of erythrocytosis?

Erythrocytosis occurs for various reasons, encompassing genetic factors, lifestyle influences, and medical conditions. Primary erythrocytosis often results from genetic mutations that cause the bone marrow to produce excessive RBCs. This type is usually inherent and not influenced by external conditions.

Secondary erythrocytosis arises from conditions that induce prolonged low oxygen levels due to factors like high-altitude living or chronic heart and lung diseases. Other contributors include smoking, intense athletic training, specific medications that increase RBC production, and tumors secreting EPO.

What are the symptoms of erythrocytosis?

Erythrocytosis can manifest through various symptoms, including headaches, itching, facial redness, dizziness, fatigue, vision problems, shortness of breath, and high blood pressure, which are diverse due to the broad impact of high RBC counts.

Erythrocytosis, marked by a high RBC count, can impair oxygen supply and blood circulation, leading to symptoms and severe complications. This emphasizes the importance of monitoring and managing the condition.

How is erythrocytosis treated?

Managing erythrocytosis involves addressing its root causes and symptoms. Strategies include medications that decrease blood clotting and lower RBC mass and adjustments or discontinuations that increase RBC production. Oxygen therapy is essential for low-oxygen-induced erythrocytosis.

Maintaining hydration to dilute blood for smoother flow and reduced viscosity is essential to prevent blood clotting. Therapeutic phlebotomy reduces RBC volume and alleviates symptoms. Additionally, addressing underlying conditions and promoting lifestyle changes, like quitting smoking or maintaining a healthy weight, are also important treatment strategies.