Polycythaemia is a blood disorder characterized by an abnormally high number of red blood cells circulating in the bloodstream. This condition can affect overall health by altering the consistency of blood.
Understanding Polycythaemia
Polycythaemia involves an increase in the red blood cell count, hemoglobin levels, or hematocrit, which is the percentage of red blood cells in the total blood volume. When there are too many red blood cells, the blood becomes thicker and more viscous. This increased thickness can impede normal blood flow throughout the body. Red blood cells are responsible for transporting oxygen from the lungs to various tissues and organs. An excessive number of these cells can paradoxically hinder oxygen delivery due to the sluggish circulation.
Unpacking the Causes
The causes of polycythaemia are broadly categorized into primary and secondary types. Primary polycythaemia, known as Polycythemia Vera (PV), is a rare, acquired disorder originating in the bone marrow. In PV, the bone marrow produces too many red blood cells, and sometimes also an excess of white blood cells and platelets. This overproduction is linked to a genetic mutation, specifically in the JAK2 gene, found in about 90% to 95% of PV cases. This mutation leads to uncontrolled cell growth in the bone marrow.
Secondary polycythaemia, a more common form, develops as a response to an underlying condition that stimulates the body to produce more red blood cells. This often occurs due to chronic low oxygen levels, which prompts the kidneys to release erythropoietin (EPO), a hormone that signals the bone marrow to produce red blood cells. Conditions such as chronic lung disease, sleep apnea, or living at high altitudes can lead to this chronic low oxygen state. Other causes include certain kidney diseases, tumors that secrete EPO, and the use of substances like testosterone or anabolic steroids. Unlike primary polycythaemia, secondary polycythaemia is typically a physiological response to a specific stimulus rather than an intrinsic bone marrow defect.
Recognizing the Signs
The symptoms associated with polycythaemia can vary widely among individuals and often develop gradually over time. Common indicators include headaches, dizziness, and persistent fatigue. Some individuals may experience shortness of breath or blurred vision as the condition progresses.
A distinctive symptom is itching, which is often intensified after a warm bath or shower. Other signs can include redness or burning sensations in the hands and feet, a condition known as erythromelalgia. An enlarged spleen, felt as a feeling of fullness or discomfort in the upper left abdomen, may also be present. Less common symptoms might involve nosebleeds or bleeding gums. It is important to note that these symptoms are not exclusive to polycythaemia and a medical evaluation is necessary for an accurate diagnosis.
Diagnosis and Management Approaches
Diagnosing polycythaemia typically begins with a complete blood count (CBC), which can reveal high levels of hemoglobin, hematocrit, and an elevated red blood cell count. If Polycythemia Vera (PV) is suspected, further tests may include a bone marrow biopsy to examine the bone marrow’s cellularity and a genetic test to detect the JAK2 gene mutation, which is present in most PV cases. Additionally, measuring erythropoietin (EPO) levels can help differentiate between primary and secondary forms, as EPO levels are typically low in PV and normal or high in secondary polycythaemia.
Management approaches differ depending on the type of polycythaemia. For primary polycythaemia (PV), a primary treatment is phlebotomy, which involves regularly removing a small amount of blood to reduce the red blood cell count and blood thickness. Low-dose aspirin is often prescribed to help prevent blood clots. When phlebotomy alone is insufficient or for higher-risk patients, medications such as hydroxyurea, interferon-alpha, or ruxolitinib may be used to control blood cell production.
In cases of secondary polycythaemia, the main goal is to address the underlying cause. For instance, if chronic low oxygen is due to sleep apnea, treating the sleep apnea can help normalize red blood cell production. Lifestyle adjustments, such as maintaining good hydration, are also encouraged for both types to help manage blood viscosity. Regular monitoring and tailored treatment plans are essential to manage the condition effectively.
Potential Health Implications
If left unmanaged, polycythaemia can lead to several serious health complications, primarily due to the increased thickness of the blood. One of the most significant risks is the formation of blood clots, known as thrombosis. These clots can occur in various parts of the body, potentially leading to a heart attack, stroke, or deep vein thrombosis (DVT) in the legs, which can then travel to the lungs, causing a pulmonary embolism. The sluggish blood flow also increases the risk of bleeding or bruising, despite the higher cell counts.
Another common implication is an enlarged spleen, or splenomegaly, as the spleen works harder to filter the increased volume of blood cells. Over time, the sustained overproduction of blood cells can stress the bone marrow. In rare instances, particularly with Polycythemia Vera, the condition may progress to myelofibrosis, a disorder where scar tissue replaces bone marrow, or, very rarely, to acute myeloid leukemia, a more aggressive form of blood cancer. Ongoing medical care is important to monitor the condition and implement strategies to prevent these potential health implications.